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SPO2(AFE4403)

ECG(ADS1292R)

5V0 Input Voltage

Robert Tolbert

Rechargeable battery

Battery Charger + Monitor

(BQ24232)

3V7@65mA

DC/DC Boost(TPS61099)

5V2 LDOTPS769

5V0

DC/DC Buck(TLV62569)

3V3

LDOTLV755

3V0

3V3

3V3

LED dRV/TX CTRL

5V0@10mA

RX DIG/ANA

[email protected]@75uA

DVDD AVDD

3V0@250uA

Battery Voltage:Nominal: 3.6V

Charging Voltage: 4.2VDischarging Voltage: 2.8V

2 Electrode + RLD ECG

LED TX

PD RX

TIDA-01614

SCLK

DinDout

SPI CLK

SPI Master InSPI Master Out

PWDN RESET

CS SPI TE

RESET

Pace Detection Module

I2C_SCL

TMP117

I2C_SDA

Dout Din SCLK

3V3 @ 5mA

3V3 @ 135uA

Temperature Sensor Module

Pace detect

CS2CS

CRG

3V3

Vbatt

PGAP PGANI2C_SCLI2C_SDA

ECG Analog Output

3V3 @10mA

LEDs:Battery charging indication

Low battery indication

MSP432P401

AVDDSCS

SPI TE

RESET

Defib Sense

Alarm

Low Battery Indication

SCK

DIN

DOUT

I2C_SCL

I2C_SDA

ISOW7842 TRS3232

Tx1

Rx1

DIO

DIO

DIO

DIO

Pace detect

DIO

DIO

DIO

DIO

DIO

SIMO

DIO

DIO

SOMI

Isolated UART

Vsi

3.3V@56mA

Vso

3.3V@8mA

32MHz

Vbatt AIO

UARTTx1

Rx1

ECG Analog output AIO

MCLK8MHz

8MHz

8MHz2MHz

2MHz

HFXIN

HFXOUT

Tx2

Rx2

SOMI

SIMO

CD74HC4040

3V3@80uA

CPQ2

TMP117

3V3 @ 135uA


I2C_SCLI2C_SDA

TMP117

3V3 @ 135uA


I2C_SCLI2C_SDA

3V3

1TIDUEO2A–March 2019–Revised May 2019Submit Documentation Feedback

Copyright © 2019, Texas Instruments Incorporated

Multiparameter Front-End Reference Design for Vital Signs Patient Monitor

Design Guide: TIDA-01614Multiparameter Front-End Reference Design for VitalSigns Patient Monitor

DescriptionThis reference design is for a multiparameter front-endof a patient monitor that measures vital signparameters like electrocardiogram (ECG), heart rate,SpO2, and respiration. It uses biosensing front-endintegrated circuits, like the AFE4403 and ADS1292Rdevices, to measure these parameters. It also usesthree TMP117 sensors to accurately measure skintemperature. The design can interface with the pacedetection module to detect the pace pulse. The designalso uses an isolated UART connection to transferdata to a computer. The entire front-end subsystemruns on a rechargeable 3.7-V Lithium-ion (Li-ion)battery.

Resources

TIDA-01614 Design FolderAFE4403 Product FolderBQ24232 Product FolderMSP432P4011 Product FolderADS1292R Product FolderTMP117 Product FolderTIDA-010005 Design Folder

ASK Our E2E™ Experts

Features• Monitors ECG, heart Rate, SpO2 %, respiration

rate, and skin temperature• Uses bio-sensing front-end AFE4403 for SPO2 and

heart rate measurement and ADS1292R for ECGand respiration measurement– Supports up to three LEDs and three photo-

diodes with ambient subtraction to improvesignal-to-noise Ratio (SNR) for SPO2 and heartmeasurement

– Single lead ECG Measurement with RLD• Supports three 0.1 Celsius accurate sensors to

measure the skin temperature• Interfaces to the pace detection module (Software-

configurable cardiac pacemaker detection modulereference design) to enable pacemaker detection

• Enables data transfer over isolated UART interface• Runs on a one cell Li-ion rechargeable battery

Applications• Medical sensor patches• Multiparameter patient monitor• Pulse oximeter• Electrocardiogram (ECG)

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An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and otherimportant disclaimers and information.

http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=TIDUEO2A

http://www.ti.com/product/TIDA-01614

http://www.ti.com/product/AFE4403?keyMatch=AFE4403

http://www.ti.com/product/BQ24232

http://www.ti.com/product/MSP432P4011

http://www.ti.com/product/ADS1292R

http://www.ti.com/product/TMP117

http://www.ti.com/tool/TIDA-010005

http://e2e.ti.com

http://e2e.ti.com/support/applications/ti_designs/

http://www.ti.com/solution/medical_sensor_patches

http://www.ti.com/solution/medical_diagnostic_patient_monitoring_therapy

http://www.ti.com/solution/pulse-oximetry-diagram

http://www.ti.com/solution/ecg_electrocardiogram

System Description www.ti.com

2 TIDUEO2A–March 2019–Revised May 2019Submit Documentation Feedback



1 System Description

1.1 Introduction to Patient Monitoring SystemVital signs measure the basic body functions which help assess the general physical health of a personand give clues to identify possible disorder.

In this reference design, five primary vital signs are monitored:• ECG• Heart Rate• SPO2• Respiration rate• Skin temperature

Using this reference design, the data is transferred using an isolated UART connection to a PC or host.

1.2 Parameters Measured Using TIDA-01614In this reference design, five primary vital signs are measured.

ECG detects cardiac (heart) abnormalities by measuring the electrical activity generated by the heart as itcontracts. ECG measurement uses ECG electrodes that are placed on the chest or at the four extremities(RA = right arm, LA = left arm, RL = right leg, LL = left leg). This reference design measures ECG with athree electrode operation, including the right leg drive, which improves CMRR. ECG is measured usingTI’s bio-sensing front-end IC ADS1292R.

The ADS1292R is a low-power, multichannel, simultaneously-sampling, 24-bit deltasigma (ΔΣ), analog-to-digital converter (ADC) with integrated programmable gain amplifiers (PGAs), internal reference, and anonboard oscillator. This device integrates various ECG-specific functions that support scalable ECG,sports, and fitness applications. The devices is used in high-performance, multichannel data acquisitionsystems by powering down the ECG-specific circuitry. The ADS1292R has a highly programmablemultiplexer that measures temperature, supply, input short, and RLD. Additionally, the multiplexer lets youprogram any of the input electrodes as the patient reference drive. You can choose the PGA gain fromone of seven settings (1, 2, 3, 4, 6, 8, and 12). The ADCs in the device offer data rates from 125 SPS to 8kSPS. Communication to the device is accomplished through an SPI-compatible interface. The deviceprovides two general-purpose I/O (GPIO) pins for general use. Multiple devices synchronize using theSTART pin. The internal reference is programmed to either 2.42 V or 4.033 V. The internal oscillatorgenerates a 512-kHz clock. The versatile right leg drive (RLD) block lets you choose the average of anycombination of electrodes to generate the patient drive signal.

Lead-off detection is accomplished either by an external pullup or pulldown resistor or the internal currentsource or sink from the device. An internal AC lead-off detection feature is available. The ADS1292Rversion also includes a fully-integrated respiration impedance measurement function. See the Low-power,2-channel, 24-bit analog front-end for biopotential measurements data sheet for further details.

The ECG subcircuit is implemented with the ADS1292R IC. The ADS1292R is clocked either by aninternal oscillator that generates a 512-kHz clock, or externally through the CLK pin (pin 17). Eachclocking method has its advantages and disadvantages. Although the external clock provides highaccuracy, it requires additional external components. However, the internal clock requires fewercomponents, but it suffers from temperature-dependent performance. As mentioned in the data sheet,internal clocking is ideal for low-power, battery-operated systems. The internal oscillator is trimmed foraccuracy at room temperature. The accuracy varies over the specified temperature range. The onlypermissible external clock frequencies are 512 kHz or 2.048 MHz. The higher frequency option helps theSPI run at a higher speed. The ADS1292R uses the SPI communication interface to communicate with aMicrocontroller (MCU), MPU, or DSP.

