Inverting charge pump and a simple regulator
12 parts
Two supplies from one 5 V input. Inverting charge pump: a 20 kHz clock flips two voltage-controlled changeover switches (1 Ω each). Clock low: the 2.2 µF flying capacitor charges to 5 V between the input and ground. Clock high: its S1 side (left) is grounded and its S2 side (right) joins the 4.7 µF reservoir, pulling the output to about −5 V. A 10 kΩ load sets the drop.
- V1 5V
- S1 ≥2.5V
- C1 2.2µF
- S2 ≥2.5V
- CLK 5V·20kHz
- C2 4.7µF
- R1 10kΩ
- R2 1kΩ
- Z1 3.3V
- Q1
- R3 220Ω
- LED1