Hi there,
I've designed a custom board implementing the nPM1300 and am currently in the process of examining the board without any firmware. Throughout testing, I have tried to power on the board using VBUS and VBAT.
The issue I am facing is:
- The output of VSYS and VOUT1/VOUT2 are correct when powering directly through VBAT using a power supply set at 3.7V. The current draw of the system sits at around 30 mA.
- The output of VSYS is incorrect (approx. 2V) when powered directly through VBUS using a power supply set at 5V. The current draw of the system is 0-0.5 mA.
- This causes the output of VOUT1/VOUT2 and an external buck regulator that I have connected to VSYS to be incorrect.
- The only additional connection to VBUS apart from the nPM1300 VBUS input is an ESD protection diode.
- I have also tried powering through VBUS using a USB cable connected to a power bank and laptop. When using the power bank, it delivers 5.15V into VBUS for around 20 seconds before dropping to around 2V.
Is this a hardware or firmware issue? I understand that there are some functions that can only be programmed through firmware, however I was under the assumption that the buck regulators and basic functionality (including being powered through VBUS) were possible without any firmware commands.
Thank you!