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http://www.ti.com/lit/pdf/SBAS502


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1.3 SPO2 MonitoringOxygen binds to hemoglobin in red blood cells as it moves through the lungs. It travels throughout thebody as arterial blood. A pulse oximeter uses two light frequencies (red and infrared) to determine whatpercentage of hemoglobin is saturated with oxygen. The percentage is called blood oxygen saturation, orSpO2. It is the percentage of oxygenated hemoglobin (hemoglobin containing oxygen) compared to thetotal amount of hemoglobin in the blood (oxygenated and non-oxygenated hemoglobin). A pulse oximeteralso measures and displays the pulse rate and the SpO2 level simultaneously. The signal obtained fromthe pulse oximeter is the photoplethysmographic (PPG) signal, which shows the blood flow at theextremities. SpO2 is measured by a pulse oximeter, which is an indirect, non-invasive method. It emitsand absorbs a light wave passing through blood vessels (or capillaries) in the fingertip. A variation of thelight wave passing through the finger gives the SpO2 measurement since the degree of oxygen saturationcauses variations in the blood’s color. This value is represented by a percentage. If your pulse oximetersays 98%, then each red blood cell is made up of 98% oxygenated hemoglobin and 2% non-oxygenatedhemoglobin. Normal SpO2 values vary between 95% and 100%. Anything lower than 90% may be acause for concern.

Red and infrared (IR) lights are used to estimate the true hemoglobin oxygen saturation of arterial blood.Oxyhemoglobin (HbO2) absorbs visible and infrared IR light differently than deoxyhemoglobin (Hb), andappears bright red as opposed to the darker brown of Hb. Absorption in the arterial blood is representedby an AC signal that is superimposed on a DC signal, representing absorptions in other substances likepigmentation in tissue, venous, capillary, bone, and so forth. The cardiac-synchronized AC signal isapproximately 1% of the DC level. This value is known as the perfusion index percentage.

Equation 1 shows how to approximate the ratio of ratios and R:R = (ACrms of Red) / (DC of Red) / (ACrms of IR) / (DC of IR) (1)

Equation 2 shows the standard model for computing SpO2:% SpO2 = 110 – (25 × R) (2)

This model is often used in medical devices literature. However, accurate % SpO2 is computed based onthe empirical calibration of the ratio of ratios for the specific device.

1.4 Pace DetectionThe TIDA-01614 can be interfaced to TI's pace detection module (TIDA-010005) to identify a pacemakerpulse in the ECG waveform. It detects the pace with rise time of (30 µs–200 µs), amplitude of (8 mV–700mV), and duration of (100 µs–2000 µs).

2 Key System SpecificationsTable 1 lists the different characteristics and specifications of the TIDA-01614 board.

Table 1. Key System Specifications

CHARACTERISTICS SPECIFICATIONS

ECG One lead ECG operation with RLD. Sampling rate of 500 samples per second,supports ECG sensitivity of 100 µV

SPO2 Measurement Works in transmissive SPO2, refresh rate of 500 HzSkin Temperature Measurement Three temperature sensor with 0.1 degree accuracy

Pace pulse Rise-time (TR) measurementrange 30–200 µs

Pace pulse duration (TD) measurementrange 0.1–2 ms

Input Pace signal amplitude range 8 mV–700 mVInput Voltage (Vin) 5 V from Micro-USB

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Patient Monitor

Battery Charger USB Input

Skin TemperatureSensor

PC

ECG ElectrodeSPO2 (Finger Clip)

Isolated UART

ECG

System Overview www.ti.com




3 System Overview

3.1 High-Level System DescriptionTypically patient monitors are connected to the body so they can measure multiple parameters of thebody. Figure 1 shows a high-level block diagram of such a system. The system connects to the PCthrough a wired, isolated UART connection.

Figure 1. System Level Block Diagram

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SPO2(AFE4403)

ECG(ADS1292R)

5V0 Input Voltage

Robert Tolbert

Rechargeable battery

Battery Charger + Monitor

(BQ24232)

3V7@65mA

DC/DC Boost(TPS61099)

5V2 LDOTPS769

5V0

DC/DC Buck(TLV62569)

3V3

LDOTLV755

3V0

3V3

3V3

LED dRV/TX CTRL

5V0@10mA

RX DIG/ANA

[email protected]@75uA

DVDD AVDD

3V0@250uA

Battery Voltage:Nominal: 3.6V

Charging Voltage: 4.2VDischarging Voltage: 2.8V

2 Electrode + RLD ECG

LED TX

PD RX

TIDA-01614

SCLK

DinDout

SPI CLK

SPI Master InSPI Master Out

PWDN RESET

CS SPI TE

RESET

Pace Detection Module

I2C_SCL

TMP117

I2C_SDA

Dout Din SCLK

3V3 @ 5mA

3V3 @ 135uA


Pace detect

CS2CS

CRG

3V3

Vbatt

PGAP PGANI2C_SCLI2C_SDA

ECG Analog Output

3V3 @10mA

LEDs:Battery charging indication

Low battery indication

MSP432P401

AVDDSCS

SPI TE

RESET

Defib Sense

Alarm

Low Battery Indication

SCK

DIN

DOUT

I2C_SCL

I2C_SDA

ISOW7842 TRS3232

Tx1

Rx1

DIO

DIO

DIO

DIO

Pace detect

DIO

DIO

DIO

DIO

DIO

SIMO

DIO

DIO

SOMI

Isolated UART

Vsi

3.3V@56mA

Vso

3.3V@8mA

32MHz

Vbatt AIO

UARTTx1

Rx1

ECG Analog output AIO

MCLK8MHz

8MHz

8MHz2MHz

2MHz

HFXIN

HFXOUT

Tx2

Rx2

SOMI

SIMO

CD74HC4040

3V3@80uA

CPQ2

TMP117

3V3 @ 135uA


I2C_SCLI2C_SDA

TMP117

3V3 @ 135uA


I2C_SCLI2C_SDA

3V3

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3.2 Block DiagramFigure 2 shows the TIDA-01614 block diagram.

Figure 2. TIDA-01614 Block Diagram

This design measures ECG, Respiration, SpO2, heart rate, and skin temperature. ECG and respiration aremeasured using the IC ADS1292R with standard wet ECG electrodes. The SpO2 and heart rate aremeasured using the IC AFE4403 and the standard transmissive type finger clip. Skin temperature ismeasured with TMP117 temperature sensors. The TIDA-010005 (Software-configurable cardiacpacemaker detection module reference design) is interfaced to this reference design to detect thepresence of pace pulse and to read the pace pulse parameters.

The whole system runs with a 3.7-V rechargeable Li-ion battery. This design uses a TPS61099 boostregulator to convert the battery from 3.7 V to 5.2 V. The LDO TPS76901 generates a 5-V output with aninput voltage of 5.2 V. 3.3 V is generated using the buck converter TLV62569 with an input voltage of 5.2V. A value of 3 V is generated using the LDO TLV75530 with an input voltage of 3.3 V. This referencedesign uses an isolated UART connection with the ISOW7821 digital isolator and TRS3232 transceiver.

3.3 Design ConsiderationsThis section provides the design details for the monitoring system.

3.3.1 ECG and Respiration CircuitFigure 3 shows the schematic of the ECG subcircuit and the nets of ADS1292_ERA, ADS1292_ELA, andADS1292_RLD and corresponds to the probes. The more channels an ECG monitoring system has, thebetter the ECG signal can be analyzed. ADS1292R is equipped with only two channels. Figure 4 showsthat Channel 1 is used for respiration rate calculation and Channel 2 is used for ECG measurement. Thefrequency from the ECG signals can range from 0.01–300 Hz. ECG drift occurs when the ECG signalsdrift all over the monitoring device. Current injection and resistor biasing reduce ECG drift, but for addedsecurity, the ECG subcircuit uses both methods. Figure 4 shows resistors R21, R22, R24, R10, andcapacitor C16, which form the RLD current injection method. Figure 3 shows resistors R15, R17, R54, andR72, which form the resistor biasing method. Figure 5 shows the ADS1292 decoupling capacitors.

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ADS1292_ERA

ADS1292_ELA

0.1µFC17 2200pFC18ADS1292_RESP_MODN/IN3N

470pF

C15

4.70k

R16

10.0MR17

10.0MR15

ADS_AVDD

AVSS

1

3

2

D15BAV99,215

ADS1292_IN1N

ADS_AVDD

AVSS

0.1µFC19 2200pFC20ADS1292_RESP_MODP/IN3P

470pF

C73

4.70k

R71

10.0MR72

10.0MR54

ADS_AVDD

AVSS

1

3

2

D17BAV99,215

ADS1292_IN1P

ADS_AVDD

47.0kR11

0.1µF

C10

0R13

1

3

2

D10BAV99,215

ADS1292_IN2N

ADS_AVDD

AVSS

47.0kR12

47.0kR74

0.1µF

C91

0R76

1

3

2

D19BAV99,215

ADS1292_IN2P

2.7V

D18MMSZ5223BS-7-F

ADS_AVDD

AVSS

47.0kR75

RLD1

RLD1

AVSS

AVSS

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U20TVS0500DRVR

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U17TVS0500DRVR

AVSS

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U21TVS0500DRVR

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U22TVS0500DRVR

AVSS

R14

OX202KE

R73

OX202KE

1

3

2

D8

BAV99,215

AVSS

ADS_AVDD

1

3

2

D9BAV99,215

AVSS

ADS_AVDD

47pFC84

ADS1292_IN1N

47pFC85

ADS1292_IN2N

47pFC88

AVSS

47pFC87

AVSS

47pFC82

AVSS

47pFC8

AVSS

1Y

2X





The ADS1292R is a two-channel device, but if respiration rate detection is enabled, then Channel 1 canno longer measure ECG signals. Four pins are needed to detect the respiration rate:• IN1P• IN1N• RESP_MODP• RESP_MODN

The ECG subcircuit can only measure ECG signals, but you can extract the ECG signal respiration ratewith mathematical manipulation.

