Issue of Queue overflow for nPM1304

[Tom.Fu]

Hi Support Team 

We met an issue of Queue overflow for nPM1304 EK like the following screenshot when VBUS_PMIC connect the solar cell? Many thanks.

[Tharaka]

Hi

Queue overflow refers to a message queue that can overflow, typically when many events occur simultaneously.
This may be due to for ex.  stream of charge cycle events (CC, CV, Trickle), which trigger a lots of number of interrupt handling routines, in this case when its connected to a PV cell.

You can also use Record Events option in PowerUP to log such events to see whats really happening behind. 

Regards,

Tharaka

[Tom.Fu]

Hi Support Team 

The battery nPM1304 charge is Li-ion battery of 3.7V, 23mAh and the power supply for the VBUS of nPM1304 is 4V and hundreds of μA, in this case, the issue of Queue overflow reproduce. We think the current for VBUS is too low. What is the minimum voltage and current required for VBUS? Many thanks.

[Tharaka]

Hi

There are 2 conditions for the SYSREG — System regulator block to operate, and so for the battery charging to occur : 

• VBUS > VBAT+150mV
• VBUS > 3.6V 

There is also an undervoltage comparator whch has a ~400mV Hysteresis. This means VBUS has to go above 4.0V to be able to charge and then it can go down to 3.6V.

There is also IQ close to 2mA (VBUS current consumption). 

nPM1304 charger is not meant for such low power/voltage energy harvesting implementations. 

Regards 

Tharaka