MAX8524 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – 2- to 8-Phase VRM 10/9.1 PWM Controllers with Precise Current Sharing and Fast Voltage Positioning

19-2855; Rev 2; 4/05
2- to 8-Phase VRM 10/9.1 PWM Controllers
with Precise Current Sharing and Fast Voltage
Positioning
General Description
Features
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 switch-
ing frequencies to reduce external component size and
cost for small-footprint, low-profile designs. Pin-selec-
table 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 net-
working 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 con-
trol provides fast transient response and reduces cost.
A proprietary current-sharing scheme reduces current
imbalance between phases to less than 5% at full load.
♦ VRD/VRM 10 (MAX8525)
♦ VRD/VRM 9.1 (MAX8524)
♦ Fastest Load-Transient Response
♦ Rapid-Active Average Current Sensing
Better than 5% Current Balance
Fastest Voltage Positioning
♦ ±0.4% Initial Output-Voltage Accuracy
♦ Pin-Selectable 2-/3-/4-Phase Operation
♦ Master-Slave 6-/8-Phase Operation
♦ Differential Remote Voltage Sensing
♦ Dynamic VID Change (MAX8525)
♦ Adjustable, Foldback Current Limit
♦ Soft-Start and Soft-Stop
♦ Power-Good Output
♦ 150kHz to 1.2MHz Switching Frequency per Phase
The MAX8524/MAX8525 offer 0.4% initial accuracy and
remote-sense functionality. Both controllers also feature
programmable no-load offset and output-voltage posi-
tioning 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 sens-
ing eliminates issues associated with controllers that
use high-side current sense and ensure stable and jit-
ter-free operation. Temperature-compensated, lossless
inductor current sense eliminates the need for a cur-
rent-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 accu-
rate during VID code changes for the MAX8525 to
avoid any false fault signal.
Adjustable foldback current-limit and overvoltage pro-
tection provide for a robust design.
Applications
Servers, Workstations
Desktop Computers
Desk Notes and LCD PCs
Voltage-Regulator Modules
♦ 28-Lead QSOP Package
Ordering Information
PART
TEMP RANGE
MAX8524EEI
-40°C to +85°C
MAX8524EEI+
-40°C to +85°C
MAX8525EEI
-40°C to +85°C
MAX8525EEI+
-40°C to +85°C
+Denotes lead-free package.
PIN-PACKAGE
28 QSOP
28 QSOP
28 QSOP
28 QSOP
Pin Configurations
TOP VIEW
PWM3 1
PWM1 2
CS1+ 3
CS1_3- 4
CS3+ 5
VCC 6
GND 7
COMP 8
REF 9
ILIM 10
OSC 11
PWRGD 12
CLKO 13
CLKI 14
MAX8525
28 PWM2
27 PWM4
26 CS4+
25 CS2_4-
24 CS2+
23 RS+
22 RS-
21 EN
20 VID4
19 VID3
18 VID2
17 VID1
16 VID0
15 VID5
QSOP
Pin Configurations continued at end of data sheet.
High-End Switches and Routers
Functional Diagram appears at end of data sheet.
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