VSYS pin on nPM1100 integrated Power Management IC

[Avgerinos]

I am designing an application using the nPM1100 and I would like to know if I can use the VSYS as a power supply pin for my other circuit.

Is VSYS supplied by the battery when USB is not connected on nPM1100 integrated Power Management IC?

What is the voltage on VSYS when the USB is disconnected?

Thank you

[Pallav Aggarwal]

There is a plot in the product specification document, you will be able to see how Vsys voltage will be. 

Yes, the power path switch will connect the battery to VSYS when the USB is not connected.

[Avgerinos]

Which Figure is the plot about Vsys that you are talking about?

[Pallav Aggarwal]

Check : https://infocenter.nordicsemi.com/pdf/nPM1100_PS_v1.0.pdf

Page 17, 18,19

[Avgerinos]

I was checking at these figures, but it does not say what happens to vsys when vbus is 0V or disconnected. That is why I am confused about it. It would be useful to see a plot with vsys, vbus and vbat. So it will be clear what happens when vbus is disconnected but there is a voltage on vbat due to the battery, and how the vsys voltage is affected. 

[Amanda Hsieh]

Hi, 

(Updated)

We took some measurements to show this. Please let me know if it doesn’t answer the question.

-Amanda H.

[Avgerinos]

This is great!
Thank you!

[madhu01]

Subject: Using nPM1100 VSYS as Input for LDOs – Current Distribution & Limitations

Hi,

I am using the nPM1100 in my new application, where the system power circuit includes two additional 250mA LDOs configured to provide a 3.3V output. I am also using the DC-DC regulator in the PMIC to generate a 1.8V supply required for my application.

I would like to confirm whether I can use VSYS as the input for these two LDOs. The total system power consumption is expected to be around 250mA to 300mA.

Additionally, when the battery is charging, how will the current distribution be managed between the system load (through the VSYS, 1V8 Buck, and Battery Charging) and battery charging? What is the maximum current output available from VSYS, and is there any priority mechanism between powering the system and charging the battery?

Any special checkpoints or design considerations I should keep in mind for reliable operation?

Thank you!

[Amanda Hsieh]

Hi, Please create a new support case.