AMS-1117 Voltage Regulator Notes

AMS-1117 (5v version)

Current recommended application:

  • Voltage regulation to ~750mA
  • Max input voltage sources:
    • 4x or 6x AA battery pack (6V – 9V) for 5V systems
    • 3x or 4x AA battery pack for 3.3V systems
    • LiPo 2S battery for 5V systems

Max input voltage:

  • 15V (from the datasheet)
  • 12V as assembled / shipped by the pcb manufacturer
  • 10V from others who have tested the part
Failure input voltage: 13.4V, no-load voltage, as tested from a common 7Ah, 12V SLA battery

Possible failure symptoms:

  • Fail open
  • Fail closed / no regulation

Max output current:

  • 1A (from datasheet)
  • 800mA (from pcb manufacturer)
Power supply using this IC is a common eBay part:
Note the two burn marks on the top of the IC.
This is what it looks like when it’s dead.
When I connected power to this board from a 13.4V (12V) lead-acid battery it did NOT survive. Either the current drain was too high; unlikely, as the project was powered from 500mA USB until now, or the voltage was too high. Again, unlikely, as I have 4 batteries and have swapped them around between this and a working project. UPDATE: The other project uses a 3A DC-DC buck converter, not this part. It’s likely this part can’t be used above 10V (for the 5v output variant).
Failure notes:
I’ve investigated if there is a dead short somewhere else that isn’t back-powered from the USB > FTDI > Adruino Pro Mini, and it doesn’t appear so. For the moment I think it’s an IC that died on 13.4V input. The eBay listings for these typically list a lower maximum input voltage of 12V, and other tests show a maximum input of 10V.

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