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STM8L ADC Input drawing current

Question asked by addy.richard on Jan 25, 2017
Latest reply on Jan 31, 2017 by addy.richard

I’m using the STM8L052r8 to measure temperatures on the ADC channels 24/25. I’m using a proven ADC routine but my expected counts aren’t coming in correct.

 

It seems I've got a volt drop/ current flow across R1 on the input to the ADC pin.

Could anyone tell me what internal resistance there is in the micro from the ADC input to ground please, and the kind of current I can expect to be flowing there.

 

I have the ADC pins configured as input floating, with the Schmitt trigger disabled.

The temperature probe is connected across THP1 and THM1. R2 is the drive resistor 9k09, R2 is a 1k in series with the ADC input.

 

Really simple I bet but I'm pretty new to this.

Thanks in advance, RichardADC input

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