This is a design circuit for positive to negative converter. The negative feedback (NFB) pin, enables negative output regulators to be designed using direct feedback. In the circuit shown in Figure 3, a 2.7 V to 13 V input, –5 V output converter, the output is monitored by the NFB pin and a simple divider network. No complex level shifting or unusual grounding techniques are required. The S/S pin is used to synchronize the switching frequency to a 600 KHz external clock signal. This is the figure of the circuit.
The switch clamp diodes, D2 and D3, prevent the leakage spike from the transformer, T1, from exceeding the switch’s absolute maximum voltage rating. The Zener voltage of D2 must be higher than the output voltage, but low enough that the sum of input voltage and clamp voltage does not exceed the switch-voltage rating.
The switch clamp diodes, D2 and D3, prevent the leakage spike from the transformer, T1, from exceeding the switch’s absolute maximum voltage rating. The Zener voltage of D2 must be higher than the output voltage, but low enough that the sum of input voltage and clamp voltage does not exceed the switch-voltage rating.
