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maximum current on AMP+ 5V

Georg Salentinig

December 01, 2015 08:30

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I just bought an AMP+ and the recommended 18V/60W Meanwell power supply.

I plan to use the AMP+ on a Pi 2 (already works) together with the official 7" touchscreen (will arrive in the next days). RaspiTV measured the display at 2.25W (450mA).

-- Is it save to run the display from the AMP+ 5V power rail?

-- Is it wise to do so? (i.e. I'd call it unwise to do so if the AMP+ uses a linear regulator ... in that case I'd hook a step down converter directly to 18V)

I don't want to risk the AMP+ (I love the sound of it ... it's awesome and exactly what I needed ... thanks).

If I get the ok I will try it out and report back ;)

Cheers

Georg

-------------------------------------------------------

I already posted this question as reply in ... however: that seems to give it a poor rating.

Amp+: How much power is provided to the Pi?

In 5V power rail 

you state that the AMPs power supply can provide 700-1000mA ... this is slightly to vague for me.

 

 

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4 comments

• 0
  
  HiFiBerry team December 01, 2015 12:16

  Hi Georg,

  there is no exact value we can give. It depends on a lot of parameters. Input voltage is one of them. The higher the input voltage the lower the current the onboard regulator of the Amp can provide. You won't destroy the Amp when you draw more current, but the system might become unstable. Therefore, you can just try and see if the system is still running stable. You can also decrease the operating voltage to 12V.

  Best regards
  Daniel

• 0
  
  Olle April 25, 2017 18:16

  Hey Daniel and Georg,

  I was wondering if there is any way to increase the power leading to the Pi. If I understand it correctly, the power supply to the Pi is limited by the capacity of the LMR12010 step down regulator (max = 1A)

  I'm using a USD devise (RTL-SDR dongle) that seems to draw more then is provided by the USB port. Off course it would be possible to use powered USB hub but the project really limits space. 

  Would it be extremely unwise to unsolder the LMR12010 and replace it with something that can provide more current? Is the LMR12010 connected to any vital components other then the ones used to regulate the LMR itself? Can I find a schematic of the AMP somewhere?

  Thanks for helping out!

  Olle

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  Georg Salentinig April 29, 2017 19:31

  Hi Olle,

  I cannot help with information nor advice on the AMP+ onboard voltage regulator.

  But I can post my experience on the power supply of the AMP+/RPi2/official RPi 7" touch display:

  In order to avoid any stability issues and assuming the worst case (700mA from the AMP - 450mA for the display => 250mA left for the Pi .... far too little!) I decided to power the display from an extra voltage regulator.

  For this task I use a Traco TSRN 1-2450 (1A step down regulator; pin compatible to the 7505) powered directly from the 18V supplied to the AMP+. This setup has been running stable ever since.

  This was easy for the display - Getting the power to your USB device is more tricky - You could try with an USB adapter/extension, where you cut the +5V line to insert the extra regulators output.

  Kind regards

  Georg

• 0
  
  Olle April 30, 2017 19:41

  Hey Georg,

  Thanks for your reply anyway. The regulator looks nice and small.
  I wonder what would happen if I just connect the 5v output form the Traco TSRN 1-2450 (or something similar) to the 5v pin (GPIO 2 or 4) op the Pi. Basically ending up with two parallel voltage regulators. Not sure if this is going to cause much disturbance, or stop the Traco or LMR from working. @Daniel, do you have any thoughts on this?

  Kind regards, Olle