mcp73871 cargador

MCP73871Stand-Alone System Load Sharing and Li-Ion / Li-Polymer

Battery Charge Management Controller

Features• Integrated System Load Sharing and Battery

Charge Management- Simultaneously Power the System and

Charge the Li-Ion Battery- Voltage Proportional Current Control (VPCC)

ensures system load has priority over Li-Ion battery charge current

- Low-Loss Power-Path Management with Ideal Diode Operation

• Complete Linear Charge Management Controller- Integrated Pass Transistors- Integrated Current Sense- Integrated Reverse Discharge Protection- Selectable Input Power Sources: USB Port or

AC-DC Wall Adapter• Preset High Accuracy Charge Voltage Options:

- 4.10V, 4.20V, 4.35V or 4.40V- ±0.5% Regulation Tolerance

• Constant Current / Constant Voltage (CC/CV) Operation with Thermal Regulation

• Maximum 1.8A Total Input Current Control• Resistor Programmable Fast Charge Current

Control: 50 mA to 1A• Resistor Programmable Termination Set Point• Selectable USB Input Current Control

- Absolute Maximum: 100 mA (L) / 500 mA (H)• Automatic Recharge• Automatic End-of-Charge Control• Safety Timer With Timer Enable/Disable Control• 0.1C Preconditioning for Deeply Depleted Cells• Battery Cell Temperature Monitor• Undervoltage Lockout (UVLO)• Low Battery Status Indicator (LBO)• Power-Good Status Indicator (PG)• Charge Status and Fault Condition Indicators• Numerous Selectable Options Available for a

Variety of Applications:- Refer to Section 1.0 “Electrical

Characteristics” for Selectable Options”- Refer to the “Product Identification

System” for Standard Options• Temperature Range: -40°C to +85°C• Packaging: 20-Lead QFN (4 mm x 4 mm)

Applications• GPSs / Navigators• PDAs and Smart Phones• Portable Media Players and MP3 Players• Digital Cameras• Bluetooth Headsets• Portable Medical Devices• Charge Cradles / Docking Stations• Toys

DescriptionThe MCP73871 device is a fully integrated linearsolution for system load sharing and Li-Ion / Li-Polymerbattery charge management with ac-dc wall adapterand USB port power sources selection. It’s alsocapable of autonomous power source selectionbetween input or battery. Along with its small physicalsize, the low number of required external componentsmakes the device ideally suited for portableapplications.

The MCP73871 device automatically obtains power forthe system load from a single-cell Li-Ion battery or aninput power source (ac-dc wall adapter or USB port).The MCP73871 device specifically adheres to thecurrent drawn limits governed by the USB specification.With an ac-dc wall adapter providing power to thesystem, an external resistor sets the magnitude of 1Amaximum charge current while supports up to 1.8Atotal current for system load and battery chargecurrent.

The MCP73871 device employs a constant current /constant voltage (CC/CV) charge algorithm withselectable charge termination point. The constantvoltage regulation is fixed with four available options:4.10V, 4.20V, 4.35V, or 4.40V to accommodate new,emerging battery charging requirements. TheMCP73871 device also limits the charge current basedon die temperature during high power or high ambientconditions. This thermal regulation optimizes thecharge cycle time while maintaining device reliability.

The MCP73871 device includes a low battery indicator,a power-good indicator and two charge statusindicators that allows for outputs with LEDs orcommunication with host microcontrollers. TheMCP73871 device is fully specified over the ambienttemperature range of -40°C to +85°C.

© 2009 Microchip Technology Inc. DS22090B-page 1

MCP73871
Package Types
Typical Application Circuit

IN S

TAT1

/ LB

OPG

THERM

MCP73871 20-Lead QFN

STA

T2

PROG1

IN

OUT

OU

T

CE

SEL

PROG3

TE

VBATVBATVPCC

VSS

VS

SV B

AT_S

EN

SE

2EP

201

19 18 17

3

4 1211

109

5

6 7 8

1314

15

16

21PROG2

STAT1 LBO

IN OUT

PG

VBAT

Single-Cell Li-Ion Battery

7

MCP73871 Typical Application

1, 20

8

18, 19

10 µF

10, 11, EP

Ac-dc Adapter or USB Port

STAT2THERM

VSS

PROG1

PROG3 12

13 RPROG1

6

5

14, 15, 16

470Ω

470Ω

470Ω

2 4.7 µF

System Load

SEL

TE

PROG2

HiLow

HiLow

HiLow

3

4

9

RPROG3

VPCC

NTC

10 kΩ

HiLow17

CE

4.7 µF

DS22090B-page 2 © 2009 Microchip Technology Inc.

MCP73871
Functional Block Diagram
STAT1

PROG1

VBAT

G=0.001

VSS

DirectionControl

TERM

+-

+-

LTVT

+-

HTVT

THERM

50 µA

UVLO, REFERENCE,CHARGE CONTROL, TIMER, AND STATUS LOGIC

STAT2

PG

DirectionControl

G=0.001

G=0.001

PROG2

IN

+-

CURRENT LIMIT

VREF

G=0.001

+-

CURRENT LIMIT

VREF/2

PROG3

+-

CA

VREF

PRECONDITION

+- VREF

+-

VA

VREF

VREF

SEL

OUT

VREF

TE

0.2Ω

0.2Ω Ideal Diode, SynchronousSwitch

CHRG

+- VREF

+-

VREFVPCC

CE

VBAT_SENSE


MCP73871
NOTES:

MCP73871

1.0 ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings†VIN....................................................................................7.0VAll Inputs and Outputs w.r.t. ................ VSS-0.3V to VDD+0.3V(VDD = VIN or VBAT)Maximum Junction Temperature, TJ ............ Internally LimitedStorage temperature .....................................-65°C to +150°CESD protection on all pinsHuman Body Model (1.5 kΩ in Series with 100pF) ........≥ 4 kVMachine Model (200 pF, No Series Resistance) .............300V

† Notice: Stresses above those listed under “MaximumRatings” may cause permanent damage to the device. This isa stress rating only and functional operation of the device atthose or any other conditions above those indicated in theoperational listings of this specification is not implied.Exposure to maximum rating conditions for extended periodsmay affect device reliability.

DC CHARACTERISTICSElectrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40°C to +85°C.Typical values are at +25°C, VIN = [VREG (typical) + 1.0V]

Parameters Sym Min Typ Max Units Conditions

Supply InputSupply Voltage VIN VREG

+0.3V— 6 V

Supply Current ISS — 2500 3750 µA Charging— 260 350 µA Charge Complete— 180 300 µA Standby— 28 50 µA Shutdown

(VDD < VBAT - 100 mV or VDD < VSTOP)

UVLO Start Threshold VSTART VREG + 0.05V

VREG + 0.15V

VREG + 0.25V

V VDD= Low-to-High

UVLO Stop Threshold VSTOP VREG – 0.07V

VREG + 0.07V

VREG + 0.17V

V VDD= High-to-Low

UVLO Hysteresis VHYS — 90 — mVVoltage Regulation (Constant Voltage Mode)Regulated Charge Voltage VREG 4.080 4.10 4.121 V VDD=[VREG(typical)+1V]

4.179 4.20 4.221 V IOUT=10 mA 4.328 4.35 4.372 V TA=-5°C to +55°C4.378 4.40 4.422

Regulated Charge Voltage Tolerance VRTOL -0.5 — +0.5 % TA= +25°C-0.75 — +0.75 % TA= -5°C to +55°C

Line Regulation |(ΔVBAT/VBAT)/ΔVDD|

— 0.08 0.20 %/V VDD=[VREG(typical)+1V] to 6VIOUT=10 mA

Load Regulation |ΔVBAT/VBAT| — 0.08 0.18 % IOUT=10 mA to 150 mAVDD= [VREG(typical)+1V]

Supply Ripple Attenuation PSRR — -47 — dB IOUT=10 mA, 1 kHz— -40 — dB IOUT=10 mA, 10 kHz

Current Regulation (Fast Charge Constant-Current Mode)AC-Adapter Fast Charge Current IREG 90 100 110 mA PROG1 = 10 kΩ

900 1000 1100 mA PROG1 = 1 kΩ,

TA=-5°C to +55°C, SEL = HiUSB Fast Charge Current IREG 80 90 100 mA PROG2 = Low, SEL = Low,

(Note 2)400 450 500 mA PROG2 = High, SEL = Low,

(Note 2)TA= -5°C to +55°C

Note 1: The value is ensured by design and not production tested.2: The maximum available charge current is also limited by the value set at PROG1 input.


