Power Applications Lab
i&pdivision
DIEET
industrial & power conversion
An innovative PWM loop control
for VRMs
D.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 – STMicroelectronics
Ing. Filippo MARINO
Ing. Marco MINIERI
http://www.dieet.unipa.it/labep
[email protected]
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Outline

Introduction

Innovative current-sensing

Two-module interleaved buck converter

Prototype experimental results

Conclusion
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Introduction (1)

Future generations of microprocessors:
 Supply Voltage < 1V
 Supply Current > 100A
 Faster transient slew rate (100A/s)
Increasing
speed data processing
Riunione Annuale GE 2006
Decreasing
power consumption
Ischia, 21-23 giugno 2006
Introduction (2)
Low efficiency
Large ripple
of steady-state
output signal
Large amount
of output filter and on-board
decoupling capacitors
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Introduction (3)
Multi-module interleaved buck converter
Low occupied space
Low cost
Current-sharing
control
Good steady-state and
transient performances
The most important function on VRM
applications is current sensing
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Innovative current-sensing (1)
Current-voltage (IV) control loop
High side
+ Vdc
Power phase node
L
RL
Innovative sense to
generate saw-tooth
Low side
+
ESR
R Vout
DRIVER
C
-
R
Rs2
Q
_
Q
S
R
Clock
CCs
2
250kHz
Riunione Annuale GE 2006
+
Vsense
Vea
Patent pending
Vref
Innovative
IV loop
EA
Ischia, 21-23 giugno 2006
Innovative current-sensing (2)
Current-voltage (IV) control loop
Current-mode topology
Simple current-sensing and
current-sharing implementation
No dissipative elements introduced
No limitations of traditional
current-mode control
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Two-module interleaved buck converter

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
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Prototype experimental results (1)
Sensing signal
at 1A load
Saw-tooth 03.6V
Saw-tooth signal
has the same waveform
of inductor current
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Prototype experimental results (2)
Sensing signal
at 20A load
Saw-tooth 04V
Saw-tooth signal
has the same waveform
of inductor current
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Prototype experimental results (3)
IOUT=30A
Adaptive Voltage
Positioning
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Prototype experimental results (4)
IOUT=30A
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Conclusion

New current-sensing technique is proposed

New current-mode control is implemented

Experimental results on two-module buck
converter are excellent
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006