Datasheet MAX756, MAX757 (Maxim)

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