MCP73871

Input Current Limit Control (ICLC)USB-Port Supply Current Limit ILIMIT_USB 80 90 100 mA PROG2 = Low, SEL = Low

400 450 500 mA PROG2 = High, SEL = LowTA=-5°C to +55°C

AC-DC Adapter Current Limit ILIMIT_AC 1500 1650 1800 mA SEL = High, TA=-5°C to +55°CVoltage Proportional Charge Control (VPCC - Input Voltage Regulation)VPCC Input Threshold VVPCC — 1.23 — V IOUT=10 mAVPCC Input Threshold Tolerance VRTOL -3 — +3 % TA=-5°C to +55°CInput Leakage Current ILK — 0.01 1 µA VVPCC = VDD

Precondition Current Regulation (Trickle Charge Constant-Current Mode)Precondition Current Ratio IPREG / IREG 7.5 10 12.5 % PROG1 = 1.0 kΩ to 10 kΩ

TA=-5°C to +55°CPrecondition Current Threshold Ratio VPTH / VREG 69 72 75 % VBAT Low-to-HighPrecondition Hysteresis VPHYS — 105 — mV VBAT High-to-LowAutomatic Charge Termination Set PointCharge Termination Current Ratio ITERM 75 100 125 mA PROG3 = 10 kΩ

7.5 10 12.5 mA PROG3 = 100 kΩTA=-5°C to +55°C

Automatic RechargeRecharge Voltage Threshold Ratio VRTH VREG -

0.21VVREG - 0.15V

VREG - 0.09V

V VBAT High-to-Low

IN-to-OUT Pass Transistor ON-ResistanceON-Resistance RDS_ON — 200 — mΩ VDD = 4.5V, TJ = 105°CCharge Transistor ON-ResistanceON-Resistance RDSON_ — 200 — mΩ VDD = 4.5V, TJ = 105°CBAT-to-OUT Pass Transistor ON-ResistanceON-Resistance RDS_ON — 200 — mΩ VDD = 4.5V, TJ = 105°CBattery Discharge CurrentOutput Reverse Leakage Current IDISCHARGE — 30 40 µA Shutdown

(VBAT < VDD < VUVLO)— 30 40 µA Shutdown (0 < VDD < VBAT)— 30 40 µA VBAT = Power Out, No Load— -6 -13 µA Charge Complete

Status Indicators - STAT1 (LBO), STAT2, PGSink Current ISINK — 16 35 mALow Output Voltage VOL — 0.4 1 V ISINK = 4 mAInput Leakage Current ILK — 0.01 1 µA High Impedance, VDD on pinLow Battery Indicator (LBO)Low Battery Detection Threshold VLBO — Disable — VBAT > VIN, PG = Hi-Z

2.85 3.0 3.15 V TA=-5°C to +55°C2.95 3.1 3.25 V3.05 3.2 3.35 V

Low Battery Detection Hysteresis VLBO_HYS — 150 — mV VBAT Low-to-High

DC CHARACTERISTICS (CONTINUED)Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40°C to +85°C.Typical values are at +25°C, VIN = [VREG (typical) + 1.0V]




MCP73871

PROG1 Input (PROG1)Charge Impedance Range RPROG 1 — 20 kΩ

PROG3 Input (PROG3)Termination Impedance Range RPROG 5 — 100 kΩ

PROG2 Input (PROG2)Input High Voltage Level VIH 1.8 — — VInput Low Voltage Level VIL — — 0.8 VInput Leakage Current ILK — 0.01 1 µA VPROG2 = VDD

Timer Enable (TE)Input High Voltage Level VIH 1.8 — — V Note 1Input Low Voltage Level VIL — — 0.8 V Note 1Input Leakage Current ILK — 0.01 1 µA VTE = VDD

Chip Enable (CE)Input High Voltage Level VIH 1.8 — — VInput Low Voltage Level VIL — — 0.8 VInput Leakage Current ILK — 0.01 1 µA VCE = VDD

Input Source Selection (SEL)Input High Voltage Level VIH 1.8 — — VInput Low Voltage Level VIL — — 0.8 VInput Leakage Current ILK — 0.01 1 µA VSEL = VDD

Thermistor BiasThermistor Current Source ITHERM 47 50 53 µA 2 kΩ < RTHERM < 50 kΩ

Thermistor ComparatorUpper Trip Threshold VT1 1.20 1.24 1.26 V VT1 Low-to-HighUpper Trip Point Hysteresis VT1HYS — -40 — mVLower Trip Threshold VT2 0.23 0.25 0.27 V VT2 High-to-LowLower Trip Point Hysteresis VT2HYS — 40 — mVThermal ShutdownDie Temperature TSD — 150 — °CDie Temperature Hysteresis TSDHYS — 10 — °C

DC CHARACTERISTICS (CONTINUED)Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40°C to +85°C.Typical values are at +25°C, VIN = [VREG (typical) + 1.0V]




MCP73871
AC CHARACTERISTICS
TEMPERATURE SPECIFICATIONS

Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = 4.6V to 6V.Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]


UVLO Start Delay tSTART — — 5 ms VDD Low-to-HighCurrent RegulationTransition Time Out of Precondition tDELAY — — 10 ms VBAT < VPTH to VBAT > VPTH

Current Rise Time Out of Precondition tRISE — — 10 ms IOUT Rising to 90% of IREG

Precondition Comparator Filter Time tPRECON 0.4 1.3 3.2 ms Average VBAT Rise/FallTermination Comparator Filter Time tTERM 0.4 1.3 3.2 ms Average IOUT FallingCharge Comparator Filter Time tCHARGE 0.4 1.3 3.2 ms Average VBAT FallingThermistor Comparator Filter Time tTHERM 0.4 1.3 3.2 ms Average THERM Rise/FallElapsed TimerElapsed Timer Period tELAPSED — 0 — Hours

3.6 4.0 4.4 Hours5.4 6.0 6.6 Hours7.2 8.0 8.8 Hours

Status IndicatorsStatus Output Turn-off tOFF — — 500 µs ISINK = 1 mA to 0 mAStatus Output Turn-on tON — — 500 µs ISINK = 0 mA to 1 mANote 1: Internal safety timer is tested base on internal oscillator frequency measurement.

Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = 4.6V to 6V.Typical values are at +25°C, VDD = [VREG (typical) + 1.0V]


Temperature RangesSpecified Temperature Range TA -40 — +85 °COperating Temperature Range TJ -40 — +125 °CStorage Temperature Range TA -65 — +150 °CThermal Package ResistancesThermal Resistance, 20LD-QFN, 4x4 θJA — 35 — °C/W 4-Layer JC51-7 Standard Board,

Natural Convection


MCP73871

2.0 TYPICAL PERFORMANCE CURVES

Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25°C, Constant-voltage mode.

FIGURE 2-1: Battery Regulation Voltage (VBAT) vs. Supply Voltage (VDD).

FIGURE 2-2: Battery Regulation Voltage (VBAT) vs. Ambient Temperature (TA).

FIGURE 2-3: Charge Current (IOUT) vs. Programming Resistor (RPROG).

FIGURE 2-4: Charge Current (IOUT) vs. Battery Regulation Voltage (VBAT).

FIGURE 2-5: Output Leakage Current (IDISCHARGE) vs. Ambient Temperature (TA).

FIGURE 2-6: Output Leakage Current (IDISCHARGE) vs. Battery Regulation Voltage (VBAT).