Figure 3. ECG Subcircuit - Leads

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1µFC11

0.1µFC12

1µFC13

0.1µFC14

GND

ADS_DVDD

Place the decoupling capacitor close to the power pins in Layout.

120 ohm

L19

ADS_DVDD

120 ohm

L20

ADS_AVDD

ADS_AVDDVCC_3.3V

VCC_3.0V

AVSS

PGA1N1

PGA1P2

IN1N3

IN1P4

IN2N5

IN2P6

PGA2N7

PGA2P8

VREFP9

VREFN10

VCAP111

AVDD12

AVSS13

CLKSEL14

PWDN/RESET15

START16

DGND24

DVDD23

DRDY22

DOUT21

SCLK20

DIN19

CS18

CLK17

GPIO2/RCLK225

GPIO1/RCLK126

VCAP227

RLDINV28

RLDIN/RLDREF29

RLDOUT30

RESP_MODP/IN3P31

RESP_MODN/IN3N32

U15

ADS1292RIPBS

PGAP

PGAN

ADS1292_IN1P

ADS1292_RESP_MODP/IN3P

ADS1292_IN2P

ADS1292_IN2N

ADS1292_RESP_MODN/IN3N

ADS1292_IN1N

ADS_START

ADS_CLK_SEL

ADS_AVDDADS_DVDD

1µF

C24

1µF

C25

GND

AVSS

10µFC22

0.1µFC21

AVSS

VREFP

0R460R53

0R28

Dout

Din

SCLK

0R26ADS_CS

ADS_DRDY

100kR24

0R211.00MR22

1500pF

C16

RLD_OUTPUT

0R20RESET2

0R19

10kR18ADS_GPIO1

11

TP

3

11

TP

4

11

TP

5

11

TP

61

1T

P101

1T

P9

11

TP

8

11

TP

7

XIN_MSP

AVSS

0R78

0R79 2200pFC72

2200pFC23





Figure 4. ECG Subcircuits – ADS1292R and RLD

Figure 5. ECG Subcircuit – Decoupling Capacitor and Ferrite Bead

Figure 3 shows diodes D19, D15, D8, D17, D9, D10, and D11. These diodes limit the voltage that appearson the ADS1292R pins. Figure 3 shows optional TVS diodes U17, U20, U21, U22, U18, and U19. Thesediodes protect the circuitry against excess voltage.

The PGAP and PGAN pins extract pace pulse present in the ECG signal. These signals are given to theJ9 connector, which connect to the pace pulse detection module. See reference design TIDA-010005 forthe pacemaker detection circuit. You can conduct a test by connecting the TIDA-010005 board. SeeSection 4.2 for the test results.

Figure 6 shows a two electrode mode of operation where the ADS1292_ERA and ADS1292_ELAelectrodes are connected. To improve the CMRR in this mode, R7 is populated. The RLD_OUTPUT of theIC and the resistive divider form with R75 and R74 to generate equal and opposite voltage, cancelling outthe CM voltage at the pin ADS1292_IN2N. Similarly, R12 and R11 form a resistive divider and cancel outthe CM voltage at the input of the IC pin ADS1292_IN2P.

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D

ADS1292_ERA

ADS1292_ELA

0.1µFC17 2200pFC18ADS1292_RESP_MODN/IN3N

470pF

C15

4.70k

R16

10.0MR17

10.0MR15

ADS_AVDD

AVSS

1

3

2

D15BAV99,215

ADS1292_IN1N

ADS_AVDD

AVSS

0.1µFC19 2200pFC20ADS1292_RESP_MODP/IN3P

470pF

C73

4.70k

R71

10.0MR72

10.0MR54

ADS_AVDD

AVSS

1

3

2

D17BAV99,215

ADS1292_IN1P

ADS_AVDD

47.0kR11

0.1µF

C10

0R13

1

3

2

D10BAV99,215

ADS1292_IN2N

ADS_AVDD

AVSS

47.0kR12

47.0kR74

0.1µF

C91

0R76

1

3

2

D19BAV99,215

ADS1292_IN2P

2.7V

D18MMSZ5223BS-7-F

ADS_AVDD

AVSS

47.0kR75

RLD1

RLD1

ADS1292_RLD10.0k

R9

AVSS

1

3

2

D11BAV99,215

ADS_AVDD

AVSS

0R7

RLD

1

RLD_OUTPUT10.0k

R10

PGA1N1

PGA1P2

IN1N3

IN1P4

IN2N5

IN2P6

PGA2N7

PGA2P8

VREFP9

VREFN10

VCAP111

AVDD12

AVSS13

CLKSEL14

PWDN/RESET15

START16

DGND24

DVDD23

DRDY22

DOUT21

SCLK20

DIN19

CS18

CLK17

GPIO2/RCLK225

GPIO1/RCLK126

VCAP227

RLDINV28

RLDIN/RLDREF29

RLDOUT30

RESP_MODP/IN3P31

RESP_MODN/IN3N32

U15

ADS1292RIPBS

PGAP

PGAN

ADS1292_IN1P

ADS1292_RESP_MODP/IN3P

ADS1292_IN2P

ADS1292_IN2N

ADS1292_RESP_MODN/IN3N

ADS1292_IN1N

ADS_START

ADS_CLK_SEL

AVSS

ADS_AVDDADS_DVDD

1µFC11

0.1µFC12

1µFC13

0.1µFC14

GND

ADS_DVDD

Place the decoupling capacitor close to the power pins in Layout.

120 ohm

L19

ADS_DVDD

120 ohm

L20

ADS_AVDD

ADS_AVDD

1µF

C24

1µF

C25

GND

AVSS

10µFC22

0.1µFC21

AVSS

VREFP

0R460R53

0R28

Dout

Din

SCLK

0R26ADS_CS

ADS_DRDY

100kR24

0R211.00MR22

1500pF

C16

RLD_OUTPUT

0R20RESET2

0R19

10kR18ADS_GPIO1

1

2

3

4

5

6

7

8

9

11

10

J15

ADS1292_ERA

ADS1292_ELA

ADS1292_RLD

AVSS

0.01µFC9

VCC_3.3V

VCC_3.0V

11

TP

3

11

TP

4

11

TP

5

11

TP

61

1T

P101

1T

P9

11

TP

8

11

TP

7

XIN_MSP

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U20TVS0500DRVR

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U17TVS0500DRVR

AVSS

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U21TVS0500DRVR

IN4

IN5

GN

D1

GN

D2

IN6

GN

D3

PA

D7

U22TVS0500DRVR

AVSS

IN4

IN5

GND1

GND2

IN6

GND3

PAD7

U18

TVS0500DRVR

IN4

IN5

GND1

GND2

IN6

GND3

PAD7

U19

TVS0500DRVR

AVSS

R14

OX202KE

R73

OX202KE

R8

OX202KE

AVSS

AVSS

AVSS

AVSS

0

R68

GNDAVSS

0R78

0R79

1

3

2

D8

BAV99,215

AVSS

ADS_AVDD

1

3

2

D9BAV99,215

AVSSADS_AVDD

0

R77

47pFC84

ADS1292_IN1N

47pFC85

ADS1292_IN2N

47pFC88

AVSS

47pFC87

AVSS

47pFC82

AVSS

47pFC8

AVSS

1Y

2X

2

3

1

2

Q1BC847BW,115

3

1

2

Q2BC847BW,115

AVSS

AVSS

Y

1

3

1

2

Q3BC847BW,115

3

1

2

Q4BC847BW,115

AVSS

AVSS

X

AVSS

1µF

C86

ADS_AVDD

P4.5_A4

39k

R88

39k

R93

10.0k

R89

10.0k

R90

10.0k

R94

10.0k

R95

47

R91

470R27

470R92

2200pFC72

2200pFC23





Figure 6. ADS1292_ERA and ADS1292_ELA – Two-Electrode Operation

In the three electrode mode of operation, disconnect R7 and the RLD amplifier to create an equal andopposite signal, cancelling out the 50 or 60 HZ common mode signal coming from the body and improvingthe CMRR.

