The MAX8525 (VRM 10/VRD 10)/MAX8524 (VRM 9.1/VRD 9.1) current-mode step-down controllers, the MAX8523 high-speed, dual-phase MOSFET gate driver,
and the MAX8552 wide-input, single-phase MOSFET
gate driver provide flexible, low-cost, low-voltage CPU
core supplies. The MAX8523 and MAX8552 high-speed,
high-current gate drivers allow operation at high switching
frequencies to reduce external component size and
cost for small-footprint, low-profile designs. Pin-selectable
2-, 3-, and 4-phase operation and master-slave 6- and 8-phase operation provide output-current scalability for servers, workstations, desktops, desk notes, and networking applications.
The switching frequency of the MAX8524/MAX8525 is
adjustable from 150kHz to 1.2MHz, permitting loop
bandwidths of up to 200kHz. Peak current-mode control
provides fast transient response and reduces cost.
A proprietary current-sharing scheme reduces current
imbalance between phases to less than 5% at full load.
The MAX8524/MAX8525 offer 0.4% initial accuracy and
remote-sense functionality. Both controllers also feature
programmable no-load offset and output-voltage positioning
to adjust the output voltage as a function of the
output current. The fast-active voltage positioning further
reduces bulk output capacitors and cost.
Current-mode control also simplifies compensation with
a variety of capacitors by eliminating the output-filter
double pole associated with voltage-mode controllers.
Both devices are compatible with electrolytic, tantalum,
polymer, and ceramic capacitors. Output current sensing
eliminates issues associated with controllers that
use high-side current sense and ensure stable and jitter-free operation. Temperature-compensated, lossless inductor current sense eliminates the need for a current-sense resistor and further reduces cost, while
maintaining voltage-positioning accuracy and reducing
power dissipation.
The MAX8525 features control VID voltage transition for
dynamic VID changes and eliminate both undervoltage
and overvoltage overshoot. The PWRGD signal is accurate
during VID code changes for the MAX8525 to
avoid any false fault signal.
Adjustable foldback current-limit and overvoltage protection
provide for a robust design.
Applications
- Desknotes and LCD PCs
- Desktop Computers
- High-End Switches and Routers
- Servers and Workstations
- Voltage-Regulator Modules
