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We are developing a low-power peripheral and have noticed that USB batteries seem to shut off when non-PD consumption drops below some threshold (e.g. 50 mA) for some period of time (e.g. a few seconds). However, when in PD mode the same batteries seems to stay awake down to an arbitrarily low supply. This got me to thinking that maybe PD is somewhat better all around. Is it better to use PD if possible, even if the higher power isn't needed?

Jeff
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  • USB PD is way better than any other USB power protocol, but it has its complexity toll. – fraxinus Dec 26 '22 at 18:11
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    Better depends on what you value, so it is opinion-based. – Justme Dec 26 '22 at 18:37
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    A workaround could be to load the Powerbank with 80-100mA to reset the shutdown off timer, example https://technoreview85.com/how-to-stop-a-power-bank-from-turning-off/ – MatsK Dec 26 '22 at 18:43
  • Thanks @MatsK this was actually our plan until I discovered that PD seems to work as well (as long as the battery supports PD). Now I’m trying to decide the best approach. – Jeff Dec 27 '22 at 01:41
  • @Justme I feel like I gave a good example of what might constitute "better". I'm looking to see if my thinking is correct and if there are any other benefits. – Jeff Dec 27 '22 at 20:49
  • @Jeff Well, USB power banks (they are not batteries) are not meant to power arbitrary loads. Their main purpose as a specialized device is to charge something like a phone and turn off when charge is complete, to save enery. Some USB power banks may stay on forever, but they will consume energy by being on. Perhaps you should consider integrating a battery instead of relying on features (or the lack of them) of USB power banks? – Justme Dec 27 '22 at 21:09
  • @justme actually my understanding is that USB-C is a cold connection, so power banks should be able to stay on and consume < 1uA. Anyway, for our use case, power banks are very attractive and it’s worth the hassle to get them working. – Jeff Dec 28 '22 at 14:28
  • And you know about "pass through"? Som USB powerbanks can be charged while delivering power and some can't. – MatsK Dec 29 '22 at 19:06

1 Answers1

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A workaround could be to load the Powerbank with 80-100mA to reset the shutdown-timer.

But in the circuit below would I change the 33ohm to 47 ohm that would put the load closer to 100mA.

33 Och (130mA) + LED (11mA) = 141mA load
47 Och (91mA) + LED (11mA) = 102mA load

Ref.: https://technoreview85.com/how-to-stop-a-power-bank-from-turning-off/ enter image description here

MatsK
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  • That's pretty close to our current design, I'm mostly wondering if PD is a "better" approach - one issue is that different batteries seem to have different sleep conditions so it's hard to come up with a one-size-fits-all design. – Jeff Dec 27 '22 at 19:49
  • Its a quick and dirty solution that is cheap and by varying rhe 33ohm resistor its adaptable. – MatsK Dec 28 '22 at 10:21