Rainbow Electronics MAX1771 - Manual

General Description
The MAX1771 step-up switching controller provides
90% efficiency over a 30mA to 2A load. A unique cur-
rent-limited pulse-frequency-modulation (PFM) control
scheme gives this device 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).
This controller uses miniature external components. Its
high switching frequency (up to 300kHz) allows sur-
face-mount magnetics of 5mm height and 9mm diame-
ter. It accepts input voltages from 2V to 16.5V. The
output voltage is preset at 12V, or can be adjusted
using two resistors.
The MAX1771 optimizes efficiency at low input voltages
and reduces noise by using a single 100mV current-limit
threshold under all load conditions. A family of similar
devices, the MAX770–MAX773, trades some full-load
efficiency for greater current-limit accuracy; they provide
a 200mV current limit at full load, and switch to 100mV
for light loads.
The MAX1771 drives an external N-channel MOSFET
switch, allowing it to power loads up to 24W. If less power
is required, use the MAX756/MAX757 or MAX761/MAX762
step-up switching regulators with on-board MOSFETs. An
evaluation kit is available.
Applications
Positive LCD-Bias Generators
Flash Memory Programmers
High-Power RF Power-Amplifier Supply
Palmtops/Hand-Held Terminals
Battery-Powered Applications
Portable Communicators
Features
♦ 90% Efficiency for 30mA to 2A Load Currents
♦ Up to 24W Output Power
♦ 110µA (max) Supply Current
♦ 5µA (max) Shutdown Current
♦ 2V to 16.5V Input Range
♦ Preset 12V or Adjustable Output Voltage
♦ Current-Limited PFM Control Scheme
♦ Up to 300kHz Switching Frequency
♦ Evaluation Kit Available
Ordering Information
MAX1771
12V or Adjustable, High-Efficiency,
Low I Q , Step-Up DC-DC Controller
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
8
7
6
5
CS
GND
AGND
REF SHDN
FB
V+
EXT
TOP VIEW
MAX1771
DIP/SO
Pin Configuration
FB AGND GND
V+
CS
EXT N
REF
SHDN ON/OFF
OUTPUT
12V
INPUT
2V TO V OUT
MAX1771
Typical Operating Circuit
PART TEMP RANGE PIN-PACKAGE
MAX1771CPA 0°C to +70°C 8 Plastic DIP
MAX1771CSA 0°C to +70°C 8 SO
MAX1771C/D 0°C to +70°C Dice*
MAX1771EPA -40°C to +85°C 8 Plastic DIP
MAX1771ESA -40°C to +85°C 8 SO
MAX1771MJA -55°C to +125°C 8 CERDIP**
19-0263; Rev 2; 3/02
EVALUATION KIT MANUAL
AVAILABLE
* Contact factory for dice specifications.
** Contact factory for availability and processing to MIL-STD-883B.
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.