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How to set temp of UAA2016 zero voltage controller

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JunglePython said:
Hello all,

I am a reptile keeper trying to make a proportional thermostat using the motorola zero voltage switch power controller UAA2016.

The data sheet can be found here:


My question is how do I adjust the set point.

Please help!


I glanced over the datasheet. You will want to wire it up the way they show in Figure 1. The sense pin is on a divider with a fixed resistor and an NTC resistor. Look at the graph in Figure 15. What you will want to do is pick an NTC, then based on your setpoint temperature and the -5.5V reference, you can pick the other fixed resistor(RDEF) that you will use in your divider. the NTC should be located remotely at the location you want to control temperature (i.e., in the cage somewhere but not next to the heat lamp!)

The other resistors and switches in the network shown in Figure 1 are just the temp reduction feature which you can leave out if you dont want to implement that feature. Your NTC is the actual sensing element and the way the chip knows what the temp is at, it provides a known reference voltage and reads the divided voltage at the sense pin. Then it will know whether or not to output the pulse signal to the triac (or whatever power device is used for switching the heat source)

The pot & R2 in the network are just for calibrating your setpoint. Looks like a useful device. I think I have an application for this as well. Who is the distributor for these parts? What do they cost in small quantities?
Thanks for the reply, I didnt know the symbol for a pot. Duh!

I got the controllers from Farnell online. They cost me just under $3.00 Australian each.

For my thermostat I have a 100k NTC thermistor.
Triac = BT137 500

I want a set point of 32C.
I would like a multiturn potentiometer for the set point adjustment.
Load of the heating cable is 300 Watts.

I will try to work out the values for all the other components now.

If I get stuck can I swap you some ic's for more advice?

cheers and thanks again

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