MAX748A Datasheet, PDF (1/12 Pages) Maxim Integrated Products – 3.3V, Step-Down, Current-Mode PWM DC-DC Converters

19-0190; Rev 0; 9/93
3.3V, Step-Down,
Current-Mode PWM DC-DC Converters
__________________General Description
The MAX748A/MAX763A are 3.3V-output CMOS, step-
down switching regulators. The MAX748A accepts
inputs from 3.3V to 16V and delivers up to 500mA. The
MAX763A accepts inputs between 3.3V and 11V and
delivers up to 500mA. Typical efficiencies are 85% to
90%. Quiescent supply current is 1.4mA (MAX763A),
and only 0.2µA in shutdown.
Pulse-width-modulation (PWM) current-mode control pro-
vides precise output regulation and excellent transient
responses. Output voltage accuracy is guaranteed to be
±5% over line, load, and temperature variations.
Fixed-frequency switching allows easy filtering of output
ripple and noise, as well as the use of small external
components. A 22µH inductor works in most applica-
tions, so no magnetics design is necessary.
The MAX748A/MAX763A also feature cycle-by-cycle cur-
rent limiting, overcurrent limiting, undervoltage lockout,
and programmable soft-start protection. The MAX748A
is available in 8-pin DIP and 16-pin wide SO packages;
the MAX763A comes in 8-pin DIP and SO packages.
___________________________Applications
5V-to-3.3V Converters
Cellular Phones
Portable Instruments
Hand-Held Computers
Computer Peripherals
________________________________Features
o Up to 500mA Load Currents
o Guaranteed 159kHz to 219.5kHz Current-Mode
PWM
o 85% to 90% Efficiencies
o 1.7mA Quiescent Current (MAX748A)
1.4mA Quiescent Current (MAX763A)
o 0.2µA Shutdown Supply Current
o 22µH Preselected Inductor Value;
No Component Design Required
o Overcurrent, Soft-Start, and Undervoltage
Lockout Protection
o Cycle-by-Cycle Current Limiting
o 8-Pin DIP/SO Packages (MAX763A)
_________________Ordering Information
PART
MAX748ACPA
MAX748ACWE
MAX748AC/D
MAX748AEPA
MAX748AEWE
MAX748AMJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
16 Wide SO
Dice*
8 Plastic DIP
16 Wide SO
8 CERDIP
Ordering Information continued on last page.
* Contact factory for dice specifications.
____________Typical Operating Circuit
INPUT
3.3V TO 16V
V+
LX
22µH
OUTPUT
3.3V
ON/OFF
MAX748A
SHDN
OUT
REF
SS
CC
GND
100µF
____________________Pin Configurations
TOP VIEW
SHDN 1
REF 2
SS 3
CC 4
MAX748A
MAX763A
DIP
8 V+
7 LX
6 GND
5 OUT
Pin Configurations continued on last page.
_______________________________________________________________________ Maxim Integrated Products 1
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