SAR Input voltage of 5V on a PSoC6

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rosenrot
Level 2
Level 2
5 replies posted 10 questions asked 25 sign-ins

Dear all,

the PSoC6 has a 5.6 kOhm pull-down resistor. I was wondering if this one can be used as the R2 in a voltage divider to enable a 5V analog input. Calculating a proper R1 value leads to 2.8 kOhm.

Why I would like to use the pull-down resistor? because I would like to use 16 input channels and saving resistors would be great.

The real question is. Would it work? If I programm the pins as analog inputs with pull-down resistors, are they set to this setting from power up? Anything else might destroy the pins right?

Any help is welcome.

 

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1 Solution
Andri-setyabudi
Level 5
Level 5
50 likes received 50 sign-ins 25 solutions authored

Hi @rosenrot , 

As explained by @ChiP_16 , not recommended to use internal pull-down resistor for your voltage divider on ADC. 
You will get damage your PSoC - pin.  You should make sure the analog voltage ( ADC ) does not exceed 3.3V before entering the pin.

Warm regards,


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2 Replies
ChiP_16
Employee
Employee
5 questions asked 5 likes given 5 solutions authored

Hi,

During power-on and reset, the pins are forced to the analog input drive mode, with input and output buffers disabled. The pins were subject to 5V (exceed specification) until it is configured to resistive pull down mode. 

Port 3 has 2  overvoltage tolerant pins.

 

 

Andri-setyabudi
Level 5
Level 5
50 likes received 50 sign-ins 25 solutions authored

Hi @rosenrot , 

As explained by @ChiP_16 , not recommended to use internal pull-down resistor for your voltage divider on ADC. 
You will get damage your PSoC - pin.  You should make sure the analog voltage ( ADC ) does not exceed 3.3V before entering the pin.

Warm regards,