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Maxim > Design Support > Technical Documents > Application Notes > Analog Switches and Multiplexers > APP 130
Keywords: analog switches, low voltage, charge pump, voltage regulator, power supply, switching time,
transition time, analog switch, power supplies
APPLICATION NOTE 130
How Dual-Supply Analog Switches Can Operate
with a Single 3V or 5V Supply
Jul 09, 1998
Abstract: By adding a voltage doubler and voltage inverter, a single 3V or 5V power supply can produce
the voltages necessary to improve the performance on a dual voltage analog switch. With the higher
power supplies and wider range, the on-resistance and timing performance are enhanced.
By adding a single component to a 3V-only or 5V-only board, you can operate conventional CMOS
analog switches with performance approaching that specified with dual ±15V supplies. This simple
modification provides fast switching, low on-resistance, CMOS/TTL compatibility, low-power
consumption, and a signal range (±V
CC
) that exceeds the input supply range (V
CC
to ground).
Simply add a dual-output charge-pump voltage converter (IC1), which produces ±2V
CC
outputs from a
single V
CC
input. These unregulated voltages ensure reliable switch operation for V
CC
levels as low as
2.5V.
Figure 1. The MAX865 dual-output charge pump (IC1) provides a local bipolar power supply for the
MAX4659 CMOS analog switch (IC2).
A V
CC
supply voltage of 3V for the MAX865 charge pump produces ±6V rails for the switch (IC2). Using
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