LT1425 Datasheet | Linear Technology

LT1425 Isolated Flyback Switching Regulator Features s s DESCRIPTION The LT ®1425 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 7m A 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 pensation circuitry allows for improved load regulation. An externally activated shutdown mode reduces total supply current to 15µA for standby operation. s s s s s s No Transformer “Third Winding” or Optoisolator Required ± 5% Accurate Output Voltage Without User Trims (See Circuit Below) Resistor Programmable Output Voltage Regulation Maintained Well Into Discontinuous Mode (Light Load) Optional Load pensation Operating Frequency: 285k Hz Easily Synchronized to External Clock Available in 16-Pin Narrow SO Package U APPLICATIONS s s s s Isolated Flyback Switching Regulators Ethernet Isolated 5V to - 9V Converters Medical Instruments Isolated Tele Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATION 5V to Isolated - 9VOUT 500V ISOLATION BARRIER 5V T1- 9.5 9.4 + V- OUTPUT VOLTAGE (V) 11 R1 22.6k 3 1% - - LT1425 15 6 4 C3 1000p F SHDN SYNC VC RREF ROP RCP SGND PGND 7 10 RFB - DALE LPE 4841-330MB R2 3.01k 1% 5 14 13 C4 0.1µF R3 15k + C1 100µF 10V D1 1N5819 C2...