Rainbow Electronics MAX5071 - Manual

General Description
The MAX5070/MAX5071 BiCMOS, high-performance,
current-mode PWM controllers have all the features
required for wide input voltage range isolated/nonisolated
power supplies. These controllers are used for low- and
high-power universal input voltage and telecom power
supplies.
The MAX5070/MAX5071 contain a fast comparator with
only 60ns typical delay from current sense to the output
for overcurrent protection. The MAX5070A/MAX5070B
have an integrated error amplifier with the output at
COMP. Soft-start is achieved by controlling the COMP
voltage rise using external components.
The frequency is adjustable from 20kHz to 1MHz with
an external resistor and capacitor. The timing capacitor
discharge current is trimmed allowing for programma-
ble dead time and maximum duty cycle for a given fre-
quency. The available saw-toothed waveform at R
T
C
T
can be used for slope compensation when needed.
The MAX5071A/MAX5071B include a bidirectional syn-
chronization circuit allowing for multiple controllers to
run at the same frequency to avoid beat frequencies.
Synchronization is accomplished by simply connecting
the SYNC pins of all devices together. When synchro-
nizing with other devices, the MAX5071A/MAX5071B
with the highest frequency synchronizes the other
devices. Alternatively, the MAX5071A/MAX5071B can
be synchronized to an external clock with an open-
drain output stage running at a higher frequency.
The MAX5071C provides a clock output pulse
(ADV_CLK) that leads the driver output (OUT) by
110ns. The advanced clock signal is used to drive the
secondary-side synchronous rectifiers.
The MAX5070/MAX5071 are available in 8-pin µMAX ®
and SO packages and operate over the automotive tem-
perature range of -40°C to +125°C.
Applications
Universal Input AC/DC Power Supplies
Isolated Telecom Power Supplies
Isolated Power-Supply Modules
Networking Systems
Computer Systems/Servers
Industrial Power Conversion
Isolated Keep-Alive Circuits
Features
♦ Pin-for-Pin Replacement for UC2842 (MAX5070A)
and UC2844 (MAX5070B)
♦ 2A Drive Source and 1A Sink Capability
♦ Up to 1MHz Switching Frequency Operation
♦ Bidirectional Synchronization
(MAX5071A/MAX5071B)
♦ Advanced Output Drive for Secondary-Side
Synchronous Rectification (MAX5071C)
♦ Fast 60ns Cycle-by-Cycle Current Limit
♦ Trimmed Oscillator Capacitor Discharge Current
Sets Maximum Duty Cycle Accurately
♦ Accurate 5% Start and Stop Voltage with 6V
Hysteresis
♦ Low 32µA Startup Current
♦ 5V Regulator Output (VREF) with 20mA Capability
♦ Overtemperature Shutdown
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
________________________________________________________________ Maxim Integrated Products 1
OUT
GND R T /C T
1
2
8
7
VREF
V
CC
FB
CS
COMP
µ MAX/SO
TOP VIEW
3
4
6
5
MAX5070A
MAX5070B
Pin Configurations
Ordering Information
19-3283; Rev 1; 6/04
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.
Ordering Information continued at end of data sheet.
Selector Guide appears at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX5070 AASA -40°C to +125°C 8 SO
MAX5070AAUA -40°C to +125°C 8 µMAX
MAX5070BASA -40°C to +125°C 8 SO
MAX5070BAUA -40°C to +125°C 8 µMAX
Pin Configurations continued at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.