Note: The graphs and tables provided following this note are a statistical summary based on a limited number ofsamples and are provided for informational purposes only. The performance characteristics listed hereinare not tested or guaranteed. In some graphs or tables, the data presented may be outside the specifiedoperating range (e.g., outside specified power supply range) and therefore outside the warranted range.

4.176

4.184

4.192

4.200

4.208

4.216

4.224

4.232

4.240

4.6 4.9 5.1 5.4 5.6 5.9Supply Voltage (V)

Bat

tery

Reg

ulat

ion

Volta

ge (V

) Temperature = +25°C

IOUT= 100 mA

IOUT= 500 mA

IOUT= 900 mA

IOUT= 10 mA

4.190

4.198

4.206

4.214

4.222

4.230

4.238

-45 -30 -15 0 15 30 45 60 75 90Ambient Temperature (°C)

Bat

tery

Reg

ulat

ion

Vol

tage

(V)

IOUT = 10 mA

IOUT = 100 mA

IOUT = 500 mA

IOUT = 1000 mA

0100200300400500600700800900

1000

1 2 3 4 5 6 7 8 9 1011121314151617181920RPROG (kΩ)

I REG

(mA

)

VDD= 5.2V Temperature = +25°C

4.1004.1204.1404.1604.1804.2004.2204.2404.2604.2804.300

0

100

200

300

400

500

600

700

800

900

1000

Charge Current (mA)

Bat

tery

Reg

ulat

ion

Vol

tage

(V

)

Temperature = +25°CVDD = 5.2V

10.0

15.0

20.0

25.0

30.0

35.0

40.0

-45 -30 -15 0 15 30 45 60 75 90Temperature (°C)

Bat

tery

Dis

char

ge C

urre

nt

(µA

)VBAT = 4.2VVDD= Floating

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

3.0 3.2 3.4 3.6 3.8 4.0 4.2Battery Voltage (V)

Bat

tery

Dis

char

ge C

urre

nt

(µA

)

VDD= VBATTemperature = +25°C


MCP73871
FIGURE 2-7: Output Leakage Current (IDISCHARGE) vs. Battery Voltage (VBAT).

FIGURE 2-8: Charge Current (IOUT) vs. Supply Voltage (VDD).



FIGURE 2-11: Charge Current (IOUT) vs. Ambient Temperature (TA).


0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

3.0 3.2 3.4 3.6 3.8 4.0 4.2Battery Voltage (V)

Bat

tery

Dis

char

ge C

urre

nt

(µA

)

VDD= FloatingTemperature = +25°C

800830860890920950980

1010104010701100113011601190

4.5 4.8 5.0 5.3 5.5 5.8 6.0Supply Voltage (V)

I REG

(mA

)

RPROG = 1 kΩTemperature = +25°C

450460470480490500510520530540550

4.5 4.8 5.0 5.3 5.5 5.8 6.0Supply Voltage (V)

I REG

(mA

)


9092949698

100102104106108110

4.5 4.8 5.0 5.3 5.5 5.8 6.0Supply Voltage (V)

I RE

G (m

A)


700740780820860900940980

102010601100


Cha

rge

Cur

rent

(mA

)

RPROG = 1 kΩVDD = 5.2V

9092949698

100102104106108110


Cha

rge

Cur

rent

(mA

)



MCP73871

FIGURE 2-14: Charge Current (IOUT) vs. Junction Temperature (TJ).



FIGURE 2-17: Thermistor Current (ITHERM) vs. Supply Voltage (VDD).

FIGURE 2-18: Thermistor Current (ITHERM) vs. Ambient Temperature (TA).

41

43

45

47

49

51

53

55


Cha

rge

Cur

rent

(mA

)


0

200

400

600

800

1000

1200

25 50 75 100 125 150Ambient Temperature (°C)

Cha

rge

Cur

rent

(mA

)

VDD = 5.2VRPROG = 1 kΩ

0

100

200

300

400

500

600


Cha

rge

Cur

rent

(mA

)


0

20

40

60

80

100

120


Cha

rge

Cur

rent

(mA

)


47.047.548.048.549.049.550.050.551.051.552.0

4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0Supply Voltage (V)

Ther

mis

tor

Cur

rent

(µA

) Temperature = +25°C

47.047.548.048.549.049.550.050.551.051.552.0


Ther

mis

tor C

urre

nt (µ

A) VDD = 5.2V


MCP73871
FIGURE 2-19: Power Supply Ripple Rejection (PSRR).

FIGURE 2-20: Line Transient Response. IOUT = 100 mA.

FIGURE 2-21: Line Transient Response. IOUT = 500 mA.

FIGURE 2-22: Load Transient Response. IOUT = 100 mA.

FIGURE 2-23: Load Transient Response. IOUT = 500 mA.

FIGURE 2-24: Undervoltage Lockout.

-60

-50

-40

-30

-20

-10

0

0.01 0.1 1 10 100 1000Frequency (kHz)

PSR

R (d

B)

IOUT = 10 mA

4.55

5.56

6.57

7.58

8.59

-0.0008 -0.0006 -0.0004 -0.0002 0 0.0002

Time (s)

Out

put V

olta

ge (V

)

-0.7

-0.5

-0.3

-0.1

0.1

0.3

Out

put C

urre

nt (A

)

IOUT = 100 mA

44.5

55.5

66.5

77.5

88.5

9

-0.0008 -0.0006 -0.0004 -0.0002 0 0.0002Time (s)

Out

put V

olta

ge (V

)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Out

put C

urre

nt (A

)

IOUT = 500 mA

-0.20

0.20.40.60.8

11.21.41.61.8

-0.001 0 0.001 0.002 0.003 0.004

Time (s)

Out

put C

urre

nt (A

)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

Out

put R

ippl

e (V

)

IOUT = 100 mA

-0.20

0.20.40.60.8

11.21.41.61.8

0.0007

5

0.001

15

0.0015

5

0.001

95

0.002

35

0.0027

5

Time (s)

Out

put C

urre

nt (A

)

-0.5-0.4-0.3-0.2-0.100.10.2

Out

put R

ippl

e (V

)IOUT = 500 mA

Inpu

t Vol

tage

(V)

UVL

O (V

)

Time (ms)


MCP73871
FIGURE 2-25: Startup Delay.

FIGURE 2-26: Complete Charge Cycle (130 mAh Li-Ion Battery).

FIGURE 2-27: Complete Charge Cycle (1000 mAh Li-Ion Battery).

FIGURE 2-28: Typical Charge Profile in Preconditioning (1000 mAh Battery).

Inpu

t Vol

tage

(V)

Star

tup

Volta

ge (V

)

Time (ms)

00.5

11.5

22.5

33.5

44.5

0 0.1 0.2 0.3 0.4 0.5

Time (Minutes)

Cha

rge

Volta

ge (V

)

0

0.1

0.2

0.3

0.4

0.5C

harg

e C

urre

nt (A

)

MCP73871VDD = 5.2VSEL = LowPROG2 = Low

00.5

11.5

22.5

33.5

44.5

0 10 20 30 40 50 60 70 80

Time (Minute)

Cha

rge

Vol

tage

(V)

00.20.40.60.811.21.41.61.82

Cha

rge

Cur

rent

(A)

MCP73871VDD = 5.2VRPROG1 = 1 kΩRPROG3 = 25 kΩ

00.5

11.5

22.5

33.5

44.5

0 0.2 0.4 0.6 0.8 1Time (Minute)

Cha

rge

Vol

tage

(V)

00.20.40.60.811.21.41.61.82

Cha

rge

Cur

rent

(A)

Preconditioning

Preconditioning Threshold Voltage

Fast Charge (Constant Current)



MCP73871
NOTES:

MCP73871

3.0 PIN DESCRIPTIONThe descriptions of the pins are listed in Table 3-1.

TABLE 3-1: PIN FUNCTION TABLES

3.1 Power Supply Input (IN)A supply voltage of VREG + 0.3V to 6V isrecommended. Bypass to VSS with a minimum of4.7 µF.

3.2 System Output Terminal (OUT)The MCP73871 device powers the system via outputterminals while independently charging the battery.This feature reduces the charge and discharge cycleson the battery, allows for proper charge termination andthe system to run with an absent or defective batterypack. Also, this feature gives the system priority oninput power, allowing the system to power-up withdeeply depleted battery packs. Bypass to VSS with aminimum of 4.7 µF is recommended.

