Triple Capacitive Voltage Inverter with the MAX871
Figure 1. Triple voltage inverter with MAX871.
The schematic of the design idea has been tested with 4.5V and 5V input voltage. Figure 2 shows load current vs. output voltage. The general voltage drop on VOUT is caused by the forward voltage of the external diodes of typically 0.3V to 0.4V per diode, depending on the load current. VOUT is:
VOUT = -3 × VIN + 4 × VD
VD: typically 0.3V to 0.4V
VIN is the input voltage on pin 2. VD is the forward voltage drop of diode D1 to D4. If Schottky diodes are used VD is typically 0.3V to 0.4V.
Figure 2. Load current vs. output voltage.
|C1 - C6||470nF ceramic|
|D1 - D4||BAT41|
A similar version of this article appeared in the October 25, 2001 issue of Electronic World and Wireless World magazine.