MAX756 Datasheet, PDF (1/8 Pages) Maxim Integrated Products – 3.3V/5V/Adjustable-Output, Step-Up DC-DC Converters

19-0113; Rev. 2; 1/95
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3.3V/5V/Adjustable-Output,
Step-Up DC-DC Converters
_______________General Description
The MAX756/MAX757 are CMOS step-up DC-DC switch-
ing regulators for small, low input voltage or battery-pow-
ered systems. The MAX756 accepts a positive input
voltage down to 0.7V and converts it to a higher pin-
selectable 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
__________Typical Operating Circuit
____________________________Features
o Operates Down to 0.7V Input Supply Voltage
o 87% Efficiency at 200mA
o 60µA Quiescent Current
o 20µA Shutdown Mode with Active Reference and
LBI Detector
o 500kHz Maximum Switching Frequency
o ±1.5% Reference Tolerance Over Temperature
o Low-Battery Detector (LBI/LBO)
o 8-Pin DIP and SO Packages
______________Ordering Information
PART
MAX756CPA
MAX756CSA
MAX756C/D
MAX756EPA
MAX756ESA
MAX757CPA
MAX757CSA
MAX757C/D
MAX757EPA
MAX757ESA
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
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
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
* Dice are tested at T_A = +25°C only.
_________________Pin Configurations
INPUT
2V to VOUT
1
SHDN
150µF
5
LBI
8
LX
2
3/5
MAX756
6
OUT
OUTPUT
22µH
5V at 200mA
or
1N5817 _{3.3V at 300mA}
100µF
0.1µF
3
REF
4
LBO
GND
7
LOW-BATTERY
DETECTOR OUTPUT
TOP VIEW
SHDN 1
3/5 ²
REF ³
LBO ⁴
MAX756
DIP/SO
8 _LX
7 GND
6 OUT
5 _LBI
SHDN 1
FB ²
REF ³
LBO ⁴
MAX757
DIP/SO
8 _LX
7 GND
6 OUT
5 _LBI
________________________________________________________________ Maxim Integrated Products 1
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