Blue pill current?

Generic boards that are not Maple or Maple mini clones, and don't contain the additional USB reset hardware
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turboscrew
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Blue pill current?

Post by turboscrew » Thu Jul 27, 2017 9:19 am

Does anyone happen to know how much current the on-board 3.3V regulator can supply?
I'm trying to put together a small 433MHz network. I wrote some kind of scanner using a CC1101-based small radio module, and I was wondering whether it's safe to feed that (blue pill + radio module) with a 5V USB serial dongle through the blue pill's on-board regulator while developing a node.
Then I could test both the node and the scanner.

I wrote the scanner to find out communication parameters of a 433 MHz USB radio dongle, but I think my dongle was really DOA.
I ordered a new dongle - a bigger and better (I hope), but it hasn't arrived yet, and probably won't arrive any time soon.

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Pito
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Re: Blue pill current?

Post by Pito » Thu Jul 27, 2017 9:32 am

RT9193-33 - 300mA max (thermal shutdown at 165deg Celsius in BPill)
http://www.richtek.com/assets/product_f ... 193-16.pdf

Mind the absolute max power dissipation for that regulator in BluePill's sot-23-5 package at 25deg ambient is 400mW.
With 5V input it means the absolute max Iout is

Iout = 0.4W / (5V-3.3V) = 0.235A = 235mA <--- That is Absolute MAX current at which the chip inside will have temperature 125deg Celsius

(see pages 8 - 9 of the datasheet)

So I would go max 100mA..


PS: You have to look at the BP's schematics (ie from our wiki). You will see the part number of the voltage regulator. You put the number into google. You get the datasheet and you read the information on max current..
Last edited by Pito on Thu Jul 27, 2017 10:32 am, edited 6 times in total.
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RogerClark
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Re: Blue pill current?

Post by RogerClark » Thu Jul 27, 2017 10:10 am

The regulators on the BluePill are generally low quality and don't perform to the spec

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Pito
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Re: Blue pill current?

Post by Pito » Thu Jul 27, 2017 10:18 am

It could happen they perform according to the spec in datasheet - see above - but the chip is very low power basically..
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turboscrew
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Re: Blue pill current?

Post by turboscrew » Thu Jul 27, 2017 10:39 am

I don't know which schematics to look into - there is no sign of any manufacturer. I took a microscope shot from the chip, though, and it says "DE=A1D" on the top. I guess it's RT9193-33GB. Thanks a heap!

I guess it's better NOT to use the on-board internal regulator.

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Pito
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Re: Blue pill current?

Post by Pito » Thu Jul 27, 2017 10:42 am

turboscrew wrote:
Thu Jul 27, 2017 10:39 am
I don't know which schematics to look into..
BPill
http://wiki.stm32duino.com/images/c/c1/ ... ematic.pdf
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turboscrew
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Re: Blue pill current?

Post by turboscrew » Thu Jul 27, 2017 1:24 pm

Pito wrote:
Thu Jul 27, 2017 10:42 am
turboscrew wrote:
Thu Jul 27, 2017 10:39 am
I don't know which schematics to look into..
BPill
http://wiki.stm32duino.com/images/c/c1/ ... ematic.pdf
I understand that different manufacturers can use different components. A friend of mine has some bluepills with totally wrong RTC crystals.
On his boards, the RTC doesn't work at all with crystal.

dannyf
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Re: Blue pill current?

Post by dannyf » Sun Jul 30, 2017 12:05 am

LF crystals generally have a hard time get it going on the f1.

The drive level is too low for some crystals. The price you pay for claiming low current consumption.

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