A 32-kHz or 64-kHz signal is sent through the R23 and R27 resistor to the right and left electrode. TheR23 and R27 resistors form a resistive divider and the body impedance of 500 Ω, which varies from 0.1 Ωto 1 Ω with respiration. The high-frequency envelope, modulated by the variation in the impedance of thebody, is fed differently through the R16 and R71 to the IC through ADS1292_IN1P and ADS1292_IN1N.Then, the envelope is demodulated and digitized to form the respiration. In this design, ADS1292R runswith an internal clock of 512 kHz.

For the ECG monitoring to be effective, the recorded ECG signals must be clean and free of noise. Anydistortion of the ECG signals from improper electrode-to-patient placement can lead to improper or misseddiagnosis. Use monitoring techniques to verify that electrodes are properly adhered to the patient. TheADS1292R offers lead-off detection, which is a built-in monitoring circuitry that constantly monitors theECG leads to ensure they are properly adhered to the patient’s skin. With the ADS1292R, lead-offdetection is implemented either by using an external pullup or pulldown resistor, or the device internalcurrent source or sink. An internal AC lead-off detection feature is also available. You do not need externalcircuitry to enable lead-off detection.

Figure 5 shows that decoupling capacitors C11, C12, C13, C14, and ferrite bead L19 and L20 havesufficient suppression to switch the noise from the 3.3 V switching power supply. Figure 10 shows that therespiration is switched off every 30 seconds, but the transistor switch keeps the pacemaker on.

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MSP432P401

Oscillator

UARTISOW7842 & TRS3232

Pace DetectionModule &TMP117

SPI

24 MHz

ADS1292R & AFE4403

AFE4403

I2C

2

3

1

2

Q1BC847BW,115

3

1

2

Q2BC847BW,115

AVSS

AVSS

Y

1

3

1

2

Q3BC847BW,115

3

1

2

Q4BC847BW,115

AVSS

AVSS

X

AVSS

1µF

C86

ADS_AVDD

P4.5_A4

39k

R88

39k

R93

10.0k

R89

10.0k

R90

10.0k

R94

10.0k

R95

47

R91

470R27

470R92





Figure 7. Electronic Switch

3.3.2 MSP432P401V

Figure 8. MCU Connections

This reference design uses the MSP432P401 microcontroller. Figure 8 shows SPI, UART, and I2Ccommunicating to the devices. ADS1292R and AFE4403 are interfaced by SPI. It is interfaced to PC usingthe UART interface. The pace detection module and temperature sensor communicates through the I2C.The microcontroller runs with the internal oscillator of 48 MHz. 24 MHz of the HSM clock is given from themicrocontroller to the AFE4403. Battery voltage is given to the IO pin of the microcontroller to indicate lowbattery voltage.

3.3.3 Timing DiagramFigure 9 shows ADS1292R and AFE4403 Read and UART transmission (AFE4403 RDY comes afterADS1292R read).

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ADS_RDY ADS1293Read

ReadAFE4403

2msec

UARTTransmission

AFE_RDY

2msec

Wait untilADS1292R readcompletes

ADS_RDY ADS1293Read

ReadAFE4403

2msec

UARTTransmission

AFE_RDY

2msec





Figure 9. Timing Diagram – Case 1

Figure 10 shows ADS1292R and AFE4403 Read and UART transmission (AFE4403 RDY comes whilereading ADS1292).

Figure 10. Timing Diagram – Case 2

Read the temperature sensor every two seconds. Respiration is switched off and pacemaker is ON every30 seconds.

3.3.4 SPO2 MeasurementIn this reference design, SPO2 is measured using the TI bio-sensing analog front-end IC AFE4403.Figure 11 shows different connections for the AFE4403 device. The AFE4403 devices needs followingpower supplies:• RX_ANA_SUP (3.3 V)• RX_DIG_SUP (3.3 V)• LED_DRV_SUP (5 V)• TX_CTRL_SUP (5 V)

RX_ANA_SUP (3.3 V) and RX_DIG_SUP (3.3 V) are generated using the U5 IC. The L9 and L10 ferritebeads are used to suppress the switching noise from 3.3 V switching power supply. LED_DRV_SUP (5 V)and TX_CTRL_SUP (5 V) are generated using the LDO U4.

For PPG measurement, the LEDS are driven using the TXP. The TXN is used for the red LED and the IRLED and TX_LED_3 (TX_LED_3 is not used in this design) is used for the green LED. The reflectedsignals are detected using PDs connected to the INP and INN. The BG pin is connected to the internalbandgap voltage and is decoupled using 2.2 µF.

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NC

A1

TX_CTRL_SUPA2

LED_DRV_GNDA3

TXNA4

TXPA5

LED_DRV_SUPA6

TX_REFB1

RX_DIG_GNDB2

TX3B3

DIAG_ENDB4

NC

B5

NC

B6

NC

C1

BGC2

AFE_PDNC3

SPISIMOC4

SPISOMIC5

SCLKC6

VCMD1

VSSD2

NC

D3

RESETD4

ADC_RDYD5

SPISTED6

INPE1

RX_ANA_GNDE2

NC

E3

RX_ANA_SUPE4

RX_DIG_SUPE5

CLKOUTE6

INNF1

RX_ANA_SUPF2

XINF3

XOUTF4

NC

F5

RX_DIG_GNDF6

U2AFE4403YZPR

2.2µFC28

2.2µFC27

GND

0.1µF

C30

VCC_3.3V

1µF

C31

GND

VCC_5.0V

0.1µF

C32

VCC_5.0V

GND

0.1µF

C29

VCC_3.3V

GND

0R

35

0R

36

22

R32TP14 MSP_CLK

AFE_CS

SCLK

Din

Dout

ADC_RDY

RESET1

10k

R29

AFE_PDNZ

DIAG_END

XINXOUT

TX30R33

0

R34

13

2

D3BAV99W-7-F GND

VCC_5.0V

TX_LED_3

0R38

0

R39

1

3

2

D4BAV99W-7-F GND

0R40

0

R41

1

3

2

D5BAV99W-7-F GND

TX_N

TX_P

TX_LED_N

TX_LED_P

TP15

TP16

1 234

L2

1.00kR30

0.01µF

C26

IN_NIN_PVCM_AFE

VCM_SHIELD

1

3

2

D2BAV99W-7-F

1

3

2

D1BAV99W-7-F

DET_N

DET_P

0R31

0R37

TP17

Jumper

Jumper

Jumper

Jumper

Jumper

Jumper

Jumper 1

2

3

Y1

CSTCE8M00G55-R0

GND

GND

GND

1

1D2

1CLK3

4

1Q5

1Q6

PRE

CLR

U11ASN74HC74QPWRQ1

10

2CLK11

2D12

13

2Q8

2Q9PRE

CLR

U11BSN74HC74QPWRQ1

VCC14

GND7

U11C

SN74HC74QPWRQ1

GNDGND

1µFC81

VCC_3.3V

22

R61

VCC_3.3V

ADC_RDY

ADS_GPIO1

ADS_START

100 ohmL1

0R1

TP2

TP12

1

2

3

4

5

6

7

8

9

11

10

J5

K202XHT-E9S-N

AVSS1 AVSS1

AVSS1

AVSS1

AVSS1

AVSS1

AVSS1

AVSS1

0

R67

GNDAVSS1

120 ohm

L10

120 ohmL9

RX_DIG_SUP

RX_DIG_SUP

RX_ANA_SUP

RX_ANA_SUP

GND

0

R70





Figure 11. AFE4403 Connection Schematic

Table 2 lists the connections between the AFE4403 and the MSP432P401V device.

Table 2. Connections Between the AFE4403 and MSP432P401V Device

AFE4403 PINNUMBER FUNCTION MSP432P401V

PIN NUMBER FUNCTION COMMENTS

F3 XIN 35 P4.4/HSMCLK/SVMHOUT/A9 AFE Clock

B4 DIAG_END 7 P1.6/UCB0SIMO/UCB0SDA Output signal that indicatescompletion of diagnostics

C3 AFE_PDN 20 P3.1/PM_UCA2CLK/ AFE-only power-down inputD4 RESET1 19 P3.0/PM_UCA2STE Reset for the AFED5 ADC_RDY 13 P2./PM_UCA1STE ADC Ready SignalC4 Dout 4 P1.3/UCA0TXD/UCA0SIMO SPI_OUTC5 Din 3 P1.2/UCA0RXD/UCA0SOMI SPI_INC6 SCLK 2 P1.1/UCA0CLK SPI ClockD6 AFE_CS 5 P1.4/UCB0STE AFE chip select

AFE4403 works with an external clock. 24 MHz HSMCLK from MSP432P401 is given to the AFE4404,which is internally divided by six to have 4 MHz for the AFE4403 ADC.

