enough current to power peripheral?

The official pyboard running MicroPython.
This is the reference design and main target board for MicroPython.
You can buy one at the store.
Target audience: Users with a pyboard.
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ldbm
Posts: 14
Joined: Thu Apr 04, 2019 2:48 pm

enough current to power peripheral?

Post by ldbm » Mon May 18, 2020 8:18 pm

Hi,
I am trying to figure out if I can power a peripheral with Pyboard v1.1 V+ pin used as an output.

The external chip requires 3.3V to 5.2V . Normal current draw would be modest, around 20-40mA, but it would briefly spike to 600-800mA. (briefly may be ~ 1 s or less) . I was thinking to power Pyb via the microUSB ( just using the power lines) with a battery. I would have to account for the drop in D1 though, which for this current would be ~ 1V (see specs). The battery being 3.6 V Nominal, this would lead to 2.6V left at V+: not good. Plus there would be no regulated voltage with this approach...

Same issue on the Pyboard D it seems with the LD39130S LDO rated for 300mA :(

L.

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Roberthh
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Location: Rhineland, Europe

Re: enough current to power peripheral?

Post by Roberthh » Tue May 19, 2020 6:37 am

You can supply the Pyboard through the V+ signal. The voltage range is 3.6-16V. Then you can attach the external device too at these pins.

ldbm
Posts: 14
Joined: Thu Apr 04, 2019 2:48 pm

Re: enough current to power peripheral?

Post by ldbm » Tue May 19, 2020 5:11 pm

Thx Robert. Yes like you say why not just powering the peripheral with the external source powering the board.

PS: the doc page points to LDO MCP1802 (up to 10 V supply) and omits the link to the MCP1703 on the Pyboard 1.1 (up to 16 V supply like you mention)

ldbm
Posts: 14
Joined: Thu Apr 04, 2019 2:48 pm

Re: enough current to power peripheral?

Post by ldbm » Tue May 19, 2020 6:28 pm

Actually, this micropython official pagehas misleading info about powering the boards: pyb v1.0 can only be powered up to 10 V as they use the LDO MCP1802 . Unless I am missing something (newbie using this board).
Cheers,
L.

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