3.3 Voltage Proportional Charge Control (VPCC)

If the voltage on the IN pin drops to a preset value,determined by the threshold established at the VPCCinput, due to a limited amount of input current or inputsource impedance, the battery charging current isreduced. Further demand from the system is supportedby the battery, if possible. To active this feature, simplysupply 1.23V or greater to VPCC pin. This feature canbe disabled by connecting the VPCC pin to IN.

For example, a system is designed with a 5.5V ratedDC power supply with ±0.5V tolerance. The worstcondition of 5V is selected, which is used to calculatethe VPCC supply voltage with divider.

Pin Number Symbol I/O Function

1, 20 OUT O System Output Terminal2 VPCC I Voltage proportional charge control3 SEL I Input type selection (Low for USB port, High for ac-dc adapter)4 PROG2 I USB port input current limit selection when SEL = Low.

(Low = 100 mA, High = 500 mA)5 THERM I/O Thermistor monitoring input and bias current6 PG O Power-Good Status Output (Open-Drain)7 STAT2 O Charge Status Output 2 (Open-Drain)8 STAT1 /

LBOO Charge Status Output 1 (Open-Drain). Low battery output indicator when

VBAT > VIN9 TE I Timer Enable; Enables Safety Timer when active Low

10, 11, EP VSS — Battery Management 0V Reference. EP (Exposed Thermal Pad); There is an internal electrical connection between the exposed thermal pad and VSS. The EP must be connected to the same potential as the VSS pin on the Printed Circuit Board (PCB)

12 PROG3 I/O Termination set point for both ac-dc adapter and USB port13 PROG1 I/O Fast charge current regulation setting with SEL = High. Preconditioning set point

for both USB port and ac-dc adapter.14, 15 VBAT I/O Battery Positive Input and Output connection

16 VBAT_SENSE I/O Battery Voltage Sense17 CE I Device Charge Enable; Enabled when CE = High

18, 19 IN I Power Supply Input.Legend: I = Input, O = Output, I/O = Input/Output

Note: The input pins should always tie to either High or Low, and never allow floating to ensure operation properly.


MCP73871
The voltage divider equation is shown below:
The calculated R1 equals to 337.2 kΩ when 110 kΩ isselected for R2. The 330 kΩ resistor is selected for R1to build the voltage divider for VPCC.

FIGURE 3-1: Voltage Divider Example.

3.4 Input Source Type Selection (SEL)The input source type selection (SEL) pin is used toselect input power source for input current limit controlfeature. With the SEL input High, the MCP73871device is designed to provide a typical 1.65A to systempower and charge Li-Ion battery from a regular 5V walladapter. The MCP73871 device limits the input currentup to 1.8A. When SEL active Low, the input source isdesigned to provide system power and Li-Ion batterycharging from a USB Port input while adhering to thecurrent limits governed by the USB specification.

3.5 Battery Management 0V Reference (VSS)

Connect to negative terminal of battery, system loadand input supply.

3.6 Battery Charge Control Output (VBAT)

Connect to positive terminal of Li-Ion / Li-Polymerbatteries. Bypass to VSS with a minimum of 4.7 µF toensure loop stability when the battery is disconnected.

3.7 Battery Voltage Sense (VBAT_SENSE)

Connect to positive terminal of battery. A precisioninternal voltage sense regulates the final voltage onthis pin to VREG.

3.8 Charge Current Regulation Set (PROG1)

The maximum constant charge current is set by placinga resistor from PROG1 to VSS. PROG1 sets themaximum constant charge current for both ac-dcadapter and USB port. However, the actual chargecurrent is based on input source type and system loadrequirement.

3.9 USB-Port Current Regulation Set (PROG2)

The MCP73871 device USB-Port current regulation setinput (PROG2) is a digital input selection. A logic Lowselects a 1 unit load input current from USB port(100 mA); a logic High selects a 5 unit loads inputcurrent from USB port (500 mA).

3.10 Charge Status Output 1 (STAT1)STAT1 is an open-drain logic output for connection toan LED for charge status indication. Alternatively, apull-up resistor can be applied for interfacing to a hostmicrocontroller. Refer to Table 5-1 for a summary of thestatus output during a charge cycle.

3.11 Charge Status Output 2 (STAT2)STAT2 is an open-drain logic output for connection toan LED for charge status indication. Alternatively, apull-up resistor can be applied for interfacing to a hostmicrocontroller. Refer to Table 5-1 for a summary of thestatus output during a charge cycle.

3.12 Power-Good (PG)The power-good (PG) is an open-drain logic output forinput power supply indication. The PG output is lowwhenever the input to the MCP73871 device is abovethe UVLO threshold and greater than the batteryvoltage. The PG output can be used as an indication tothe user via an illuminated LED or to the system via apull-up resistor for interfacing to a host microcontrollerthat an input source other than the battery is supplyingpower. Refer to Table 5-1 for a summary of the statusoutput during a charge cycle.

3.13 Low Battery Output (LBO)STAT1 also serves as low battery output (LBO) if theselected MCP73871 is equipped with this feature. Itreminds the system or end user when the Li-Ion batteryvoltage level is low. The LBO feature enables when thesystem is running from the Li-Ion batteries. The LBOindicator can be used as an indication to the user via litup LED or to the system via a pull-up resistor forinterfacing to a host microcontroller that an inputsource other than the battery is supplying power. Referto Table 5-1 for a summary of the status output duringa charge cycle.

VVPCCR2

R1 R2+-------------------⎝ ⎠

⎛ ⎞ VIN 1.23V=×=

1.23V 110kΩ110kΩ R1+------------------------------⎝ ⎠

⎛ ⎞ 5V×=

R1 337.2kΩ=

330 kΩ

110 kΩ

VIN

VPCC


MCP73871
3.14 Timer Enable (TE)The timer enable (TE) feature is used to enable ordisable the internal timer. A low signal on this pinenables the internal timer and a high signal disablesthe internal timer. The TE input can be used to disablethe timer when the system load is substantially limitingthe available supply current to charge the battery. TheTE input is compatible with 1.8V logic.
3.15 Battery Temperature Monitor (THERM)

The MCP73871 device continuously monitor batterytemperature during a charge cycle by measuring thevoltage between the THERM and VSS pins. An internal50 µA current source provides the bias for mostcommon 10 kΩ negative-temperature coefficientthermistors (NTC). The MCP73871 device comparesthe voltage at the THERM pin to factory set thresholdsof 1.24V and 0.25V, typically. Once a voltage outsidethe thresholds is detected during a charge cycle, theMCP73871 device immediately suspends the chargecycle. The charge cycle resumes when the voltage atthe THERM pin returns to the normal range. Thecharge temperature window can be set by placing fixedvalue resistors in series-parallel with a thermistor.Refer to Section 6.0 “Applications” for calculationsof resistance values.

3.16 Charge Enable (CE)With the CE input Low, the Li-Ion battery chargerfeature of the MCP73871 will be disabled. The chargerfeature is enabled when CE is active High. Allowing theCE pin to float during the charge cycle may causesystem instability. The CE input is compatible with 1.8Vlogic. Refer to Section 6.0 “Applications” for variousapplications in designing with CE features.

3.17 Exposed Thermal Pad (EP)There is an internal electrical connection between theExposed Thermal Pad (EP) and the VSS pin; they mustbe connected to the same potential.

Note: The built-in safety timer is available for thefollowing options: 4 HR, 6 HR and 8 HR.


