#370 DigitaSwitch/TS3A5018

Testing the TS3A5018 Quad SPDT Analog Switch with a simple 555 timer and Arduino demo.

Build

Here’s a quick demo..

Notes

Digital switches seem to be well suited for switching applications that are more complex than can be achieved with a simple FET or BJT, but lower power than might be more suited to a relay. Particular applications I have in mind are switching amplifier gain stages, filter gangs, and circuit subsystems.

They are available in a range of pole/throw configuration, and importantly with defined make-before-break or break-before-make behaviour.

I’m testing a TS3A5018 here, which I obtained already populated on a convenient breakout module.

The TS3A5018 is a 1.8 to 3.6V device with four SPDT switches controlled from a single input, and a master active-low enable pin. It is guaranteed break-before-make (max 58ns).

TS3A5018_block_diagram

Code Example

The TS3A5018.ino sketch uses two of the switches in a simple demonstration with an Arduino Uno and 555 timer:

one switch alters the timing capacitor in a 555 astable oscillator, switching the frequency from 1 Hz to 2.4 Hz
another switch changes the LED (color) running on the oscillator output

The TS3A5018 is only rated for 1.8 to 3.6V, so a 3.3V rail is used for the offboard circuit, and simple voltage divider level-shifts the Arduino output pin.

Construction

Breadboard

Schematic