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 integrates the switch, oscillator, control and protection circuitry, eliminating the need for a third transformer winding or optoisolator.
Key features include an input range of 3 V‑20 V, up to 6 W output power, 285 kHz operating frequency, low 7 mA quiescent current, and a shutdown mode that reduces supply current to 15 µA. The device offers programmable output voltage, load‑compensation, and synchronization capabilities, making it suitable for isolated power supplies in Ethernet, medical, and telecom applications.
| Input voltage range | 3 V to 20 V |
|---|---|
| Operating frequency | 285 kHz |
| Quiescent current (normal mode) | 7 mA |
| Shutdown mode supply current | 15 µA |
| Maximum output power | 6 W |
| Switch voltage rating | 35 V |
The LT1425 operates at about 285 kHz.
It draws only 7 mA quiescent current.
In shutdown mode the supply current is reduced to roughly 15 µA.
The device can deliver up to 6 W of output power.