The SPO2 finger clip is connected to the J5 connector. The transmit section integrates the LED driver andthe LED current control section with an 8-bit resolution. The RED and IR LED reference currents can beindependently set. The driver works in H-Bridge configuration works in transmissive manner. The front-endreceiver consists of a differential current-to-voltage (I-V) transimpedance amplifier (TIA) that converts theinput photodiode current into an appropriate voltage. The feedback resistor of the amplifier isprogrammable to support a wide range of photodiode currents. Next to the TIA is an Amb cancellationDAC, Filtering stage, Buffer, and an ADC. See the AFE4403 ultra-small, integrated analog front-end forheart rate monitors and low-cost pulse oximeters data sheet for more details. The D1 to D5 diodes limitthe voltage that appear on the pins of the IC.

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VBUS

GND

Green

12

D6

TP21

GND

GND TS

VBUS1

D-2

D+3

ID4

GND5

678

11

10

9

J61051640001

GND

33.0R51

GND

60 ohmL5OUT

TP23

1

2

J7

B2B-PH-K-S(LF)(SN)

1 2

J1

10.0kR87

TS1

BAT2

BAT3

CE4

EN25

EN16

PGOOD7

VSS8

CHG9

OUT10

OUT11

ILIM12

IN13

TMR14

ITERM15

ISET16

EP17

U7

BQ24232RGTR

4.7µFC54

1µFC53

7.32kR50

3.09kR52

8.66kR99

56.2kR100

GND

TP18

1.05k

R55

Green

12

D13

1.05k

R49

1

2

J17





3.3.5 Li Ion Battery Charger

Figure 12. Li-Ion Battery Charger Using BQ24232

The following list provides details about the design:• Supply Voltage = 5 V• Charging current = 0.1 A• Input current limit, ILIM = 500 mA• Termination current = 25 mA• Safety timer duration, Fast charge = 7.5 hours• Battery temperature sense = 10 KΩ NTC (103AT-2)

How the fast charge current (ISET) is set:• RISET = [K(ISET) / ICHG]• K(SET) = 870 AΩ• RISET = R99 = [870 AΩ / 0.1 A] = 8.7 kΩ

How the input current limit (ILIM) is set:• RLIM = KILIM / I1-MAX• KILIM = 1530 AΩ• RILIM = 1530 AΩ / 0.5A = 3.06 kΩ

How the termination current threshold (ITERM, BQ24232) is set:• RITERM = RISET × ITERM × KITERM• KITERM = 0.03 A• RITERM = 8.7 kΩ × 0.025 A / 0.03 A = 7.25 kΩ

How the 7.5-hour fast-charge safety timer is set:• RTMR = tma × CHG• KTMR = 48 s / kΩ• RTMR = (7.5 hr × 3600 s/hr) / (10 × 48 s/kΩ) = 56.25 kΩ

If you are using a Li-ion battery, place a thermistor close to the battery and connect it to the Ts pin of thecharger for protection. If the temperature gets too high while it is charging, the thermistor turns off. In thisreference design, Connector J1 connects SEMITEC 103-AT-2 temperature sensor from the battery packto the Ts pin of the IC. See the USB-friendly lithium-ion batttery charger and power-path management ICdata sheet and bq24072/3/4/5/9(T) and bq24230/21.5-A single-chip li-ion and li-polymer chargemanagement IC EVM user's guide for detailed design instructions and recommendations. See TI'sWEBENCH® Design Center to generate a solution with this part.

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http://www.ti.com/lit/pdf/SLUS821

http://www.ti.com/lit/pdf/SLUS821

http://www.ti.com/lit/pdf/SLVU274

http://www.ti.com/lit/pdf/SLVU274

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1 2OUT REF

2

R RV V

R

u

IN1

OUT5

2

EN3

FB4

GND

U4

TPS76901DBVR

1µFC41

GND

VCC_5.2V

523kR43

169kR45

GND

VCC_5.0V

4.7uF

C35

GNDGND

TP25

GND

1µFC4

GND

VCC_3.0VVCC_3.3V

TP1OUT

5

GND2

NC4

EN3

IN1

U1

TLV75530PDBVR

10µFC47

10µFC2

10µFC3





This reference design uses a 3.7-V Li-Ion battery. The board consumes 120 mA, so the battery runscontinuously for 4.16 hours.

3.3.6 3-V Generation Using LDO

Figure 13. 3-V Generation Using TLV5530

Figure 13 shows the LDO circuit generating 3 V from a 3.3-V input with the TLV75530. This is a fixedoutput LDO. This reference design uses a 500-mAh 3.7-V Li-ion battery. The board consumes 120 mA, sothe battery runs for 4.16 hours continuously. This circuit provides 60 mAs of current. This 3 V providessupply to the ADS1292R ADS_AVDD supply. The TLV755P device is a 500-mA low-IQ small-size low-dropout regulator, with an input voltage range of 1.45 V to 5.5 V. The device is offered in fixed outputvoltages ranging from 0.6 V to 5 V. See the Low-voltage, low-noise power supply reference design forultrasound analog front end reference design and the TLV755P 500-mA, low IQ, small size, low dropoutregulator datasheet for detailed design instructions and recommendations. See TI's WEBENCH® DesignCenter to generate a solution with this part.

3.3.7 5-V Generation Using LDO

Figure 14. 5-V Generation Using TPS76901

Figure 14 shows the LDO circuit generating 5 V from a 5.2-V input using the TPS76901. The 5 V providesthe LED_DRV_SUP and TX_CTRL_SUP of the AFE4403 IC. The TPS76901 device is an ultra-low power100-mA low-dropout linear regulator.

Output Voltage SetFigure 14 shows the output voltage from the TPS76901 adjustable regulator being programmed with anexternal resistor. Equation 3 shows how to calculate the output voltage.

where• R1 = R43 and R2 = R45• VREF = 1.16 V typ (the internal reference voltage) (3)

Gives Vo = 5 V, with R43 = 523 kΩ, R45 = 169 kΩ and Vref = 1.16.

See the Ultra-low-power 100-mA low dropout linear regulator data sheet for detailed design instructionsand recommendations. See TI's WEBENCH® Design Center to generate a solution using this part.

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http://www.ti.com/lit/pdf/TIDUD73

http://www.ti.com/lit/pdf/TIDUD73

http://www.ti.com/lit/pdf/SBVS320

http://www.ti.com/lit/pdf/SBVS320



http://www.ti.com/lit/pdf/slvs959


1 1OUT FB

2 2

R RV V 1 0.6 V 1

R R

ª º ª º u u « » « »

« » « »¬ ¼ ¬ ¼

VINA1

SWB1

GNDA2

VOUTB2

FBC2

ENC1

U3

TPS61099YFFR

150µFC34

GND

10µFC36

2.2uHL3

1286AS-H-2R2M=P2

1.05MR42

249kR44

VCC_5.2V

GND GND

10pFC33

10µFC37

10µFC38

10µFC39

22µFC40

GND GND GNDGND

TP2410.0k

R23

10.0kR25

GND

OUT





3.3.8 5.2-V Generation Using DC/DC Converter

Figure 15. 5.2-V Generation Using DC/DC Converter

Figure 15 shows the switching circuit generating 5.2 V using the TPS61099 from the battery voltage,VBAT. Nominal value of VBAT is 3.7 V, but this varies between 2.8 V and 4.2 V. This 5.2-V boostconverter is used as input to the LDO TPS76901 to generate 5 V for the LED_DRV_SUP andTX_CTRL_SUP of the AFE4403 IC. This 5.2 V is the input to the TLV62569, a 3.3-V generating DC/DCconverter. This converter operates with a switching frequency of 400 kHz. See the TPS61099xsynchronous boost converter with ultra-low quiscent current data sheet for detailed design information.The TPS61099 device is a Synchronous Boost Converter with Ultra-Low Quiescent Current.

Output Voltage SetThe resistor divider network of R42 and R44 sets the output voltage. The reference voltage, VREF, is 1 V.Equation 4 helps you calculate the output voltage.

where• R1 = R42 and R2 = R44 and VREF = 1 V (4)

Substituting R42, R44, and VREF in Equation 4 gives you VOUT = 5.2 V.

See the TPS61099x synchronous boost converter with ultra-low quiscent current data sheet andTPS61099 evaluation module user's guide for detailed design instructions and recommendations. See TI'sWEBENCH® Design Center to generate a solution using this part.

