19-3154; Rev 0; 2/04
Low-Cost, Current-Mode PWM Buck
Controller with Foldback Current Limit
General Description
Features
The MAX1954A synchronous current-mode, pulse-
width modulation (PWM) buck controller is pin compati-
ble with the popular MAX1954 and is suitable for
applications where cost and size are critical.
♦ Current-Mode Controller
♦ Fixed-Frequency PWM
♦ Foldback Current Limit
The MAX1954A operates from an input voltage range of
3.0V to 13.2V, independent of the IC supply. The output
voltage is adjustable down to 0.8V. The IC operates at
a fixed 300kHz switching frequency and provides up to
25A of output current with efficiency up to 95%. This
controller has excellent transient response resulting in
smaller output capacitance.
♦ Output Down to 0.8V with ±1% FB Accuracy
♦ 3.0V to 13.2V Input Voltage
♦ 300kHz Switching Frequency
♦ 25A Output-Current Capability
♦ 93% Efficiency
♦ All-N-Channel-MOSFET Design for Low Cost
♦ No Current-Sense Resistor Needed
♦ Internal Digital Soft-Start
The MAX1954A features foldback current limiting that
greatly reduces input current and component power
dissipation during output overload or short-circuit
conditions.
The compensation and shutdown control (COMP) input,
in addition to providing compensation to the error
amplifier, can be pulled low to shut down the converter.
An input undervoltage lockout is provided to ensure
proper operation during power sags to prevent the
external power MOSFETs from overheating. Internal
digital soft-start is included to reduce inrush current
and save an external capacitor.
♦ Small 10-Pin µMAX Package
The MAX1954A is available in a tiny 10-pin µMAX pack-
age to minimize PC board space.
Applications
Printers and Scanners
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
Graphic Cards and Video Cards
PCs and Servers
MAX1954AEUB
-40°C to +85°C
10 µMAX
Microprocessor Cores
Low-Voltage Distributed Power
Telecom/Networks
Pin Configuration
TOP VIEW
HSD
COMP
FB
1
2
3
4
5
10 BST
9
8
7
6
LX
MAX1954A
DH
GND
IN
PGND
DL
µMAX
________________________________________________________________ Maxim Integrated Products
1
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.