STANDBY can be entered from ACTIVE, MCU ONLY, or the RETENTION states. In order to stay in the mission state of STANDBY and not enter the hardware state LP_STANDBY the LP_STANDBY_SEL bit must be cleared.

Similar to the RETENTION state the STANDBY state turns off all regulators which power the MCU. Therefore, it is required to select the state, MCU ONLY or ACTIVE, that the STANDBY state returns to.

When the ENABLE pin goes low, the TO_STANDBY sequence is triggered. When the ENABLE pin goes high again, the destination state is dependent upon the STARTUP_DEST bits. For the TPS6594141B, the STARTUP_DEST must be set for the ACTIVE state. The TO_STANDBY sequence is also triggered by the I2C_0 trigger. When triggered from I2C_0 the PMIC can be triggered to return to the ACTIVE state by GPIO4 or the RTC timer or alarm. In this example, I2C_0 trigger is used to enter the STANDBY state and the GPIO4 is used to enter the ACTIVE state.

Write 0x48:0xC3:0x00:0xF7  // LP_STANDBY_SEL=0
Write 0x48:0x7D:0xC0:0x3F  // Mask NSLEEP bits
Write 0x48:0x34:0xC0;0x3F  // Set GPIO4 to WKUP1 (goes to ACTIVE state)
Write 0x48:0x64:0x08:0xF7  // clear interrupt of GPIO4
Write 0x48:0x4F:0x00:0xF7  // unmask interrupt for GPIO4 falling edge
Write 0x48:0x85:0x01:0xFE  // set I2C_0 trigger, trigger TO_STANDBY sequence
After the GPIO4 has gone low and the PMICs have returned to the ACTIVE state
Write 0x48:0x7D:0x00:0x3F  // unmask NSLEEP bits
Write 0x48:0x86:0x03:0xFC  // Set NSLEEPx bits for ACTIVE state
Write 0x48:0x64:0x08:0xF7  // clear interrupt of GPIO4