Part number: 20 Haos Redro Last update: 27/10/2009

Low current voltage inverter module

Resources:

40 Overall schematic FIG | PDF
41 PCB layout FIG | PDF (copper) | PDF (copper+component)

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.

PCB layout:

The PCB is 33mm long and 21mm wide and uses a single-sided layout. The connectors are aligned with the bottom edge of the board so that the module can be fitted to a motherboard uisng right angle SIL pins.

Images:


Completed module
Copyright © 2009 Taiyo Rawle. This document is released under the terms of the TAPR Open Hardware License version 1.0 or at your option any later version as published by TAPR: http://www.tapr.org/ohl.html