EVALUATION KIT AVAILABLE
MAX756/MAX757
3.3V/5V/Adjustable-Output,
Step-Up DC-DC Converters
_______________General Description
The MAX756/MAX757 are CMOS step-up DC-DC switching regulators for small, low input voltage or battery-powered systems. The MAX756 accepts a positive input
voltage down to 0.7V and converts it to a higher pinselectable output voltage of 3.3V or 5V. The MAX757 is
an adjustable version that accepts an input voltage down
to 0.7V and generates a higher adjustable output voltage
in the range from 2.7V to 5.5V. Typical full-load efficiencies
for the MAX756/MAX757 are greater than 87%.
The MAX756/MAX757 provide three improvements over
previous devices. Physical size is reduced—the high
switching frequencies (up to 0.5MHz) made possible by
MOSFET power transistors allow for tiny (<5mm diameter)
surface-mount magnetics. Efficiency is improved to 87%
(10% better than with low-voltage regulators fabricated in
bipolar technology). Supply current is reduced to 60µA
by CMOS construction and a unique constant-off-time
pulse-frequency modulation control scheme.
________________________Applications
3.3V to 5V Step-Up Conversion
Palmtop Computers
Portable Data-Collection Equipment
Personal Data Communicators/Computers
Medical Instrumentation
2-Cell & 3-Cell Battery-Operated Equipment
Glucose Meters
Functional Diagrams
__________Typical Operating Circuit
INPUT
2V to VOUT
____________________________Features
♦ Operates Down to 0.7V Input Supply Voltage
♦ 87% Efficiency at 200mA
♦ 60µA Quiescent Current
♦ 20µA Shutdown Mode with Active Reference and
LBI Detector
♦ 500kHz Maximum Switching Frequency
♦ ±1.5% Reference Tolerance Over Temperature
♦ Low-Battery Detector (LBI/LBO)
♦ 8-Pin DIP and SO Packages
______________Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX756CPA
0°C to +70°C
8 Plastic DIP
MAX756CSA
MAX756C/D
MAX756EPA
MAX756ESA
MAX757CPA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
MAX757CSA
MAX757C/D
MAX757EPA
MAX757ESA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
8 SO
Dice*
8 Plastic DIP
8 SO
* Dice are tested at TA = +25°C only.
_________________Pin Configurations
TOP VIEW
SHDN
150μF
5
1
LBI
SHDN
LX
8
OUTPUT
22μH
5V at 200mA
or
1N5817 3.3V at 300mA
1
8
LX
3/5
2
7
GND
6
OUT
5
LBI
REF 3
LBO 4
DIP/SO
100μF
2
MAX756
3/5
OUT
MAX756
6
REF
LBO
4
LOW-BATTERY
DETECTOR OUTPUT
GND
0.1μF
Pin Configurations appear at end of data sheet.
7
Functional Diagrams continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
1
8
LX
FB
3
SHDN
2
7
GND
6
OUT
5
LBI
REF 3
MAX757
LBO 4
DIP/SO
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-0113; Rev. 2; 1/95
