Rainbow Electronics MAX8775 - Manual (Page 12)

MAX8775
Detailed Description
The MAX8775 is a dual fixed-frequency step-down con-
troller for low-voltage I/O and graphics core (GPU) sup-
plies. It can be configured as two separate regulators
generating two independent outputs. Alternatively, the
MAX8775 can be configured in combined mode as a
two-phase, single-output, high-current regulator, pow-
ering the high-performance graphics cores used in
game machines and media center notebooks.
The standard applications circuit (Figure 1) generates
dynamically adjustable output voltages on both out-
puts. REFIN voltage setting allows for multiple dynamic
Dual and Combinable Graphics Core
Controller for Notebook Computers
12 ______________________________________________________________________________________
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
0.88 μH
D L1
C IN1
N H1
N L1
V OUT1
1.5V/1.2V 15A
CSL2
CSH2
LX2
DH2
BST2
DL2
ANALOG GROUND
POWER GROUND
R SENSE1
1.5m Ω
R10
150 Ω
R11
10 Ω
C1
2.2nF
C2
4.7nF
R1
100k Ω
OVP1
REFIN1
REF
V OUT1(L)
V OUT2(L)
V OUT1(H)
V OUT2(H)
SEE TABLE 1 FOR COMPONENT
SPECIFICATIONS.
R3
249k Ω
R2
150k Ω
OVP2
REFIN2
REF
R9
100k
Ω
C OUT1
(2) 330 μF
PGND
MAX8775
C
SLEW1
470pF
C SLEW2
470pF
R4
100k Ω
R6
249k Ω
R5
150k Ω
C BST2
0.1 μF
INPUT V IN
7V TO 20V
L2
0.88 μH
D
L2
C IN2
N H2
N L2
V OUT2
1.5V/1.2V 15A
R SENSE2
1.5m Ω
R12
150 Ω
R13
10 Ω
C5
2.2nF
C6
4.7nF
C OUT2
(2) 330 μF
EP
Figure 1. MAX8775 Separate Output Typical Operating Circuit