MCP73871
NOTES:

MCP73871

4.0 DEVICE OVERVIEWThe MCP73871 device is a simple, but fully integratedlinear charge management controllers with systemload sharing feature. Figure 4-1 depicts theoperational flow algorithm.

FIGURE 4-1: MCP73871 Device Flow Chart.

SHUTDOWN MODE * VDD < VUVLO VDD < VBAT

STAT1 = Hi-Z STAT2 = Hi-Z

PG = Hi-Z

PRECONDITIONING MODECharge Current = IPREG

STAT1 = LOW STAT2 = Hi-Z

PG = LOW Timer Reset

CONSTANT VOLTAGE MODE Charge Voltage = VREG

STAT1 = LOW

PG = LOW

VBAT > VPTH

CHARGE COMPLETE MODE No Charge Current

STAT1 = Hi-Z STAT2 = LOW

PG = LOW Timer Reset

IBAT < ITERMTimer Expired

VBAT < VPTH

STANDBY MODE * VBAT > (VREG +100 mV)

CE = LOW STAT1 = Hi-Z STAT2 = Hi-Z

PG = LOW

* Continuously Monitored

TEMPERATURE FAULT No Charge Current

STAT1 = LOW STAT2 = LOW

PG = LOW Timer Suspended

TIMER FAULT No Charge Current

STAT1 = LOW STAT2 = LOW

PG = LOW Timer Expired

LBO * VIN < VBAT


PG = Hi-Z

VBAT > VPTH

STAT2 = Hi-Z

Timer Reset

FAST CHARGE MODECharge Current = IREG


PG = LOW Timer Enabled


MCP73871
4.1 UnderVoltage Lockout (UVLO)An internal undervoltage lockout (UVLO) circuitmonitors the input voltage and keeps the charger inshutdown mode until the input supply rises above theUVLO threshold.
In the event a battery is present when the input poweris applied, the input supply must rise approximately100 mV above the battery voltage before theMCP73871 device become operational.

The UVLO circuit places the device in shutdown modeif the input supply falls to approximately 100 mV of thebattery voltage.

The UVLO circuit is always active. At any time, theinput supply is below the UVLO threshold orapproximately 100 mV of the voltage at the VBAT pin,the MCP73871 device is placed in a shutdown mode.

During any UVLO condition, the battery reversedischarge current shall be less than 2 µA.

4.2 System Load SharingThe system load sharing feature gives the systempriority on input power, allowing the system topower-up with deeply depleted battery packs.

With the SEL input active Low, the MCP73871 deviceis designed to provide system power and Li-Ion batterycharging from a USB input while adhering to the currentlimits governed by the USB specification.

With the SEL input active High, the MCP73871 devicelimits the total supply current to 1.8A (system powerand charge current combined).

FIGURE 4-2: System Load Sharing Diagram.

4.3 Charge QualificationFor a charge cycle to begin, all UVLO conditions mustbe met and a battery or output load must be present.

A charge current programming resistor must beconnected from PROG1 to VSS when SEL = High.When SEL = Low, PROG2 needs to tie to High or Lowfor proper operation.

4.4 PreconditioningIf the voltage at the VBAT pin is less than thepreconditioning threshold, the MCP73871 deviceenters a preconditioning mode. The preconditioningthreshold is factory set. Refer to Section 1.0“Electrical Characteristics” for preconditioningthreshold options.

In this mode, the MCP73871 device supplies 10% ofthe fast charge current (established with the value ofthe resistor connected to the PROG1 pin) to thebattery.

When the voltage at the VBAT pin rises above thepreconditioning threshold, the MCP73871 deviceenters the constant current (fast charge) mode.

4.5 Constant Current Mode - Fast Charge

During the constant current mode, the programmedcharge current is supplied to the battery or load. Thecharge current is established using a single resistorfrom PROG1 to VSS. The program resistor and thecharge current are calculated using the followingequation:

EQUATION 4-1:

Constant current mode is maintained until the voltageat the VBAT pin reaches the regulation voltage, VREG.

When constant current mode is invoked, the internaltimer is reset.

4.5.1 TIMER EXPIRED DURING CONSTANT CURRENT - FAST CHARGE MODE

If the internal timer expires before the recharge voltagethreshold is reached, a timer fault is indicated and thecharge cycle terminates. The MCP73871 deviceremains in this condition until the battery is removed. Ifthe battery is removed, the MCP73871 device entersthe Stand-by mode where it remains until a battery isreinserted.

4.6 Constant Voltage ModeWhen the voltage at the VBAT pin reaches theregulation voltage, VREG, constant voltage regulationbegins. The regulation voltage is factory set to 4.10Vor 4.20V with a tolerance of ±0.5%.

0.2ΩIdeal Diode, Synchronous Switch

DirectionControl

0.2Ω

CurrentLimit

DirectionControl

ChargeFET

System Power FET

VBAT

IN OUT

ChargeControl

IREG1000V

RPROG1--------------------=

Where:

RPROG = kilo-ohms (kΩ)

IREG = milliampere (mA)


MCP73871
4.7 Charge TerminationThe charge cycle is terminated when, during constantvoltage mode, the average charge current diminishesbelow a threshold established with the value of aresistor connected from PROG3 to VSS or internal timerhas expired. A 1 ms filter time on the terminationcomparator ensures that transient load conditions donot result in premature charge cycle termination. Thetimer period is factory set and can be disabled. Refer toSection 1.0 “Electrical Characteristics” for timerperiod options.
The program resistor and the charge current arecalculated using the following equation:

EQUATION 4-2:

The charge current is latched off and the MCP73871device enters a charge complete mode. Therecommended PROG3 resistor values are between5 kΩ and 100 kΩ.

4.8 Automatic RechargeThe MCP73871 device continuously monitors thevoltage at the VBAT pin in the charge complete mode. Ifthe voltage drops below the recharge threshold,another charge cycle begins and current is once againsupplied to the battery or load. The recharge thresholdis factory set. Refer to Section 1.0 “ElectricalCharacteristics” for recharge threshold options.

4.9 Thermal RegulationThe MCP73871 device limits the charge current basedon the die temperature. The thermal regulationoptimizes the charge cycle time while maintainingdevice reliability. Figure 4-3 depicts the thermalregulation for the MCP73871 device. Refer toSection 1.0 “Electrical Characteristics” for thermalpackage resistances and Section 6.1.1.2 “ThermalConsiderations” for calculating power dissipation..

FIGURE 4-3: Thermal Regulation

4.10 Thermal ShutdownThe MCP73871 device suspends charge if the dietemperature exceeds 150°C. Charging will resumewhen the die temperature has cooled by approximately10°C. The thermal shutdown is a secondary safetyfeature in the event that there is a failure within thethermal regulation circuitry.

4.11 Temperature QualificationThe MCP73871 device continuously monitor batterytemperature during a charge cycle by measuring thevoltage between the THERM and VSS pins. An internal50 µA current source provides the bias for mostcommon 10 kΩ negative-temperature coefficientthermistors (NTC). The MCP73871 device comparesthe voltage at the THERM pin to factory set thresholdsof 1.24V and 0.25V, typically. Once a voltage outsidethe thresholds is detected during a charge cycle, theMCP73871 device immediately suspends the chargecycle. The MCP73871 device suspends charge byturning off the charge pass transistor and holding thetimer value. The charge cycle resumes when thevoltage at the THERM pin returns to the normal range.

Note: Charge termination and automaticrecharge features avoid constant chargingLi-Ion batteries to prolong life of Li-Ionbatteries while keeping their capacity athealthy level.

ITERMINATION1000V

RPROG3--------------------=

Where:


IREG = milliampere (mA)0

200

400

600

800

1000

1200


Cha

rge

Cur

rent

(mA

)



MCP73871
4.12 Voltage Proportional Charge
Control (VPCC)If the voltage on the IN pin drops to a preset value,determined by the threshold established at the VPCCinput, due to a limited amount of input current or inputsource impedance, then the battery charging current isreduced. The VPCC control tries to reach asteady-state condition where the system load haspriority and the battery is charged with the remainingcurrent. Therefore, if the system demands morecurrent than the input can provide, the ideal diode willbecome forward biased and the battery is able tosupplement the input current to the system load.

