Discrete +5 To -15 V Converter

This negative voltage converter differs from a host of other designs in not being set up around the latest integrated cir- cuit. The circuit diagram shows that only a handful of commonly available parts are required to build an efficient +5 to -15 V converter. IC: functions as a self-oscillating multi- vibrator that supplies an output signal with a relatively high duty factor. The LM311 is designed to operate from a single 5 V supply, and has a high output current capability for driving switching transistor T1. Duty factor of the output signal is determined mainly by voltage divider R2-R3, and frequency of oscil- lation by C2-R4. Transistor T2 forms part of a regulation loop that modifies the os- cillator duty factor to maintain -15 V at the output of the converter. The output voltage, Uo, is calculated from U0= - (UD1+ UB-E(T1))(R.13/R9 + 1) [V] The component values shown give the following design data: 5V/1A 0 Efficiency (Po/Pi): Oscillator frequency: Duty factor: Output r...