Rainbow Electronics MAX773 - Manual

_______________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
♦ 90% Efficiency for 10mA to 1A Load Currents
♦ Up to 15W Output Power
♦ 110µA Max Supply Current
♦ 5µA Max Shutdown Current
♦ 2V to 16.5V Input Range
(MAX770/MAX771/MAX772)
♦ Internal Shunt Regulator for High Input Voltages
(MAX773)
♦ Preset or Adjustable Output Voltages
MAX770: 5V or Adjustable
MAX771: 12V or Adjustable
MAX772: 15V or Adjustable
MAX773: 5V, 12V, 15V, or Adjustable
♦ Current-Limited PFM Control Scheme
♦ 300kHz Switching Frequency
______________Ordering Information
Ordering Information continued at end of data sheet.
*Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883B.
MAX770–MAX773
5V/12V/15V or Adjustable, High-Efficiency,
Low I Q , Step-Up DC-DC Controllers
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
8
7
6
5
CS
GND
AGND
REF SHDN
FB
V+
EXT
MAX770
MAX771
MAX772
DIP/SO
_________________Pin Configurations
FB AGND GND
V+
CS
EXT N
REF
SHDN ON/OFF
OUTPUT
12V
INPUT
2V TO VOUT
MAX771
__________Typical Operating Circuit
PART TEMP. RANGE PIN-PACKAGE
MAX770 CPA 0°C to +70°C Plastic DIP
MAX770CSA 0°C to +70°C 8 SO
MAX770C/D 0°C to +70°C Dice*
MAX770EPA -40°C to +85°C 8 Plastic DIP
MAX770ESA -40°C to +85°C 8 SO
MAX770MJA -55°C to +125°C 8 CERDIP**
TOP VIEW
Pin Configurations continued at end of data sheet.
19-0202; Rev 2; 11/96
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
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