MAX8707 Datasheet, PDF (1/37 Pages) Maxim Integrated Products – Multiphase, Fixed-Frequency Controller for AMD Hammer CPU Core Power Supplies

19-3360; Rev 0; 8/04
Multiphase, Fixed-Frequency Controller for
AMD Hammer CPU Core Power Supplies
General Description
The MAX8707 is a multiphase (3-/4-phase), interleaved,
fixed-frequency, step-down controller for AMD Hammer
CPU core supplies. Interleaved multiphase operation
reduces the input ripple current and output voltage ripple
while easing component selection and layout placement.
The MAX8707 includes active voltage positioning with
adjustable gain and offset, reducing power dissipation
and bulk output-capacitance requirements.
The MAX8707 is intended for two different notebook
CPU core applications: stepping down the battery
directly or stepping down the +5V system supply to
create the core voltage. The single-stage conversion
method allows these devices to directly step down
high-voltage batteries for the highest possible efficien-
cy. Alternatively, 2-stage conversion (stepping down
the +5V system supply instead of the battery) at higher
switching frequency provides the minimum possible
physical size.
The MAX8707 features dedicated differential current-
sense inputs for each phase and includes a fifth pair of
current-sense inputs to provide an accurate voltage-
positioning slope and average current-limit protection
using a single current-sense resistor. The MAX8707 also
has two dedicated inputs that provide differential remote
voltage sensing.
The MAX8707 provides an analog input for setting the
suspend voltage and a slew-rate controller for transi-
tions between VID codes or the suspend voltage. The
controllers reduce the transition slew rate during startup
and shutdown, providing soft-start with minimal input
surge current and damped soft-shutdown without nega-
tive output undershoot. The MAX8707 includes output
fault protection—undervoltage, nonlatched overvoltage,
and thermal overload—and an independent voltage-
regulator power-OK (VROK) output.
The MAX8707 has a selectable switching frequency,
allowing 200kHz, 300kHz, or 600kHz per-phase opera-
tion. The MAX8707 is available in the low-profile, 40-pin,
6mm x 6mm thin QFN package. Refer to the MAX8702/
MAX8703 for compatible drivers.
Features
o 3-/4-Phase Interleaved Fixed-Frequency
Controller
o ±0.75% V_OUT Accuracy Over Line, Load, and
Temperature
o 5-Bit On-Board Digital-to-Analog Converter
(DAC)—0.80V to 1.55V
o Adjustable Suspend Voltage Input
o Active Voltage Positioning with Adjustable Gain
and Offset
o Accurate Lossless Current Balance
o Accurate Droop and Current Limit
o Remote Output and Ground Sense
o Output Slew-Rate Control
o Power-Good Window Comparator
o Selectable 200kHz/300kHz/600kHz Switching
Frequency
o Output Overvoltage and Undervoltage Protection
o Thermal Fault Protection
o 2V ±0.7% Reference Output
o Soft-Startup and Shutdown
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8707ETL -40°C to +85°C 40 Thin QFN 6mm x 6mm
Applications
AMD Hammer Desknote Computers
Multiphase CPU Core Supplies
Voltage-Positioned Step-Down Converters
Notebook/Desktop Computers
Servers
Pin Configuration appears at end of data sheet.
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