BQ79616-Q1: Thermistor RC Filter Range

Andrew Fillingim

Part Number: BQ79616-Q1

Tool/software:

In the reference docs, it is mentioned that an RC filter can be added to the GPIOs when using thermistors. The suggested values are a R = 1 kOhm and C = 0.1-1 uF, which makes the RC constant between 1-10 kHz.

Would there be any issue with increasing either the R or C values to get an RC constant of 100 Hz?
Are there minimal current requirements for the gpio that would limit the how large the R value could be?
Would there be a better combo of values for this IC
1. R= 5 kOhm and C = 2 uF
2. R= 10 kOhm and C = 1 uF
3. R= 1 kOhm and C = 10 uF

Thanks,

Andrew

7 months ago

0 Abdelrahman Aldmour 7 months ago

TI__Intellectual 1520 points

Hey Andrew,

I will get back with you tomorrow on this.

Best regards,

Abdel

0 Andrew Fillingim 7 months ago in reply to Abdelrahman Aldmour

Prodigy 30 points

Hi Abdel,

Have you had a chance to look at this?

Thanks,
Andrew

0 Abdelrahman Aldmour 7 months ago in reply to Andrew Fillingim

TI__Intellectual 1520 points

Hello Andrew,

1. So the customer can totally increase the RC filter but will have to take into account that this will also increase the time it take for the GPIO to be pulled low or high during the GPIO's open wire detection cycle. Mainly the increase in the wait time is due to increasing capacitance. The increase in the resistance would increase the voltage drop.

2. There is a GPIO leakage current that will constantly drain the capacitors so the customer can use this to determine how long it takes the caps to drain

3. The chosen filter ultimately depends on the customers FTDI cycle requirements

Best regards,

Abdel

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BQ79616-Q1: Thermistor RC Filter Range