Rainbow Electronics MAX8775 - Manual

General Description
The MAX8775 is a dual, step-down, interleaved, fixed-
frequency, switch-mode power-supply (SMPS) con-
troller with synchronous rectification. It is intended for
GPU cores and I/O power generation in battery-pow-
ered systems. Flexible configuration allows the
MAX8775 to operate as two independent single-phase
regulators, or as one high-current two-phase regulator.
Configured in separate mode, the MAX8775 provides
power to two dynamic voltage rails, one for the GPU
core and the other for the I/O power rail. Configured in
combined mode, the MAX8775 functions as a two-
phase, high-current, single-output GPU core regulator,
powering the high-performance GPU engines used in
gaming machines and media center notebooks.
The REFIN voltage setting allows for multiple dynamic
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. Fixed-frequen-
cy operation with 180° out-of-phase interleaving mini-
mizes input ripple current from the lowest input
voltages up to the 26V maximum input. Current-mode
control allows the use of low-ESR output capacitors.
Internal integrators maintain high output accuracy over
the full line-and-load range, in both forced-PWM mode
and pulse-skipping mode. True differential current
sensing provides accurate output current limit and cur-
rent balance when operated in combined mode.
Independent on/off and skip control allows flexible
power sequencing and power management. Voltage-
controlled soft-start reduces inrush current. Soft-stop
gradually ramps the output voltage down, preventing
negative voltage dips.
Applications
2 to 4 Li+ Cells Battery-Powered Devices
Media Center and Gaming Notebooks
GPU and I/O Power Supplies
Tracking Output Power Supplies
Features
♦ Dual-Output, Fixed-Frequency, Current-Mode
Control
♦ Combinable Output for Higher Currents
♦ Dynamic Output Voltages with Automatic Fault
Blanking and Transition Control
♦ True Out-of-Phase Operation
♦ True Differential Current Sense for Accurate
Current Limit and Current Balance
♦ 4V to 26V Input Range
♦ 100kHz to 600kHz Switching Frequency
♦ 0.5V to 2.5V Adjustable Outputs
♦ Internal Integrator for High Output Accuracy
♦ Stable with Low-ESR Output Capacitors
♦ Independent Selectable PWM and Skip-Mode
Operation
♦ Independent Power-Good Outputs
♦ Soft-Start and Soft-Stop
♦ 2.5V Precision Reference
♦ < 1µA Typical Shutdown Current
MAX8775
Dual and Combinable Graphics Core
Controller for Notebook Computers
________________________________________________________________ Maxim Integrated Products 1
MAX8775
THIN QFN
5mm x 5mm
TOP VIEW
29
30
28
27
12
11
13
OSC V
CC
AGND
REF
REFIN2
14
OVP1
LX1 V
DD
PGND BST1 DL2 LX2
1 2
CSH1
4 5 6 7
23 24 22 20 19 18
SKIP1
PGOOD1
CSL2
CSH2
PGOOD2
REFIN1
DL1
3
21
31 10 DTRANS CCI2
32 9 SLEW1 SLEW2
CSL1
26 15 ON2 ON1
25 16 DH2
OVP2
BST2
8
17
DH1
SKIP2
Pin Configuration
Ordering Information
19-0670; Rev 0; 11/06
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE
PIN-
PACKAGE PKG
CODE
MAX8775ETJ+ -40°C to +85°C
32 Thin QFN
5mm x 5mm
T3255-5
+ Denotes lead-free package.