SWCU193A April 2023 – August 2024 CC2340R2 , CC2340R5 , CC2340R5-Q1
The purpose of hysteresis is to prevent rapid changes on the comparator output due to noise on the input. This is done by increasing the voltage difference of the signal input compared to the reference input. Because of this, hysteresis will affect the accuracy of the measurement and should be disabled before the measurement. This means that the hysteresis should be enabled by the comparator output going low, if the input signal is above the threshold before the measurement is done (e.g. supply monitoring where the signal is slowly dropping to the reference level). If the signal is rising towards the reference level, hysteresis should be enabled by the comparator output going high. This is accommodated by a control-bit where the user can select if the hysteresis should be enabled by a high or low comparator output signal.
The table below shows the possible permutations and the resulting necessary configuration of the hysteresis polarity and trig-level.
User Case | Hysteresis polarity | Hysteresis trig-level | |
---|---|---|---|
Divider on reference input | Signal starting high and going low | Positive (1) | Low (0) |
Divider on reference input | Signal starting low and going high | Negative (0) | High (1) |
Divider on signal input | Signal starting high and going low | Negative (0) | Low (0) |
Divider on signal input | Signal starting low and going high | Positive (1) | High (1) |