Description:
A charge-pump based voltage inverter module for low-power loads. This module has an unregulated output.
Circuit description:
A 555 timer configured as a square wave oscillator from which the output directly drives an inverting charge pump C4-D1-D2. The output voltage is smoothed by capacitor C3. The impedance of the circuit is dependent on the value of C4 and the frequency of oscillation. The circuit operates at approximately 40kHz with the shown component values.
Table 1: Component function
| R1,R2,C6 |
Timing components. These set the frequency of the oscillator, and the ratio of R1:R2 set the duty cycle. The values shown are for a 40kHz square wave. |
| C1,2 |
These provide high and low frequency suppy decoupling respectively. |
| C3 |
Output smoothing capacitor. |
| C4 |
Charge pump capacitor. |
| C5 |
Control voltage decoupling capacitor. |
| D1,2 |
Charge pump diodes. |
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