The VPCC sustains the system load as its highestpriority. It does this by reducing the noncritical chargecurrent while maintaining the maximum power output ofthe adapter. Further demand from the system issupported by the battery, if possible.

The VPCC feature functions identically for USB port orac-dc adapter inputs. This feature can be disabled byconnecting the VPCC to IN pin.

4.13 Input Current Limit Control (ICLC)If the input current threshold is reached, then thebattery charging current is reduced. The ICLC tries toreach a steady-state condition where the system loadhas priority and the battery is charged with theremaining current. No active control limits the currentto the system. Therefore, if the system demands morecurrent than the input can provide or the input ICLC isreached, the ideal diode will become forward biasedand the battery is able to supplement the input currentto the system load.

The ICLC sustains the system load as its highestpriority. This is done by reducing the non-critical chargecurrent while adhering to the current limits governed bythe USB specification or the maximum ac-dc adaptercurrent supported. Further demand from the system issupported by the battery, if possible.

FIGURE 4-4: Input Current Limit Control - USB Port.

-200-100

0100200300400500600700

0 100 200 300 400 500 600 700

Load Current (mA)

Cur

rent

(mA

)Input CurrentBattery CurrentLoad Current

Ideal Diode


MCP73871

5.0 DETAILED DESCRIPTION

5.1 Analog Circuitry

5.1.1 LOAD SHARING AND LI-ION BATTERY MANAGEMENT INPUT SUPPLY (VIN)

The VIN input is the input supply to the MCP73871device. The MCP73871 device can be supplied byeither AC Adapter (VAC) or USB Port (VUSB) with SELpin. The MCP73871 device automatically powers thesystem with the Li-Ion battery when the VIN input is notpresent.

5.1.2 FAST CHARGE CURRENT REGULATION SET (PROG1)

For the MCP73871 device, the charge currentregulation can be scaled by placing a programmingresistor (RPROG1) from the PROG1 pin to VSS. Theprogram resistor and the charge current are calculatedusing the following equation:

EQUATION 5-1:

The fast charge current is set for maximum chargecurrent from ac-dc adapter and USB port. Thepreconditioning current is 10% (0.1C) to the fastcharge current.

5.1.3 BATTERY CHARGE CONTROL OUTPUT (VBAT)

The battery charge control output is the drain terminalof an internal P-channel MOSFET. The MCP73871device provides constant current and voltageregulation to the battery pack by controlling thisMOSFET in the linear region. The battery chargecontrol output should be connected to the positiveterminal of the battery pack.

5.1.4 TEMPERATURE QUALIFICATION (THERM)

The MCP73871 device continuously monitors batterytemperature during a charge cycle by measuring thevoltage between the THERM and VSS pins. An internal50 µA current source provides the bias for mostcommon 10 kΩ negative-temperature coefficient(NTC) or positive-temperature coefficient (PTC)thermistors.The current source is controlled, avoidingmeasurement sensitivity to fluctuations in the supplyvoltage (VDD). The MCP73871 device compares thevoltage at the THERM pin to factory set thresholds of

1.24V and 0.25V, typically. Once a voltage outside thethresholds is detected during a charge cycle, theMCP73871 device immediately suspends the chargecycle.

The MCP73871 device suspends charge by turning offthe pass transistor and holding the timer value. Thecharge cycle resumes when the voltage at the THERMpin returns to the normal range.

If temperature monitoring is not required, place astandard 10 kΩ resistor from THERM to VSS.

5.2 Digital Circuitry

5.2.1 STATUS INDICATORS AND POWER-GOOD (PG)

The charge status outputs have two different states:Low (L), and High Impedance (Hi-Z). The charge statusoutputs can be used to illuminate LEDs. Optionally, thecharge status outputs can be used as an interface to ahost microcontroller. Table 5-1 summarizes the state ofthe status outputs during a charge cycle.

TABLE 5-1: STATUS OUTPUTS

5.2.2 AC-DC ADAPTER AND USB PORT POWER SOURCE REGULATION SELECT (SEL)

With the SEL input Low, the MCP73871 device isdesigned to provide system power and Li-Ion batterycharging from a USB input while adhering to the currentlimits governed by the USB specification. The hostmicrocontroller has the option selecting either a100 mA (L) or a 500 mA (H) current limit based on thePROG2 input. With the SEL input High, the MCP73871device limits the input current to 1.8A. Theprogrammed charge current is established using asingle resistor from PROG1 to VSS when driving SELHigh.

IREG1000V

RPROG1--------------------=

Where:


IREG = milliampere (mA)

CHARGE CYCLE STATE STAT1 STAT2 PG

Shutdown (VDD = VBAT) Hi-Z Hi-Z Hi-ZShutdown (VDD = IN) Hi-Z Hi-Z LPreconditioning L Hi-Z LConstant Current L Hi-Z LConstant Voltage L Hi-Z LCharge Complete - Standby Hi-Z L LTemperature Fault L L LTimer Fault L L LLow Battery Output L Hi-Z Hi-ZNo Battery Present Hi-Z Hi-Z LNo Input Power Present Hi-Z Hi-Z Hi-Z


MCP73871
5.2.3 USB PORT CURRENT
REGULATION SELECT (PROG2)Driving the PROG2 input to a logic Low selects the lowUSB port source current setting (maximum 100 mA).Driving the PROG2 input to a logic High selects thehigh USB port source current setting (Maximum500 mA).

5.2.4 POWER-GOOD (PG)The power-good (PG) option is a pseudo open-drainoutput. The PG output can sink current, but not sourcecurrent. However, there is a diode path back to theinput, and as such, the output should only be pulled upto the input. The PG output is low whenever the inputto the MCP73871 device is above the UVLO thresholdand greater than the battery voltage. The PG outputcan be used as an indication to the system that an inputsource other than the battery is supplying power.

5.2.5 TIMER ENABLE (TE) OPTIONThe timer enable (TE) input option is used to enable ordisable the internal timer. A low signal on this pinenables the internal timer and a high signal disablesthe internal timer. The TE input can be used to disablethe timer when the charger is supplying current tocharge the battery and power the system load. The TEinput is compatible with 1.8V logic.


MCP73871

6.0 APPLICATIONSThe MCP73871 device is designed to operate inconjunction with a host microcontroller or instand-alone applications. The MCP73871 deviceprovides the preferred charge algorithm for Lithium-Ion

and Lithium-Polymer cells Constant-current followedby Constant-voltage. Figure 6-1 depicts a typicalstand-alone MCP73871 application circuit, whileFigures 6-2 and 6-3 depict the accompanying chargeprofile.

FIGURE 6-1: MCP73871Typical Stand-Alone Application Circuit with VPCC.

FIGURE 6-2: Typical Charge Profile (1000 mAh Battery).

FIGURE 6-3: Typical Charge Profile in Preconditioning (1000 mAh Battery).

