The OPAMPs can also be used during sleep modes. The 32KHz clock source used by the voltage doubler must remain active. See Voltage Doubler for more details.
Each OPAMP x can be configured to behave differently in different sleep modes. The behavior is determined by the individual Run in Standby and On Demand bits in the OPAMP Control x registers (OPAMPCTRLx.RUNSTDBY, and OPAMPCTRLx.ONDEMAND), as well as the common Enable bit in the Control A register (CTRLA.ENABLE).
| OPAMPCTRLx.RUNSTDBY | OPAMPCTRLx.ONDEMAND | CTRLA.ENABLE | Sleep Behavior |
|---|---|---|---|
| - | - | 0 | Disabled |
| 0 | 0 | 1 | Always run in all sleep modes except STANDBY sleep mode |
| 0 | 1 | 1 | Only run in all sleep modes except STANDBY sleep mode if requested by a peripheral. |
| 1 | 0 | 1 | Always run in all sleep mode |
| 1 | 1 | 1 | Only run in all sleep modes if requested by a peripheral. |
When OPAMPCTRLx.ONDEMAND=1, the analog block is powered off for the lowest power consumption if it is not requested.
When requested, a start-up time delay is necessary when the system returns from sleep. The start-up time is depending on the Bias Selection bits in the OPAMP Control x register (OPAMPCTRLx.BIAS) and the corresponding speed/current consumption requirements.