The chip I am using now is nRF52820, which only has a common comparator and no ADC.
But I didn't find the accuracy. Such as ADC(12-bit, 200 ksps ADC).
In software, I use single-ended mode, internal reference voltage.
I can't monitor the fluctuation of 0.001v when I do experiments with DC power supply.
So I want to know the accuracy of this comparator.
Hello,
Thank you for contacting DevZone at NordicSemi.
A comparator typically switches the output level when the delta-V (V+ - V-) crosses through (~) zero volts. However, it is important to note that the small voltage fluctuations are always present on input and therefore, due to the noise, output would switch and cause undesirable effects when the delta-V is (very small and) near to the zero voltage.
To remove undesirable glitches in the output, a small hysteresis value is used in comparators. This introduces VUP and VDOWN tripping points around reference. Now looking at product specification of nrf52820, it provides fully flexible hysteresis using a 64-level reference ladder.
In single-ended mode, you need to set TH register (offset: 0x530) along with other registers. The reference ladder uses the reference voltage (VREF) to derive two new voltage references, VUP and VDOWN. VUP and VDOWN are configured using THUP and THDOWN of the TH register.
You can use minimum hysteresis by using value of 0 for THDOWN and THUP (as per equations)
Please note that HYST (offset: 0x538) register has no effect in single-ended mode, and the content of this register are ignored.
Regards,
Naeem
