Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

An innovative PWM loop An innovative PWM loop control control

for VRMsfor VRMsD.I.E.E.T. – Università di PalermoD.I.E.E.T. – Università di Palermo

Ing. Giuseppe Maria DI BLASI

Ing. Valeria BOSCAINO

Ing. Patrizia LIVRERI

Prof. Ing. Giuseppe CAPPONI

I&PC Division – STMicroelectronicsI&PC Division – STMicroelectronics

Ing. Filippo MARINO

Ing. Marco MINIERI

Power Applications LabPower Applications LabDIEET i&p

industrial & power conversion

division

http://www.dieet.unipa.it/labepdiblasi@diepa.unipa.itdiblasi@diepa.unipa.it

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

OutlineOutline

IntroductionIntroduction

Innovative current-sensingInnovative current-sensing

Two-module interleaved buck converterTwo-module interleaved buck converter

Prototype experimental resultsPrototype experimental results

ConclusionConclusion

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Future generations of microprocessors: Supply Voltage < 1V

Supply Current > 100A

Faster transient slew rate (100A/s)

Introduction Introduction (1)(1)

Increasing speed data processing

Decreasing power consumption

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Introduction Introduction (2)(2)

Large amount of output filter and on-board

decoupling capacitors

Low efficiency

Large ripple of steady-state output signal

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Introduction Introduction (3)(3)

Multi-module interleaved buck converter

Low occupied space

Low cost Current-sharing control

The most important function on VRM applications is current sensingcurrent sensing

Good steady-state and transient performances

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Vea

Low side

Power phase node

+

Vout

-

High side

+Vsense- Vref

250kHz

Clock

DRIVER

EA

S

RQ_Q

C

+ Vdc

Cs

L

R

ESR

Rs

RL

R2

C2

Current-voltage (IV) control loop

Innovative current-sensing Innovative current-sensing (1)(1)

Innovative sense to generate saw-tooth

Patent pendingInnovative

IV loop

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Current-voltage (IV) control loop

Innovative current-sensing Innovative current-sensing (2)(2)

Current-mode topology

Simple current-sensing and current-sharing implementation

No dissipative elements introduced

No limitations of traditional current-mode control

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Two-module interleaved buck Two-module interleaved buck converterconverter

Input voltage: Vdc = 12V

Output voltage: Vo = 1V

Switching frequency: fs = 250kHz

Output current: Io = 1÷60A

Output current slew-rate: S.R. = 60 A/μs

Maximum dynamic output voltage ripple: ∆Vo≤ 30mV

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Prototype experimental results Prototype experimental results (1)(1)

Sensing signal at 1A load

Saw-tooth 03.6V

Saw-tooth signal has the same waveform

of inductor current

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Prototype experimental results Prototype experimental results (2)(2)

Sensing signal at 20A load

Saw-tooth 04V

Saw-tooth signal has the same waveform

of inductor current

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Prototype experimental results Prototype experimental results (3)(3)

IOUT=30A

Adaptive VoltagePositioning

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

Prototype experimental results Prototype experimental results (4)(4)

IOUT=30A

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

ConclusionConclusion

New current-sensing technique is proposed

New current-mode control is implemented

Experimental results on two-module buck

converter are excellent