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http://www.ti.com/lit/pdf/SLVSD88



http://www.ti.com/lit/pdf/SLVUAR2



1 1OUT FB

2 2

R RV V 1 0.6 V 1

R R

ª º ª º u u « » « »

« » « »¬ ¼ ¬ ¼

EN1

GND2

SW3

VIN4

FB5

U5

TLV62569DBVR

4.7µFC44

VCC_5.2V

GND

453kR47

97.6kR48

GND GND

22µFC49

GND

VCC_3.3V

4.7µFC43

GND

47µFC42

GND

0.068µF

C45

10µFC50

GND

10µFC51

GND

10µFC52

GND

2.2µH

L4

TP26





3.3.9 3.3-V Generation Using DC - DC Converter

Figure 16. 3.3-V Generation Using DC - DC Converter

Figure 16 shows the switching circuit generating 3.3 V using the TLV62569 from the 5.2-V DC/DCConverter. 3.3 V is provided to the following:• The MCU• The RX_DIG_SUP and RX_ANA_SUP supply of the AFE4403• The ADS DVDD of ADS1292R

This 3.3 V is the input to the 3 V-generating LDO TLV75530. Ferrite beads are used at each input to avoidswitching noise from the 3.3 V converter. This is designed to operate with a switching frequency of 400kHz. The TLV62569 2-A is a high efficiency synchronous buck converter in the SOT Package. See theTLV62569 2-A high efficiency synchronous buck converter in SOT package data sheet andTLV62568EVM-789 and TLV62569EVM-789 evaluation modules user's guide for detailed designinformation.

Output Voltage SetEquation 5 shows an external resistor divider setting the output voltage.

where• R1 = R47, R2 = R48 and VFB = 0.6 V (5)

Substituting R47, R48, and VFB in Equation 5 gives you Vout = 3.3 V.

See the Ultralow-power 100-mA low dropout linear regulator data sheet and TLV62568EVM-789 andTLV62569EVM-789 evaluation modules user's guide for detailed design information.

3.3.10 Isolated UARTThis reference design provides an isolated UART connection for the wired environment. The U8 ICISOW7821DWER is the isolator and U9, TRS3232DWR, is the UART transceiver. The J16 connectorconnects to the PC with an isolated UART if the voltage is 3.3 V. The J2 connector provides the UARTRX1 and TX1 without isolation. The J16 connector provides an isolated UART TX and RX.

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http://www.ti.com/lit/pdf/SLVSDG1

http://www.ti.com/lit/pdf/SLVUAY6

http://www.ti.com/lit/pdf/SLVSDG1



1

3

5 6

4

2

7

9 10

8

J9

PPTC052LFBN-RC

VCC_3.3V

I2C_SCL

I2C_SDA

Pace_Detect

GND

PGAP

PGAN

Analog_Output1

100 ohmL18

0R5

VCC_3.0V

0R6

Pace_Reset

10µFC92

GND

IO

10µFC59

1µFC61

0.1µFC63

10µFC60

1µFC62

0.1µFC64

VCC_ISO_3.3V

TX1

RX1

GND1

T1_OUTR1_IN

GND1

1

2

3

4

5

6

7

8

9

11

10

J10

K202XHT-E9S-N

220R69

EN17

GND12

GND18

GND29

GND215

INA3

INB13

NC5

NC6

NC10

NC12

OUTA14

OUTB4

SEL11

VCC1

VISO16

U8

ISOW7821DWER

1

2

3

J2

5-146278-3

GND

TX1

RX1

ISO_TX1

1

2

3

J16

5-146278-3

GND1

6.3V0.1uF

C76

C1+1

V+2

C1-3

C2+4

C2-5

V-6

DOUT27

RIN28

ROUT29

DIN210

DIN111

ROUT112

RIN113

DOUT114

GND15

VCC16

U6

TRS3232EIPW

220R63

VCC_3.3V

VCC_ISO_3.3V

0.1µFC55

0.1µFC58 0.1µF

C57

0.1µFC56

ISO_RX1

ISO_TX1ISO_RX1

12

3 4

100uH

L11

GND

1 2

34

100uH

L21

GND1

100R64

100 ohmL22

100 ohmL23

100R96





Figure 17. Isolated UART Circuit

3.3.11 Other Interfaces

Figure 18. Pace Detect Module Connector

J9 represents the connection to the pace detection module (TIDA-010005). The pace detection module isinterfaced from the I2C to the main TIDA board. PGAP and PGAN from ADS1292R IC of the TIDA-01614board goes to the pace detection module and detects if any pace pulse is present in the ECG waveformand gives a pace detect to the MCU. Pace reset resets all the counters on the TIDA-010005 board.

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25V

0.1uF

C1

SDA

SCL

ADD0

ADD0

6.98k

R2

6.98k

R1100 ohm

L1

SCL

2ALERT

4

V+

SDA

U1

TMP117AIDRVR

2

4

6

8

10

J1

20021121-00010C4LF

L15

VCC_3.3V

GND

I2C_SDA

I2C_SCL

L16

VCC_3.3V

GND

I2C_SDA

I2C_SCL

L17

VCC_3.3V

GND

I2C_SDA

I2C_SCL5

4

1

2

3

J3

PEC05SAAN

5

4

1

2

3

J4

PEC05SAAN

5

4

1

2

3

J13

PEC05SAAN





Figure 19. Temperature Connector Sensor

Figure 19 shows the connection to the temperature sensor TMP117. Three TMP117 temperature sensorsare used for accurate measurement. Interface is from the I2C to the MCU. ADD0 pin is the fifth pin andconnects to GND, V1, and SDA lines to select the unique slave address.

3.3.12 Temperature Sensor BoardFigure 20 shows the temperature sensor circuit. The TMP117 is a low-power, high-precision temperaturesensor that provides a 16-bit temperature result, with a resolution of 7.8125 m°C, and an accuracy up to±0.1°C with no calibration. The TMP117 operates from 1.8 V to 5.5 V, usually consuming 3.5 µA, andcomes in a 2.00 mm × 2.00 mm WSON package. The device also features integrated EEPROM. Threesuch boards are interfaced to the main TIDA-01614 board to have accurate temperature. Sensor isinterfaced through I2C. This design patch operates on a 3.3-V and uses a 2-layer flex PCB to reducethermal mass and maximize board flexibility. The primary benefit of flexibility is the ease and comfort forthe wearers, which improves the likelihood that the patch remains static on the patient.

U1 is the TMP117 IC and J1 is the connector that interfaces to the TIDA-01614 main board.

Figure 20. Temperature Sensor Circuit

3.3.13 TI DevicesAFE4403The AFE4403 is a fully-integrated analog front-end (AFE) supports pulse oximeter applications. Thedevice consists of a low-noise receiver channel with an integrated analog-to-digital converter (ADC), anLED transmit section, and diagnostics for sensor, and LED fault detection. The device is a configurabletiming controller. This flexibility enables the user to have complete control of the device timingcharacteristics. To ease clocking requirements and provide a low-jitter clock to the AFE4403, an oscillatoris integrated from an external crystal. The device communicates to an external microcontroller or hostprocessor using an SPI interface. The device is a complete AFE solution packaged in a single, compactDSBGA-36 (3.07-mm × 3.07-mm × 0.5-mm) and is specified over the operating temperature range of–20°C to 70°C.

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TLV755PThe TLV755P is an ultra-small, low quiescent current, low-dropout regulator (LDO) that sources 500 mAwith good load and line transient performance. The TLV755P is optimized for a wide variety of applicationsby supporting an input voltage range from 1.45 V–5.5 V. To minimize cost and solution size, the device isoffered in fixed output voltages ranging from 0.6 V to 5 V to support the lower core voltages of modernMCUs. Additionally, the TLV755P has a low-IQ with enable functionality to minimize standby power. Thisdevice features an internal soft-start to lower inrush current, providing a controlled voltage to the load andminimizing the input voltage drop during start up. When shutdown, the device actively pulls down theoutput to quickly discharge the outputs and ensure a known start-up state.

The TLV755P is stable with small ceramic output capacitors allowing for a small overall solution size. Aprecision band-gap and error amplifier provides a typical accuracy of 1%. All device versions haveintegrated thermal shutdown, current limit, and undervoltage lockout (UVLO). The TLV755P has aninternal foldback current limit that helps reduce the thermal dissipation during short-circuit events.

TPS61099The TPS61099x device is a synchronous boost converter with 1-µA ultra-low quiescent current. Thedevice is designed for products powered by an alkaline NiMH rechargeable battery, Lithium-Mn battery, orrechargeable Li-ion battery, for which high efficiency under light load condition is critical to achieve longbattery life operation. The TPS61099x boost converter uses a hysteretic control topology to obtainmaximal efficiency at minimal quiescent current. It only consumes 1-µA quiescent current under a lightload condition and can achieve up to 75% efficiency at 10-µA load with fixed output voltage version. It canalso support up to 300-mA output current from 3.3 V–5 V conversion, and achieve up to 93% at 200-mAload.

