Secondary-Side Optocoupler Driver

The LT4430 drives the opto-coupler that crosses the galvanic barrier in an isolated power supply. The IC contains a precision-trimmed reference, a high bandwidth error amplifier, an inverting gain of 6 stage to drive the optocoupler and unique overshoot control circuitry.

The LT4430’s 600mV reference provides ±0.75% initial accuracy and ±1.25% tolerance over temperature. A high bandwidth 9MHz error amplifier permits simple frequency compensation and negligible phase shift at typical loop crossover frequencies. The opto-coupler driver provides 10mA of output current and is short-circuit protected. A unique overshoot control function prevents output overshoot on start-up and short-circuit recovery with a single capacitor.

The LT4430 is available in the low profile 6-lead TSOT-23 package.

Applications

* 48V Input Isolated DC/DC Converters

* Isolated Telecommunication Power Systems

* Distributed Power Step-Down Converters

* Offline Isolated Power Supplies

* Industrial Control Systems

* Automotive and Heavy Equipment

* 600mV Reference (1.25% Over Temperature)

* Wide Input Supply Range: 3V to 20V

* Overshoot Control Function Prevents Output Overshoot on Start-Up and Short-Circuit Recovery

* High Bandwidth Error Amplifier Permits Simple Loop Frequency Compensation

* Ground-Referenced Opto-Coupler Drive

* 10mA Opto-Coupler Drive with Current Limiting

* Low Profile (1mm) ThinSOT™ Package