nPM1300 battery charge + USB host functionality and power delivery for non-charger USB devices

[whati001]

Hi All,

I am currently evaluating how I can charge a single cell with the nPM1300 PMIC with a USB-C connector, with the addition that the same USB-C connector should be also use for connecting USB devices/peripherals when not connected to a charger.

Meaning, the VBUS pin from the USB-C should deliver power to the battery when connected to an charger and should deliver power from the battery to the external connected USB device. So far, I understand that I can use the nPM1300 PMIC for charging the battery and powering the system. But how can I change the roles? Such that I can connect an external device to the USB-C and that the PMIC provides 5V to the VBUS PIN?

I have found the following blog post, unfortunately, it only explains how to use the PMIC without an USB connection:

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/extend-battery-life-and-add-usb-c-charging-with-the-npm1300?CommentSortBy=CreatedDate&CommentSortOrder=Ascending

Thanks in advice.

[Hieu]

Hi whati001,

This is done on the Thingy:91 X. You can reference its design.

Hieu

[whati001]

Hi Hieu,

thank you very much for your feedback. I took a look at the hardware files at the thingy 91X but seem to be too stupid to understand how the thingy can provide power to an external connected USB-C device.

So I have illustrated the two use cases one more time below in case my explanation was bad.

I fully understand `Usecase 1`, the nPM1300 does the USB-C addressing via the CC lines and sinks the power from the charger through the VBAT pin.

But how `Usecase 2` work? What I am not getting is that in my opinion, either the nPM1300 or the nrf5340 have to source the VBAT pin of the USB connect J6. 

The only possibility I see is that the nPM1300 reverts the VBUSOUT and VBUS path, which is not possible based on the nPM1300 manua: https://docs-be.nordicsemi.com/bundle/ps_npm1300/page/nPM1300_PS_v1.2.pdf?_LANG=enus

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So, I think I am trying to achieve something which is simply not possible with the Thingy91X. Based on this ticket, the nrf5340 (to which the USB lines D+/D-) are connected, does not support USB host mode.  Can the nRF5340 act as a USB host? 

But if I would use a CPU which supports USB Host mode, does the nPM1300 would support Usecase 2?

[Hieu]

Hi whati001,

My apology. I missed the requirement that your device needs to be able to supply power to other devices via the same USB port.

Since it might be relevant, may I ask whether you are using a nRF MCU for this system or not?

And what voltage is your MCU running at? Can it be 5V?

[whati001]

Hi Hieu,

no worries, I am happy that we are on the same page.

No, the MCU would not be from you, but how does this matter?

The MCU will run at 3.3/3.6V.

[Hieu]

Hi Andreas,

whati001 said:

No, the MCU would not be from you, but how does this matter?

No problem at all. It's just most nRF devices can run on 5V, and, if I remember correctly, some have an external voltage out pin, which might help here.

As for the main design issue, you mentioned "power delivery" in the opening post. Do you mean USB-PD? If you plan to support USB-PD, then the supplied device will have negotiation over the CC lines, which are connected to the nPM1300, and I think the nPM1300 likely doesn't support that.

If it's not USB-PD and you just want 5V supply on the VBUS and GND, then perhaps it would work with the VOUT of the nPM1300 after a boost regulator. I will have to leave further recommendations to a colleague with more hardware knowledge though.

Unfortunately, most of them are on vacation and I couldn't find help today. I am out of office myself from Monday, but I will transfer this case to my team, and they will find someone with better expertise to take over.