The TPS61099x also offers Down Mode and Pass-Through operations for different applications. In DownMode, the output voltage can still be regulated at target values even when input voltage is higher thanoutput voltage. In Pass-Through Mode, the output voltage follows input voltage. The TPS61099x exitsDown Mode and enters into Pass-Through Mode when VIN > VOUT + 0.5 V. The TPS61099x supportstrue shutdown function when it is disabled, which disconnects the load from the input supply to reduce thecurrent consumption. The TPS61099x offers both adjustable output voltage version and fixed outputvoltage versions. It is available in 6-ball 1.23-mm × 0.88-mm WCSP package and 6-pin 2-mm × 2-mmWSON package.

TPS76901The TPS76901 low-dropout (LDO) voltage regulator offers the benefits of low-dropout voltage, ultra-lowpower operation, and miniaturized packaging. This regulator features low-dropout voltages and ultra-lowquiescent current compared to conventional LDO regulators. The TPS76901 device is ideal formicropower operations and where board space is at a premium.

A combination of new circuit design and process innovation has enabled the usual PNP pass transistor tobe replaced by a PMOS pass element. Because the PMOS pass element behaves as a low-value resistor,the dropout voltage is extremely low, and is directly proportional to the load current. Since the PMOS passelement is a voltage-driven device, the quiescent current is ultra-low (28 µA maximum) and is stable overthe entire range of output load current (0 mA to 100 mA). It is intended for use in portable systems suchas laptops and cellular phones. The ultra-low dropout voltage feature and ultra-low power operation resultin a significant increase in system battery operating life. The TPS76901 also features a logic-enabledsleep mode to shut down the regulator, reducing quiescent current to 1 μA, which is typical at TJ = 25°C.The TPS76901 is a variable version programmable over the range of 1.2 V–4.5 V.

TLV62569The TLV62569 device is a synchronous step-down buck DC/DC converter, optimized for high efficiencyand compact solution size. The device integrates switches capable of delivering an output current up to 2A. At medium to heavy loads, the device operates in pulse width modulation (PWM) mode with 1.5-MHzswitching frequency. At light loads, the device automatically enters Power Save Mode (PSM) to maintainhigh efficiency over the entire load current range. In shutdown, the current consumption is reduced to lessthan 2 µA. The TLV62569 provides an adjustable output voltage through an external resistor divider. Aninternal soft start circuit limits the inrush current during startup. Other features like overcurrent protection,thermal shutdown protection, and power good are built-in. The device is available in a SOT23 andSOT563 package.

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BQ24232The BQ2423x devices are highly-integrated Li-ion linear chargers and system power-path managementdevices targeted to space-limited portable applications. The devices operate from either a USB port or ACadapter, and support charge currents between 25 mA and 500 mA. The high-input-voltage range withinput overvoltage protection supports low-cost, unregulated adapters. The USB input current limit accuracyand start-up sequence let the BQ2423x meet the USB-IF inrush current specification. Additionally, theinput dynamic power management (VIN-DPM) prevents the charger from crashing poorly-designed orincorrectly-configured USB sources.

The BQ2423x features dynamic power-path management (DPPM) that powers the system whilesimultaneously and independently charging the battery. The DPPM circuit reduces the charge currentwhen the input current limit causes the system output to fall to the DPPM threshold, thus supplying thesystem load at all times while monitoring the charge current separately. This feature reduces the numberof charge and discharge cycles on the battery, allows proper charge termination, and enables the systemto run with a defective or absent battery pack. Additionally, this enables the system to instantly turn on,even with a totally discharged battery. The power-path management architecture also permits the batteryto supplement the system current requirements when the adapter cannot deliver the peak systemcurrents, enabling the use of a smaller adapter.

The battery is charged in three phases: conditioning, constant current, and constant voltage. In all chargephases, an internal control loop monitors the IC junction temperature and reduces the charge current if theinternal temperature threshold is exceeded. The charger power stage and charge current sense functionsare fully-integrated. The charger function has high-accuracy current and voltage regulation loops, chargestatus display, and charge termination. The input current limit and charge current are programmable usingexternal resistors.

ADS1292RThe ADS1292R is a multichannel, simultaneous sampling, 24-bit, delta-sigma (ΔΣ) analog-to-digitalconverters (ADCs) with a built-in programmable gain amplifier (PGA), internal reference, and an onboardoscillator. The ADS1292R incorporates all features commonly required in portable, low-power medicalECG, sports, and fitness applications.

With high levels of integration and exceptional performance, the ADS1292R enables the creation ofscalable medical instrumentation systems at significantly reduced size, power, and overall cost. TheADS1292R has a flexible input multiplexer per channel that can be independently connected to theinternally-generated signals for test, temperature, and lead-off detection. Additionally, any configuration ofinput channels can be selected for derivation of the right leg drive (RLD) output signal. ADS1292Roperates at data rates up to 8 kSPS. Lead-off detection can be internally implemented to the device, usingthe internal excitation current sink/source from the device. The ADS1292R also includes a fully-integratedrespiration impedance measurement function. The devices are packaged in a 5-mm × 5-mm, 32-pin thinquad flat pack (TQFP). Operating temperature is specified from –40°C to +85°C.

TVS0500The TVS0500 robustly shunts up to 43 A of IEC 61000-4-5 fault current to protect systems from high-power transients or lightning strikes. The device offers a solution to the common industrial signal line EMCrequirement to survive up to 2 kV IEC 61000-4-5 open circuit voltage coupled through a 42 Ω impedance.The TVS0500 uses a unique feedback mechanism to ensure precise flat-clamping during a fault, assuringsystem exposure below 10 V. The tight voltage regulation lets designers confidently select systemcomponents with a lower voltage tolerance, lowering system costs and complexity without sacrificingrobustness. In addition, the TVS0500 is available in a small 2-mm × 2-mm SON footprint, which is ideal forspace-constrained applications. It offers a 70 percent reduction in size compared to industry standardSMA and SMB packages. The extremely-low device leakage and capacitance ensure a minimal effect onthe protected line. To ensure robust protection over the lifetime of the product, TI tests the TVS0500against 5000 repetitive surge strikes at high-temperatures with no shift in device performance.

MSP432P4011The SimpleLink™ MSP432P401x MCUs are optimized host MCUs with an integrated 16-bit precisionADC. These MCUs deliver ultra-low power performance including 80 µA/MHz in active power and 660 nAin standby power with FPU and DSP extensions. As an optimized host MCU, the MSP432P401x letsdevelopers add high-precision analog and memory extension to applications based on SimpleLinkconnectivity solutions.

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The MSP432P401x devices are part of the SimpleLink MCU platform, consisting of Wi-Fi®, Bluetooth®low-energy, Sub-1 GHz, and host MCUs. These share a common, easy-to-use development environmentwith a single core software development kit (SDK) and rich tool set. A one-time integration of theSimpleLink platform lets you add any combination of devices from the portfolio into your design. Theultimate goal of the SimpleLink platform is to achieve 100% code reuse when your design requirementschange. For more information, see the SimpleLink website.

MSP432P401x devices are supported by a comprehensive ecosystem of tools, software, documentation,training, and support to get your development started quickly. The MSP-EXP432P401R LaunchPaddevelopment kit or MSP-TS432PZ100 target socket board (with additional MCU sample) along with thefree SimpleLink MSP432 SDK is all you need to get started.

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http://www.ti.com/simplelink

JTAG Connector (J8)

Pace Detection Module Connector

(J9)

Temperature Sensors Expansion Slot for BLE/WiFi/ Sub 1 GHz

(J11 and J2)

Battery Connector (J7)

InputPower (J6)

SPO2 Finger Clip Connector (J5)

ECG Electrode Connector (J15)

UART Connector (J10)

www.ti.com Hardware, Software, Testing Requirements, and Test Results




4 Hardware, Software, Testing Requirements, and Test Results

4.1 Required Hardware and Software

4.1.1 HardwareHardware connectionFigure 21 and Figure 22 show top and bottom views of the TIDA-01614 PCB.

Figure 21. TIDA-01614 PCB Connector Configuration – Top View

Figure 22. TIDA-01614 PCB Connector Configuration – Bottom View

The following list provides information about each part:• Input Power Connector (J6): A USB-connector for 5-V input power 5 V. 5 V is derived from the USB

Vbus.• Battery Connector (J7): This pin connects the rechargeable 3.7-V Lithium-ion battery.

