The AC_DET pin is a CMOS-type input used in three different ways to control the power-up of the PMIC:

• In a battery operated system, AC_DET is typically connected to an external battery charger with an open-drain power-good output pulled low when a valid charger supply is connected to the system. A falling edge on the AC_DET pin causes the PMIC to power up.
• In a non-portable system, the AC_DET pin may be shorted to ground and the device powers up whenever system power is applied to the chip.
• If none of the above behaviors are desired, AC_DET may be tied to system power (IN_BIAS). Power-up is then controlled through the push-button input or PWR_EN input.

A. Portable Systems

B. Non-portable Systems

C. Disabled

Figure 7-20 AC_DET Pin Configurations

Figure 7-21 AC_DET Input Deglitch and Power-Up Timing (Portable Systems)

In ACTIVE state, the TPS6521855 monitors the AC_DET input and issues an interrupt when the pin status changes, such as when it drops below or rises above the AC_DET input-low or input-high thresholds. The interrupt is masked by the ACM bit in the INT_MASK1 register.

Figure 7-22 AC_STATE Pin