MAX1953 Datasheet, PDF (1/22 Pages) Maxim Integrated Products – Low-Cost, High-Frequency, Current-Mode PWM Buck Controller

19-2373; Rev 0; 4/02
Low-Cost, High-Frequency, Current-Mode PWM
Buck Controller
General Description
The MAX1953/MAX1954/MAX1957 is a family of versa-
tile, economical, synchronous current-mode, pulse-width
modulation (PWM) buck controllers. These step-down
controllers are targeted for applications where cost and
size are critical.
The MAX1953 operates at a fixed 1MHz switching fre-
quency, thus significantly reducing external component
size and cost. Additionally, excellent transient response
is obtained using less output capacitance. The MAX1953
operates from low 3V to 5.5V input voltage and can sup-
ply up to 10A of output current. Selectable current limit is
provided to tailor to the external MOSFETs’ on-resistance
for optimum cost and performance. The output voltage is
adjustable from 0.8V to 0.86V_IN.
With the MAX1954, the drain-voltage range on the high-
side FET is 3V to 13.2V and is independent of the supply
voltage. It operates at a fixed 300kHz switching frequen-
cy and can be used to provide up to 25A of output cur-
rent with high efficiency. The output voltage is adjustable
from 0.8V to 0.86V_HSD.
The MAX1957 features a tracking output voltage range of
0.4V to 0.86V_IN and is capable of sourcing or sinking
current for applications such as DDR bus termination
and PowerPC™/ASIC/DSP core supplies. The MAX1957
operates from a 3V to 5.5V input voltage and at a fixed
300kHz switching frequency.
The MAX1953/MAX1954/MAX1957 provide a COMP pin
that can be pulled low to shut down the converter in
addition to providing compensation to the error amplifier.
An input undervoltage lockout (ULVO) is provided to
ensure proper operation under power-sag conditions to
prevent the external power MOSFETs from overheating.
Internal digital soft-start is included to reduce inrush cur-
rent. The MAX1953/MAX1954/MAX1957 are available in
tiny 10-pin µMAX packages.
Applications
Printers and Scanners
Graphic Cards and Video Cards
PCs and Servers
Microprocessor Core Supply
Low-Voltage Distributed Power
Telecommunications and Networking
†Patent Pending
PowerPC is a trademark of Motorola, Inc.
Features
o Low-Cost Current-Mode Controllers
o Fixed-Frequency PWM
o MAX1953
1MHz Switching Frequency
Small Component Size, Low Cost
Adjustable Current Limit
o MAX1954
3V to 13.2V Input Voltage
25A Output Current Capability
93% Efficiency
300kHz Switching Frequency
o MAX1957
Tracking 0.4V to 0.86V_IN Output Voltage Range
Sinking and Sourcing Capability of 3A
o Shutdown Feature
o All N-Channel MOSFET Design for Low Cost
o No Current-Sense Resistor Needed
o Internal Digital^† Soft-Start
o Thermal Overload Protection
o Small 10-Pin µMAX Package
Ordering Information
PART
MAX1953EUB
MAX1954EUB
MAX1957EUB
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
10 µMAX
10 µMAX
Pin Configurations
TOP VIEW
ILIM 1
COMP 2
FB 3
GND 4
IN 5
MAX1953EUB
10 BST
9 LX
8 DH
7 PGND
6 DL
µMAX
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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