# Ways to multiplex the output of a DAC?

Part searching in microcontrollers, it looks like most small ones have at most one DAC. What is the just way or ways to output multiple slow signals from a microcontroller with at most a single DAC?

For instance, what if I'm trying to output 4 signals with up to 100Hz bandwidth and 8 bits of resolution?

Here are the solutions I've come up with:

1. Use an analog switch with an amplifier doing track and hold for each output. Unfortunately, this requires the most board space probably, and the charge injection from the switch and bias current of the amplifiers require some moderately large capacitors (at least nF).

2. Use a dedicated sample and hold amplifier for each output. Unfortunately, the cheapest ones are in the 70 cent range at quantity, and I'd need at least two.

3. Just buy a DAC with multiple outputs. Unfortunately, the cheapest 2-output DAC seems to be in the 60-70 cent range at quantity, the same as the microcontroller.

• Use a PWM type signal and RC low pass filter if accuracy isn’t the top of the list. Jan 17 '20 at 19:33
• yeah, how to multiplex something is usually a question of what you need to achieve: what's the necessary bandwidth of your outputs, what's their purpose? Jan 17 '20 at 19:42

• Cheapest single quantity single channel sample and hold amp $1.65 LF398MX • 4 Channel 12 bit buffered I2C DAC is$1.89 (less than \$0.50 per channel) MCP4728T-E/UN