The LT1425 is a monolithic high power switching regulator specifically designed for the isolated flyback topology. No “third winding” or optoisolator is required; the integrated circuit senses the isolated output voltage directly from the primary side flyback waveform. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. The LT1425 operates with input supply voltages from 3V to 20V and draws only 7mA quiescent current. It can deliver output power up to 6W with no external power devices. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. The LT1425 has a number of features not found on other switching regulator ICs. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load compensation circuitry allows for improved load regulation. An externally activated shutdown mode reduces total supply current to 15µA for standby operation.
The LT1425 is a monolithic high‑power switching regulator designed for isolated flyback topologies. It eliminates the need for a third transformer winding or optoisolator by sensing the isolated output voltage directly from the primary side flyback waveform. The device includes an internal high‑current switch, oscillator, control, and protection circuitry, and operates from 3 V to 20 V input while delivering up to 6 W of output power.
The datasheet provides complete electrical characteristics, pin descriptions, typical application circuits, and package information for the 16‑lead narrow‑SO package. It also covers absolute maximum ratings, timing requirements, and optional load‑compensation features for improved regulation in discontinuous mode.
| Input Voltage Range | 3 V to 20 V |
|---|---|
| Maximum Output Power | 6 W |
| Quiescent Current | 7 mA |
| Switching Frequency | 285 kHz |
| Shutdown Mode Supply Current | 15 µA |
| Package | 16‑Lead Plastic Small Outline (Narrow 0.150) |
The LT1425 operates at a switching frequency of 285 kHz.
It supports input voltages from 3 V up to 20 V.
In shutdown mode the device draws about 15 µA.
The LT1425 is supplied in a 16‑lead plastic narrow‑SO package.