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ECG Simulator

ECG ElectrodeConnector

(J15) 3.7 Li-ion Battery

JTAG Cable

SPO2 Finger Clip MSP432 LaunchPad

UART to USB Dongle

Temperature Sensors

Hardware, Software, Testing Requirements, and Test Results www.ti.com




• UART Connector (J10): This connector is given as a provision to connect to the PC through serialport.

• ECG Electrode Connector (J15): This pin connects the ECG electrodes in 2 electrode and 3electrode operations.

• Temperature Sensor Connector (J3,J4 and J13): These connectors connect the three temperaturesensors.

• SPO2 Finger Clip Connector (J5): This connector connects the SPO2 finger clip.• Expansion Slot for BLE/WiFi/Sub 1 GHz (J11 and J12): These connectors are the expansion slot for

BLE/WiFi/Sub 1 GHz.• JTAG Connector (J8): The JTAG connector is for programming.• Pace Detection Module connector (J9): This connector connects the pace detection Module (TIDA-

010005).• Isolated UART connector (J16) : This connector is used to give the provision to have 3.3 V isolated

UART signals. Connect the USB to UART Dongle (C232HD-DDHSP-0) from this connector to the PC.

4.1.2 Test SetupFigure 23 shows the test setup. An ECG simulator (Datrend AMPS-1 Advanced Modular PatientSimulator) generates ECG, Respiration, and pace signal for testing. The TIDA-01614 board isprogrammed using the MSP432 launch pad, connecting to the PC. Three temperature sensor Flex PCBsare connected to this board. Flexi PCB can be easily strapped on to the human board for temperaturemeasurement. Three such temperature sensors are used for accurate temperature measurement. ThreeECG electrodes connected to the right arm, left arm, and right leg attach to this board using J15connector. The system runs with a rechargeable 3.7-V 500 mAh Li-ion battery connected to J7 connector.C232HD – DDHSP-0 UART to USB serial cable is used for UART communication to the PC and GUI.

Figure 23. TIDA-01614 Test Setup

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4.1.3 SoftwareThe following software tools are used to test and obtain the results for this TI reference design:• Code Composer Studio™, version 8 or higher. This software must be installed with MSP432P401

support.• SimpleLink-MSP432P401-SDK Software. You can download it at http://www.ti.com/tool/simplelink-

msp432-sdk.• GUI Composer Run Time Engine. You can download it at http://software-dl.ti.com/ccs/non-

esd/gui_composer/runtime/gcruntime-7.0.0-windows-installer.exe .

The following instructions assume that Code Composer Studio is installed on the PC. Download the GUIComposer application setup (zip file) and TIDA-01614 firmware (zip file) from the TIDA-01614 productpage. Follow these instructions to download the software loading for the TIDA-01614 board:1. Plug in the MSP EXP432P401R board on the USB port of the PC. Section 4.1.2 shows the setup.

Table 2 lists the connections between the TIDA-01614 board and the MSP EXP432P401R) board.2. Open Code Composer Studio as administrator.

a. Right click on the CCS icon and run as administrator.3. Click on the Project option in the main toolbar.4. Click Import CCS projects.5. Select the installed firmware (Default: C:\Program Files (x86)\Texas Instruments\TIDA01614\TIDA-

01614_firmware).6. Import all projects.7. Click the OK button.8. Click View.9. Click Project Explorer.10. Select TIDA-01614 firmware.11. Click on the Run and Debug buttons, which program the board with the selected project file.

Go to https://dev.ti.com/gallery/info/5331888/med_tida01614/ver/1.0.1/ for the GUI composer. You mustuse Google Chrome to open the link. Use the following steps for the GUI composer.

Figure 24. Step 1

1. Click anywhere inside the card. A pop-up appears to download and install the TI cloud agent. Install itand click to finish.

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http://www.ti.com/tool/simplelink-msp432-sdk

http://www.ti.com/tool/simplelink-msp432-sdk

http://software-dl.ti.com/ccs/non-esd/gui_composer/runtime/gcruntime-7.0.0-windows-installer.exe

http://software-dl.ti.com/ccs/non-esd/gui_composer/runtime/gcruntime-7.0.0-windows-installer.exe

https://dev.ti.com/gallery/info/5331888/med_tida01614/ver/1.0.1/





Figure 25. Step 2

2. Click on the Quick Start button.

Figure 26. Step 3

3. Go to the Options tab.4. Select 460800 as the baud rate and select the COM port for the USB to UART Dongle.5. Click on the Start Monitoring button. Ensure that it shows that the hardware is connected on the bottom

panel.

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4.2 Test Results

4.2.1 Test Results

Figure 27. GUI Displaying ECG, SPO2 Waveforms With SPO2 Number and Heart Rate With ECGSensitivity of 100-µVs

Figure 27 illustrates the GUI displaying ECG, SPO2 waveforms with SPO2 number, and heart rate withECG sensitivity of 100-µVs.

Figure 28. GUI Displaying ECG, Respiration and SPO2 Waveforms With SPO2 Number and Heart Rate

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Figure 29. GUI Showing the Pacemaker Detection

Figure 29 illustrates the GUI showing the pacemaker detection. This result is captured with the respirationoff.

Figure 30. Output Ripple Voltage of 5.2 V Supply for Input Voltage of 3.7 V, and Input Current of 120 mA

Figure 30 shows the output ripple voltage of 5.2 V supply with input voltage of 3.7 V, and input current of120 mA.

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Figure 31. Output Ripple Voltage of 5 V Supply for Input Voltage of 3.7 V, and Input Current of 120 mA

Figure 31 shows the output ripple voltage of 5 V supply for input voltage of 3.7 V, and input current of 120mA.


Figure 32 shows the output ripple voltage of 3.3 V supply for input voltage of 3.7 V, and input current of120 mA.

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Figure 33 shows the output ripple voltage of 3 V supply for input voltage of 3.7 V, and input current of 120mA.

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www.ti.com Design Files




5 Design Files

5.1 SchematicsSee the design files at TIDA-01614 to download the schematics.

5.2 Bill of MaterialsSee the design files at TIDA-01614 to download the bill of materials (BOM).

5.3 PCB Layout Recommendations

5.3.1 Layout PrintsSee the design files at TIDA-01614 to download the layer plots.

5.4 Altium ProjectSee the design files at TIDA-01614 to download the Altium Designer® project files.

5.5 Gerber FilesSee the design files at TIDA-01614 to download the Gerber files.

5.6 Assembly DrawingsSee the design files at TIDA-01614 to download the assembly drawings.

6 Software FilesSee the design files at TIDA-01614 to download the software files.

7 Related Documentation1. Texas Instruments, Minaturized pulse oximeter reference design getting started guide2. Texas Instruments, How to design peripheral oxygen saturation (SpO2) and optical heart rate

monitoring (OHRM) systems using the AFE4403 application report3. Texas Instruments, Understanding lead-off detection in ECG application report

7.1 TrademarksE2E, Code Composer Studio are trademarks of Texas Instruments.Altium Designer is a registered trademark of Altium LLC or its affiliated companies.SimpleLink is a trademark of other.All other trademarks are the property of their respective owners.

7.2 Third-Party Products DisclaimerTI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOESNOT CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS ORSERVICES OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS ORSERVICES, EITHER ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.

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http://www.ti.com/lit/pdf/TIDU475

http://www.ti.com/lit/pdf/SLAA655

http://www.ti.com/lit/pdf/SLAA655

http://www.ti.com/lit/pdf/SBAA196

About the Author www.ti.com




8 About the AuthorLENI SKARIAH is a systems engineer at Texas Instruments, where she is responsible for developingsubsystem design solutions for the Medical, Healthcare, and Fitness sector. Leni brings her experience inprecision analog and mixed signal designs to this role. Leni earned her Bachelor of Technology inElectronics and Communication Engineering from the University of Kannur and her Master of Technologyin Digital Electronics and Communication Systems from Visvesvaraya Technological University,Karnataka.

SANJAY DIXIT is a system architect in the Industrial Systems-Medical Healthcare and Fitness Sector atTexas Instruments where he is responsible for specifying reference designs.

KIRAN RAJMOHAN is a test engineer at Texas Instruments, where he is responsible for testing andcharacterization of high-performance analog IPs like ADC, DAC, PGA, PLL, and RF-signal chains in TImicrocontrollers. Kiran has been with TI since 2015. Kiran earned his Bachelor of Technology inElectronics and Communication Engineering at the College of Engineering, Trivandrum, Kerala.

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Revision History

Revision HistoryNOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Original (March 2019) to A Revision ....................................................................................................... Page

• Changed TIDA-01614 Block Diagram image in System Overview and on first page ............................................ 5

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Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265Copyright © 2019, Texas Instruments Incorporated

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