MP2932 - 6-PHASE PWM CONTROLLER WITH 8-BIT ADC CODE
MP2932 Rev.1.02 www.MonolithicPower.com 10
4/30/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
OPERATION
Multiphase Power Conversion
The MP2932 is a multiphase VR controller for
Intel VR11 or VR10. It can be programmed for 2-,
3-, 4-, 5- or 6 channel operation for micro-
processor core supply power converters with
interleaved switching. The interleaving work of
each phase can help to reduce of ripple current
amplitude in the multiphase circuit and to reduce
input ripple current.
The MP2932 control system is based on Dual-
Edge PWM providing the fastest load response.
Under load transition condition, the MP2932 can
turn on all phase together to improve the load
transient. It can achieve excellent transient
performance and reduce the demand on the
output capacitors.
Number of Phases
The number of operational phases is determined
by internal circuitry that monitors the PWM
outputs. Normally, the MP2932 operates as a 6-
phase controller. The number of active channels
is determined by the state of PWM3, PWM4,
PWM5, and PWM6. For 2-phase operation,
connect PWM3 to VCC; similarly, PWM4 for 3-
phase, PWM5 for 4-phase, and PWM6 for 5-
phase operation. Table 1 shows the phase firing
sequence.
Table 1—Phase firing sequence
Configuration Phase Sequence
6-Phase 1 - 2 - 3 - 4 - 5 - 6
5-Phase 1 - 2 - 3 - 4 - 5
4-Phase 1 - 3 - 4 - 2
3-Phase 1 - 2 - 3
2-Phase 1 - 2
Switching Frequency
The clock frequency is set by an external resistor
R
T
connected from the FS pin to GND.
The resistor R
T
can be estimated by Equation (1).
600
SW
10
T
F
102.5
R
(1)
Where F
SW
is the switching frequency of each
phase.
Current Sensing
MP2932 has cycle by cycle current sense for fast
response. MP2932 adopts inductor DCR sensing,
or resistive sensing techniques. The sense
current, I
SEN
, is proportional to the inductor
current. The sensed current is used for current
balance, load-line regulation, and overcurrent
protection.
Inductor DCR Sensing
The MP2932 can adopt a lossless current
sensing scheme, commonly referred to as
inductor DCR sensing, as shown in Figure 2.
CURRENT
SENSE
ISEN+(n)
ISEN-(n)
RC
V (s)
V
LDCR
MP2932 INTERNAL CIRCUIT
SW
PWM
Intelli-Phase
Vin
Vin
GND
PWM(n)
I(s)
C
V
OUT
C
OUT
R
ISEN(n)
L
L
=I
R
DCR
SEN
I
L
ISEN
I
n
C
T
Figure 2—DCR Sensing Configuration
Equation (2) shows the s-domain equivalent
voltage across the inductor V
L
.
DCRLs
L
I
L
V
(2)
A simple RC network across the inductor extracts
the DCR voltage, as shown in Figure 2.
The voltage on the capacitor V
C
, can be shown to
be proportional to the channel current I
L
, see
Equation (3).
1RCs
L
IDCR1
DCR
L
s
C
V
(3)