STAT1 LBO

IN OUT

PG VBAT

Single-Cell Li-Ion Battery

7

MCP73871 Device Typical Application

1, 20

8

18, 19

10 µF

10, 11, EP

5V AC-DC Adapter or

USB Port

STAT2

THERM

VSS

PROG1

PROG3 12

13 RPROG1

6

5

14, 15, 16

470Ω

470Ω

470Ω

2

4.7 µF

System Load

SEL

TE

PROG2

HiLow

HiLow

HiLow

3

4

9

RPROG3

VPCC

NTC

10 kΩ

HiLow17

CE

4.7 µF

330 kΩ

110 kΩ

00.5

11.5

22.5

33.5

44.5

0 10 20 30 40 50 60 70 80

Time (Minute)

Cha

rge

Vol

tage

(V)

00.20.40.60.811.21.41.61.82

Cha

rge

Cur

rent

(A)


00.5

11.5

22.5

33.5

44.5

0 0.2 0.4 0.6 0.8 1Time (Minute)

Cha

rge

Vol

tage

(V)

00.20.40.60.811.21.41.61.82

Cha

rge

Cur

rent

(A)

Preconditioning

Preconditioning Threshold Voltage

Fast Charge (Constant Current)



MCP73871
6.1 Application Circuit Design Due to the low efficiency of linear charging, the mostimportant factors are thermal design and cost, whichare a direct function of the input voltage, output currentand thermal impedance between the battery chargerand the ambient cooling air. The worst-case situation iswhen the device has transitioned from thePreconditioning mode to the Constant Current mode. Inthis situation, the battery charger has to dissipate themaximum power. A trade-off must be made betweenthe charge current, cost and thermal requirements ofthe charger.
6.1.1 COMPONENT SELECTIONSelection of the external components in Figure 6-1 iscrucial to the integrity and reliability of the chargingsystem. The following discussion is intended as a guidefor the component selection process.

6.1.1.1 Charge Current The preferred fast charge current for Lithium-Ion cellsshould always follow references and guidances frombattery manufacturers. For example, a 1000 mAhbattery pack has a preferred fast charge current of0.7C. Charging at 700 mA provides the shortest chargecycle times without degradation to the battery packperformance or life.

6.1.1.2 Thermal ConsiderationsThe worst-case power dissipation in the batterycharger occurs when the input voltage is at themaximum and the device has transitioned from thePreconditioning mode to the Constant-current mode. Inthis case, the power dissipation is:

EQUATION 6-1:

For example, power dissipation with a 5V, ±10% inputvoltage source and 500 mA, ±10% fast charge currentis:

EXAMPLE 6-1:

This power dissipation with the battery charger in theQFN-20 package will cause thermal regulation to beentered as depicted. Alternatively, the 4 mm x 4 mmDFN package could be utilized to reduce heat byadding vias on the exposed pad.

6.1.1.3 External CapacitorsThe MCP73871 device is stable with or without abattery load. In order to maintain good AC stability inthe Constant Voltage mode, a minimum capacitance of4.7 µF is recommended to bypass the VBAT pin to VSS.This capacitance provides compensation when there isno battery load. In addition, the battery andinterconnections appear inductive at high frequencies.These elements are in the control feedback loop duringConstant Voltage mode. Therefore, the bypasscapacitance may be necessary to compensate for theinductive nature of the battery pack.

Virtually any good quality output filter capacitor can beused, independent of the capacitor’s minimumEffective Series Resistance (ESR) value. The actualvalue of the capacitor (and its associated ESR)depends on the output load current. A 4.7 µF ceramic,tantalum or aluminum electrolytic capacitor at theoutput is usually sufficient to ensure stability for chargecurrents up to a 1000 mA.

6.1.1.4 Reverse-Blocking ProtectionThe MCP73871 device provides protection from afaulted or shorted input. Without the protection, afaulted or shorted input would discharge the batterypack through the body diode of the internal passtransistor.

6.1.1.5 Temperature MonitoringThe charge temperature window can be set by placingfixed value resistors in series-parallel with a thermistor.The resistance values of RT1 and RT2 can be calculatedwith the following equations in order to set thetemperature window of interest.

For NTC thermistors:

EQUATION 6-2:

PowerDissipation VDDMAX VPTHMIN–( ) IREGMAX×=

Where:

VDDMAX = the maximum input voltageIREGMAX = the maximum fast charge currentVPTHMIN = the minimum transition threshold

voltage

PowerDissipation 5.5V 2.7V–( ) 550mA× 1.54W= =

24kΩ RT1RT2 RCOLD×RT2 R+ COLD---------------------------------+=

5kΩ RT1RT2 RHOT×RT2 R+ HOT-----------------------------+=

Where:

RT1 = the fixed series resistanceRT2 = the fixed parallel resistance

RCOLD = the thermistor resistance at the lower temperature of interest

RHOT = the thermistor resistance at the upper temperature of interest


MCP73871
For example, by utilizing a 10 kΩ at 25°C NTCthermistor with a sensitivity index, β, of 3892, thecharge temperature range can be set to 0°C - 50°C byplacing a 1.54 kΩ resistor in series (RT1), and a69.8 kΩ resistor in parallel (RT2) with the thermistor.
6.1.1.6 Charge Status InterfaceA status output provides information on the state ofcharge. The output can be used to illuminate externalLEDs or interface to a host microcontroller. Refer toTable 5-1 for a summary of the state of the statusoutput during a charge cycle.

6.1.1.7 System Load CurrentThe preferred discharge current for Lithium-Ion cellsshould always follow references and guidance frombattery manufacturers. Due to the safety concernswhen using Lithium-Ion batteries and powerdissipation of linear solutions, the system load whendesign with the MCP73871 device is recommended tobe less than 1A or the maximum discharge rate of theselected Lithium-Ion cell. Whichever is smaller isrecommended.

The idea diode between VBAT and OUT is designed todrive a maximum current up to 2A. The built-in thermalshutdown protection may turn the MCP73871 deviceoff with high current.

6.2 PCB Layout IssuesFor optimum voltage regulation, place the battery packas close as possible to the device’s VBAT and VSS pins,recommended to minimize voltage drops along thehigh current-carrying PCB traces.

If the PCB layout is used as a heatsink, adding manyvias in the heatsink pad can help conduct more heat tothe backplane of the PCB, thus reducing the maximumjunction temperature.


MCP73871
NOTES:

MCP73871

7.0 PACKAGING

7.1 Package Marking Information

20-Lead QFN Example:

XXXXXXXXXXXX

YWWNNN

Part Number * MarkingCode Part Number * Marking

CodeMCP73871-1AAI/ML 1AA MCP73871T-1AAI/ML 1AAMCP73871-1CAI/ML 1CA MCP73871T-1CAI/ML 1CAMCP73871-1CCI/ML 1CC MCP73871T-1CCI/ML 1CCMCP73871-2AAI/ML 2AA MCP73871T-2AAI/ML 2AAMCP73871-2CAI/ML 2CA MCP73871T-2CAI/ML 2CAMCP73871-2CCI/ML 2CC MCP73871T-2CCI/ML 2CCMCP73871-3CAI/ML 3CA MCP73871T-3CAI/ML 3CAMCP73871-3CCI/ML 3CC MCP73871T-3CCI/ML 3CCMCP73871-4CAI/ML 4CA MCP73871T-4CAI/ML 4CAMCP73871-4CCI/ML 4CC MCP73871T-4CCI/ML 4CC* Consult Factory for Alternative Device Options.

Legend: XX...X Customer-specific informationY Year code (last digit of calendar year)YY Year code (last 2 digits of calendar year)WW Week code (week of January 1 is week ‘01’)NNN Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn)* This package is Pb-free. The Pb-free JEDEC designator ( )

can be found on the outer packaging for this package.

Note: In the event the full Microchip part number cannot be marked on one line, it willbe carried over to the next line, thus limiting the number of availablecharacters for customer-specific information.

3e

3e

XXXXX1AA

I/ML^^919256

73871

3e


MCP73871

!"#$

% !"#$%!&'(!%&! %(%")%%%" * ) !%"+ & "%,-.

/01 / & %#%! ))%!%% ,21 $& '! !)%!%%'$$&%!

% 2%& %!%*") ' %*$%%"%%%133)))&&3*

4% 55, ,& 5&% 6 67 8

6!&($ 6 % ./079% : %"$$ .0%% * + ,27;"% , /0,# "";"% , < :75% /0,# ""5% < :0%%;"% ( : . +0%%5% 5 + .0%%%,# "" = > >

DEXPOSED

PAD

E

E2

2

1

N

TOP VIEW NOTE 1

N

L

K

b

e

D2

2

1

A

A1A3

BOTTOM VIEW

) 0</


MCP73871

% 2%& %!%*") ' %*$%%"%%%133)))&&3*


MCP73871
NOTES:

MCP73871

APPENDIX A: REVISION HISTORY

Revision B (May 2009)The following is the list of modifications:

1. Updated the QFN-20 package drawing.2. Updated Equation 4-1.3. Updated Section 4.7 “Charge Termination”

and Equation 4-2.4. Updated Equation 5-1.

