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 efficiency.
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 currentsense
inputs for each phase and includes a fifth pair of
current-sense inputs to provide an accurate voltagepositioning
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 transitions
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 negative
output undershoot. The MAX8707 includes output
fault protection—undervoltage, nonlatched overvoltage,
and thermal overload—and an independent voltageregulator
power-OK (VROK) output.
The MAX8707 has a selectable switching frequency,
allowing 200kHz, 300kHz, or 600kHz per-phase operation.
The MAX8707 is available in the low-profile, 40-pin,
6mm x 6mm thin QFN package. Refer to the MAX8702/MAX8703 for compatible drivers.
Applications
- AMD Hammer Desknote Computers
- Multiphase CPU Core Supplies
- Notebook and Desktop Computers
- Servers
- Voltage-Positioned Step-Down Converters
