MAX770 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers

19-0202; Rev 2; 11/96
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5V/12V/15V or Adjustable, High-Efficiency,
Low I_Q, Step-Up DC-DC Controllers
_______________General Description
The MAX770–MAX773 step-up switching controllers pro-
vide 90% efficiency over a 10mA to 1A load. A
unique current-limited pulse-frequency-modulation (PFM)
control scheme gives these devices the benefits of
pulse-width-modulation (PWM) converters (high efficiency
at heavy loads), while using less than 110µA of supply
current (vs. 2mA to 10mA for PWM converters).
These ICs use tiny external components. Their high
switching frequencies (up to 300kHz) allow surface-
mount magnetics of 5mm height and 9mm diameter.
The MAX770/MAX771/MAX772 accept input voltages
from 2V to 16.5V. Output voltages are preset at 5V,
(MAX770), 12V (MAX771), and 15V (MAX772); they can
also be adjusted using two resistors.
The MAX773 accepts inputs from 3V to 16.5V. For a wider
input range, it features an internal shunt regulator that
allows unlimited higher input voltages. The MAX773’s out-
put can be set to 5V, 12V, or 15V, or it can be adjusted
with two resistors.
The MAX770–MAX773 drive external N-channel MOSFET
switches, allowing them to power loads up to 15W. If less
power is required, use the MAX756/MAX757 or
MAX761/MAX762 step-up switching regulators with on-
board MOSFETs.
________________________Applications
Palmtops/Handy-Terminals
High-Efficiency DC-DC Converters
Battery-Powered Applications
Positive LCD-Bias Generators
Portable Communicators
Flash Memory Programmers
____________________________Features
o 90% Efficiency for 10mA to 1A Load Currents
o Up to 15W Output Power
o 110µA Max Supply Current
o 5µA Max Shutdown Current
o 2V to 16.5V Input Range
(MAX770/MAX771/MAX772)
o Internal Shunt Regulator for High Input Voltages
(MAX773)
o Preset or Adjustable Output Voltages
MAX770: 5V or Adjustable
MAX771: 12V or Adjustable
MAX772: 15V or Adjustable
MAX773: 5V, 12V, 15V, or Adjustable
o Current-Limited PFM Control Scheme
o 300kHz Switching Frequency
______________Ordering Information
PART
MAX770CPA
MAX770CSA
MAX770C/D
MAX770EPA
MAX770ESA
MAX770MJA
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
Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
Ordering Information continued at end of data sheet.
*Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883B.
_________________Pin Configurations
__________Typical Operating Circuit
INPUT
2V TO VOUT
MAX771 ^EXT
N
ON/OFF
SHDN
CS
OUTPUT
12V
REF
V+
FB AGND GND
TOP VIEW
EXT ¹
V+ ²
FB ³
SHDN ⁴
MAX770
MAX771
MAX772
DIP/SO
8 _CS
7 GND
6 AGND
5 _REF
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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For small orders, phone [phone] ext. 3468.