Revision A (July 2008)• Original Release of this Document.


MCP73871
NOTES:

MCP73871

PRODUCT IDENTIFICATION SYSTEMTo order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

* Operational Output Options

Device: MCP73871: USB/AC Battery Charger with PPM

MCP73871T: USB/AC Battery Charger with PPM(Tape and Reel)

Output Options * * * Refer to table below for different operational options.

* * Consult Factory for Alternative Device Options.

Temperature: I = -40°C to +85°C

Package Type: ML = Plastic Quad Flat No Lead (QFN)(4x4x0.9 mm Body), 20-lead

PART NO. XX

OutputDeviceOptions*

X/

Temp.

XX

Package

Examples: * *a) MCP73871-1AAI/ML: 4.10V PPM Battery

Charger, 20LD QFNpkg.

b) MCP73871-1CAI/ML: 4.10V, PPM BatteryCharger, 20LD QFNpkg.

c) MCP73871-1CCI/ML: 4.10V, PPM BatteryCharger, 20LD QFNpkg.

d) MCP73871-2AAI/ML: 4.20V, PPM BatteryCharger, 20LD QFNpkg.

e) MCP73871-2CAI/ML: 4.20V PPM BatteryCharger, 20LD QFNpkg.

f) MCP73871-2CCI/ML: 4.20V PPM BatteryCharger, 20LD QFNpkg.

g) MCP73871-3CAI/ML: 4.35V PPM BatteryCharger, 20LD QFNpkg.

h) MCP73871-3CCI/ML: 4.35V PPM BatteryCharger, 20LD QFNpkg.

* * Consult Factory for Alternative Device Options

OutputOptions VREG

Safety TimerDuration (Hours)

LBO VoltageThreshold (V)

1AA 4.10V Disable Disabled1CA 4.10V 6 Disabled1CC 4.10V 6 3.12AA 4.20V Disable Disabled2CA 4.20V 6 Disabled2CC 4.20V 6 3.13CA 4.35V 6 Disabled3CC 4.35V 6 3.14CA 4.40V 6 Disabled4CC 4.40V 6 3.1

* * Consult Factory for Alternative Device Options.


MCP73871
NOTES:

Note the following details of the code protection feature on Microchip devices:• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of ourproducts. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such actsallow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding deviceapplications and the like is provided only for your convenienceand may be superseded by updates. It is your responsibility toensure that your application meets with your specifications.MICROCHIP MAKES NO REPRESENTATIONS ORWARRANTIES OF ANY KIND WHETHER EXPRESS ORIMPLIED, WRITTEN OR ORAL, STATUTORY OROTHERWISE, RELATED TO THE INFORMATION,INCLUDING BUT NOT LIMITED TO ITS CONDITION,QUALITY, PERFORMANCE, MERCHANTABILITY ORFITNESS FOR PURPOSE. Microchip disclaims all liabilityarising from this information and its use. Use of Microchipdevices in life support and/or safety applications is entirely atthe buyer’s risk, and the buyer agrees to defend, indemnify andhold harmless Microchip from any and all damages, claims,suits, or expenses resulting from such use. No licenses areconveyed, implicitly or otherwise, under any Microchipintellectual property rights.

© 2009 Microchip Technology Inc.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC, SmartShunt and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

FilterLab, Hampshire, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, nanoWatt XLP, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.

All other trademarks mentioned herein are property of their respective companies.

© 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.

Printed on recycled paper.

DS22090B-page 37

Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified.


AMERICASCorporate Office2355 West Chandler Blvd.Chandler, AZ 85224-6199Tel: 480-792-7200 Fax: 480-792-7277Technical Support: http://support.microchip.comWeb Address: www.microchip.comAtlantaDuluth, GA Tel: 678-957-9614 Fax: 678-957-1455BostonWestborough, MA Tel: 774-760-0087 Fax: 774-760-0088ChicagoItasca, IL Tel: 630-285-0071 Fax: 630-285-0075ClevelandIndependence, OH Tel: 216-447-0464 Fax: 216-447-0643DallasAddison, TX Tel: 972-818-7423 Fax: 972-818-2924DetroitFarmington Hills, MI Tel: 248-538-2250Fax: 248-538-2260KokomoKokomo, IN Tel: 765-864-8360Fax: 765-864-8387Los AngelesMission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608Santa ClaraSanta Clara, CA Tel: 408-961-6444Fax: 408-961-6445TorontoMississauga, Ontario, CanadaTel: 905-673-0699 Fax: 905-673-6509

ASIA/PACIFICAsia Pacific OfficeSuites 3707-14, 37th FloorTower 6, The GatewayHarbour City, KowloonHong KongTel: 852-2401-1200Fax: 852-2401-3431Australia - SydneyTel: 61-2-9868-6733Fax: 61-2-9868-6755China - BeijingTel: 86-10-8528-2100 Fax: 86-10-8528-2104China - ChengduTel: 86-28-8665-5511Fax: 86-28-8665-7889China - Hong Kong SARTel: 852-2401-1200 Fax: 852-2401-3431China - NanjingTel: 86-25-8473-2460Fax: 86-25-8473-2470China - QingdaoTel: 86-532-8502-7355Fax: 86-532-8502-7205China - ShanghaiTel: 86-21-5407-5533 Fax: 86-21-5407-5066China - ShenyangTel: 86-24-2334-2829Fax: 86-24-2334-2393China - ShenzhenTel: 86-755-8203-2660 Fax: 86-755-8203-1760China - WuhanTel: 86-27-5980-5300Fax: 86-27-5980-5118China - XiamenTel: 86-592-2388138 Fax: 86-592-2388130China - XianTel: 86-29-8833-7252Fax: 86-29-8833-7256China - ZhuhaiTel: 86-756-3210040 Fax: 86-756-3210049

ASIA/PACIFICIndia - BangaloreTel: 91-80-3090-4444 Fax: 91-80-3090-4080India - New DelhiTel: 91-11-4160-8631Fax: 91-11-4160-8632India - PuneTel: 91-20-2566-1512Fax: 91-20-2566-1513Japan - YokohamaTel: 81-45-471- 6166 Fax: 81-45-471-6122Korea - DaeguTel: 82-53-744-4301Fax: 82-53-744-4302Korea - SeoulTel: 82-2-554-7200Fax: 82-2-558-5932 or 82-2-558-5934Malaysia - Kuala LumpurTel: 60-3-6201-9857Fax: 60-3-6201-9859Malaysia - PenangTel: 60-4-227-8870Fax: 60-4-227-4068Philippines - ManilaTel: 63-2-634-9065Fax: 63-2-634-9069SingaporeTel: 65-6334-8870Fax: 65-6334-8850Taiwan - Hsin ChuTel: 886-3-6578-300Fax: 886-3-6578-370Taiwan - KaohsiungTel: 886-7-536-4818Fax: 886-7-536-4803Taiwan - TaipeiTel: 886-2-2500-6610 Fax: 886-2-2508-0102Thailand - BangkokTel: 66-2-694-1351Fax: 66-2-694-1350

EUROPEAustria - WelsTel: 43-7242-2244-39Fax: 43-7242-2244-393Denmark - CopenhagenTel: 45-4450-2828 Fax: 45-4485-2829France - ParisTel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79Germany - MunichTel: 49-89-627-144-0 Fax: 49-89-627-144-44Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781Netherlands - DrunenTel: 31-416-690399 Fax: 31-416-690340Spain - MadridTel: 34-91-708-08-90Fax: 34-91-708-08-91UK - WokinghamTel: 44-118-921-5869Fax: 44-118-921-5820

WORLDWIDE SALES AND SERVICE

03/26/09

mcp73871 cargador

Documents