Isolated Flyback Switching Regulator with 9V Output

The LT1424-9 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 LT1424-9 operates with input supply voltages from 3V to 20V and draws only 7mA quiescent current. It can deliver up to 200mA at 9V with no external power devices. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation.

The LT1424-9 has a number of features not found on other switching regulator ICs. Its unique control circuitry can maintain regulation well into discontinuous mode. Load compensation circuitry allows for improved load regulation. An externally activated shutdown mode reduces total supply current to 20µA typical for standby operation.

Applications

* Ethernet Isolated 5V to –9V Converter

* No Transformer “Third Winding” or Optoisolator Required* Application Circuit Meets PCMCIA Type II Height Requirement* Fixed, Application Specific 9V Output Voltage* Regulation Maintained Well into Discontinuous Mode (Light Load)* Load Compensation Provides Excellent Load Regulation* Available in 8-Pin PDIP and SO Packages* Operating Frequency: 285kHz