Introduction
This document focuses on Intersil’s solution for the flyback converter. An inexpensive approach with discrete circuitry has been adopted instead of an integrated solution. Low cost and optimal performance are the prime objectives.
Intersil’s superior industry-standard ISL684x family of PWM controllers would best serve the needs of this design. Some key features of this family of parts include:
• 40ns peak current sensing
• 1A MOSFET driver

ISL6844 was selected for its large UVLO hysteresis, UVLO start threshold, and the fact that the converter has been designed for a maximum operational duty cycle of 50%, thus protecting the IC by limiting the duty cycle in case of extreme fault conditions.

Specifications
• Operating Input Voltage: 24V DC ±10%
• Output Voltage: ±15V
• Output Current: 100mA
• Ripple: 50mVP-P
• Switching Frequency: 300kHz
• Topology: DCM Flyback