隔離電源與離線式PWM控制器參考設(shè)計指南

Quick Reference Guide for Isolated and Off-Line PWM Controllers and Other Useful Helper ICs

The MAX5021/MAX5022 current-mode PWM controllers
contain all the control circuitry required for the design
of wide input voltage range isolated power supplies.
These devices are well suited for use in universal input
(85VAC to 265VAC) off-line or telecom (-36VDC to
-72VDC) power supplies.
An undervoltage lockout (UVLO) circuit with large hysteresis
coupled with low startup and operating current
reduce power dissipation in the startup resistor and
allow use of ceramic bypass capacitors. The 262kHz
switching frequency is internally trimmed to ±12%
accuracy; this allows the optimization of the magnetic
and filter components resulting in compact, cost-effective
power supplies. The MAX5021 with 50% maximum
duty cycle and MAX5022 with 75% maximum duty
cycle are recommended for forward converters and flyback
converters, respectively. The MAX5021/MAX5022
are available in 6-pin SOT23, 8-pin μMAX, and 8-pin
DIP packages and are rated for operation over the
-40°C to +85°C temperature range.