MAX1744 Datasheet, PDF (1/14 Pages) Maxim Integrated Products – High-Voltage, Step-Down DC-DC Controller in uMAX

19-1776; Rev 1; 10/01
High-Voltage, Step-Down DC-DC
Controller in µMAX
General Description
The MAX1744/MAX1745 are step-down DC-DC con-
trollers capable of handling up to 36V inputs. These
parts use a proprietary current-limited control scheme
for excellent light- and full-load efficiency, while their
330kHz (max) switching frequency permits small exter-
nal components for space-critical applications.
Operation to 100% duty cycle permits the lowest possi-
ble dropout voltage.
The MAX1744 contains an internal feedback network
that provides a pin-selectable output voltage of either
3.3V or 5V. The MAX1745 uses an external feedback
network to generate an adjustable output voltage
between 1.25V and 18V.
The MAX1744/MAX1745 are available in a space-sav-
ing 10-pin µMAX package.
________________________Applications
Automotive Electronics
Telecom Systems
Wall-Cube-Powered Devices
Industrial Control Systems
Firewire/IEEE1394
Typical Operating Circuit
IN
4.5V TO 36V
____________________________Features
o High-Voltage Operation (up to 36V IN)
o Efficiency >90%
o Output Power Capability Exceeds 50W
o 10-Pin µMax Package
o Low-Dropout Voltage
o 100% (max) Duty Cycle
o 90µA Quiescent Current
o 4µA Shutdown Current
o Up to 330kHz Switching Frequency
o Output Voltage
5V or 3.3V (MAX1744)
Adjustable 1.25V to 18V (MAX1745)
o Current-Limited Control Scheme
PART
MAX1744EUB
MAX1744AUB
MAX1745EUB
MAX1745AUB
TOP VIEW
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +125°C
-40°C to +85°C
-40°C to +125°C
PIN-PACKAGE
10 µMAX
10 µMAX
10 µMAX
10 µMAX
Pin Configuration
ON
IN VH EXT
P
OFF
SHDN
5V
3.3V
3/5
MAX1744
VL
REF
CS
GND ^OUT
OUT
3.3V
OR 5V
GND 1
VL 2
REF 3
3/5 (FB) 4
OUT 5
( ) ARE FOR MAX1745 ONLY.
MAX1744
MAX1745
µMAX
10 IN
9 EXT
8 VH
7 SHDN
6 CS
________________________________________________________________ Maxim Integrated Products 1
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