Rainbow Electronics MAX8775 - Manual (Page 13)

output voltages required by the different GPU operating
and sleep states. Automatic fault blanking, forced-PWM
operation, and transition control are achieved by
detecting the voltage change at REFIN.
The interleaved, fixed-frequency architecture provides
180° out-of-phase operation to reduce the input capaci-
tance required to meet the RMS input-current ratings.
Each controller consists of a multi-input PWM compara-
tor, high-side and low-side gate drivers, fault protec-
tion, power-good detection, soft-start, and shutdown
logic. Current-mode control allows the use of low-ESR
output capacitors.
In combined mode (Figure 2), phase 1 provides the
main voltage-control loop while phase 2 maintains the
MAX8775
Dual and Combinable Graphics Core
Controller for Notebook Computers
______________________________________________________________________________________ 13
V
DD
V
CC
C4
1 μF
OSC
R OSC
154k Ω
CCI2
REF
R7
10 Ω
PGOOD1
+5V
R8
100k Ω
PGOOD2
GND
SKIP1
SKIP2
ON1
ON2
SLEW1
C REF
0.1 μF
SLEW2
NOT USED
DTRANS
C BST1
0.1 μF
+5V
LX1
DH1
BST1
DL1
CSL1
CSH1
C3
2.2
μF
INPUT V IN
7V TO 20V
L1
0.56 μH
D L1
C IN1
N H1
N L1
V OUT
1.5V/1.2V 40A
CSL2
CSH2
LX2
DH2
BST2
DL2
ANALOG GROUND
POWER GROUND
R
SENSE1
1.0m Ω
R10
100 Ω
R11
10 Ω
C1
2.2nF
C2
4.7nF
R1
100k Ω
OVP1
REFIN1
REF
REF
V CC
V OUT(L) V OUT(H)
CONNECT REFIN2 TO V CC AND
OVP2 TO REF OR V CC FOR
COMBINED-MODE OPERATION
SEE TABLE 1 FOR COMPONENT
SPECIFICATIONS.
R3
249k Ω
R2
150k Ω
OVP2
REFIN2
R9
100k
Ω
C OUT
(4) 330 μF
PGND
MAX8775
C SLEW
1000pF
C BST2
0.1 μF
INPUT V IN
7V TO 20V
L2
0.56 μH
D L2
C IN2
N
H2
N L2
R SENSE2
1.0m Ω
R12
100 Ω
R13
10 Ω
C5
2.2nF
C6
4.7nF
C
CCI2
47pF
EP
Figure 2. MAX8775 Combined-Output Typical Operating Circuit