21.3.1 Warm-up Time
The analog comparator is enabled by setting the EN bit in ACMPn_CTRL. The comparator requires some time to stabilize after it is
enabled. This time period is called the warm-up time. The warm-up period is self-timed and will complete within 5µs after EN is set.
During warm-up and when the comparator is disabled, the output level of the comparator is set to the value of the INACTVAL bit in
ACMPn_CTRL. When the warm-up time is over, the ACMPACT bit in ACMPn_STATUS is set to 1 to indicate that the comparator is
active.
An edge interrupt will be generated if the edge interrupt is enabled and the value set in INACTVAL differs from ACMPOUT when the
comparator transitions from warm-up to active.
Software should wait until the warm-up period is over before entering EM2 or EM3, otherwise no comparator interrupts will be detected.
EM1 can still be entered during warm-up. After the warm-up period is completed, interrupts will be detected in EM2 and EM3.
21.3.2 Response Time
There is a delay from when the input voltage changes polarity to when the output toggles. This delay is called the response time and
can be altered by increasing or decreasing the bias current to the comparator through the BIASPROG and FULLBIAS fields in the
ACMPn_CTRL register. The current and speed of the circuit increase as the values of FULLBIAS and BIASPROG are increased from
their minimum setting of FULLBIAS=0 BIASPROG=0b00000 to the maximum setting FULLBIAS=1 BIASPROG=0b11111 (maximum).
The setting of FULLBIAS has a greater affect on current and speed than the setting of BIASPROG. See the part datasheet for specific
current and response times related to the setting of these fields.
If FULLBIAS is set, to avoid glitches the highest hysteresis level should be used.
EFM32JG1 Reference Manual
ACMP - Analog Comparator
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