Optocoupler Driver Improves Power-Supply Control

An optocoupler driver IC for isolated power supplies requirING tight regulation, the LT4430 offers fast transient response and overshoot protection. The overshoot control circuit provides independent control of startup and short-circuit characteristics without compromising loop bandwidth and resultant transient response. Housed in a small, 6-pin SOT-23 package, the device incorporates a precision low-voltage reference (0.6V, ±0.75%), a 9-MHz error amplifier, an inverting optocoupler driver and the overshoot control circuit. It operates over a supply voltage range of 3V to 20V and delivers an output current up to 10 mA. Loop frequency compensation is simplified because the error amplifier’s high bandwidth of 9 MHz minimizes phase shift, and the ground-referenced optocoupler drive eliminates the secondary feedback path present with existing devices. The reference stability and error amplifier’s 80-dB open loop gain ensure tight dc regulation over all input line and load conditions. Operating temperature range is -40°C to +85°C. Price is $1.75 each/1,000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900, ext. 2593.