nPM2100 Behavior with LDO in Ultra-Low-Power Mode

[bdub94]

I have a couple of questions regarding the operation of the nPM2100 when using the LDO in Ultra-Low Power (ULP) mode, both in active and hibernate states.

1. Active Mode with Boost in Auto, LDO in ULP:

   • Let’s assume the device is in active mode, the boost is in auto mode, and the LDO is configured in ultra-low-power mode. A small load is connected to the LDO output.

   • According to the electrical specification (Table 12, datasheet v1.0), the maximum output current for the LDO in ULP mode is 2 mA.

   • My question: if the load exceeds 2 mA, what is the expected behavior? Will the LDO output simply droop, or does the device employ any form of current limiting/shutdown behavior?

2. Hibernate Mode with Boost in ULP and LDO in ULP:

   • Now consider the device in hibernate mode, where the boost is forced into ultra-low-power operation. The LDO is configured to remain enabled (in ULP) with a small load connected at its output.

   • If this load exceeds the LDO’s maximum output current in this condition, what happens? Will we just see droop on the LDO output? Could this cause droop on VINT, given that the boost is constrained in ULP mode?

[Menon]

Hello,

1. LDO auto mode means that the LDO operation mode follows the PMIC operation mode, not the load. If auto mode is selected, the LDO will be in HP mode when the nPM2100 is in the active state, and in ULP mode when it is in hibernate state. Therefore, the LDO operation mode will be ULP in hibernate state. Note that the LDO quiescent current from the battery in HP mode is 1.9 mA, so you will want to minimize the time spent in this mode.
2. By “drain the VOUT”, do you mean “shut down the VOUT”? That is not possible. The internal load switch between VINT and VOUT is controlled by a state machine, and there are no user controls for it.

Kind Regards,

Abhijith