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### Author Topic: help with UAA2016 app circuiit from data sheet  (Read 3183 times)

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#### MrDEB

• Guest
##### help with UAA2016 app circuiit from data sheet
« on: October 17, 2011, 04:57:19 AM »
I contacted ON semiconductor but no luck.
Want to use the UAA2016 zero voltage switch in a temp ctr soldering iron but how to use??
Here is the circuit I tried to get working but to no avail.
http://www.n0ss.net/hakko_936_schem-pcb_&_mod_v1r7.pdf
Going with a PIC, Hakko 907 iron but how to use the UAA2016??
I am lost big time with math.

#### kam

• Hero Member
• Posts: 1849
##### Re: help with UAA2016 app circuiit from data sheet
« Reply #1 on: October 20, 2011, 22:33:27 PM »
That's a very nice chip! I never knew this before! I checked the datasheet, and i think i will get some of those for stock. I wish i knew them before, when i was designing my heater. Anyway. There is a nice typical application in page 3 of the datasheet:

If i were you, i would start messing around with the chip by designing and testing this circuit. Then i would play with the Rs resistor. I do not think that you need to know how to solve the math for RL and ILOAD. This is what you need to work on (page 5):

Quote
Temperature Sensing (Pin 3)
The actual temperature is sensed by a negative temperature coefficient element connected in a resistor divider fashion. This two element network is connected between the ground terminal Pin 5 and the reference voltage − 5.5 V available on Pin 1. The resulting voltage, a function of the measured temperature, is applied to Pin 3 and internally compared to a control voltage whose value depends on several elements: Sawtooth, Temperature Reduction and Hysteresis Adjust. (Refer to Application Information.)

And of course you need to experiment with the hysteresis by R3 (pin 2)

I'm -almost- sure you do not need to mess with math. I wouldn't... Unless you want to know (predict) the current and thus the power consumption of the heater.