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REG103 5V

Jon Saul
Prodigy 10 points

Attempting to use 103fa-5, DDPAK5 version.

Pin 1 - 9VDC battery input. 9.8 VDC measured at pin 1

Pin 2 - 3VDC battery. 2.8VDC measured at pin 2. Appears enable pin works as I can remove this voltage  and out is 0 VDC

Pin 3 - GND

Pin 4 not used

No loads

here's my problem

When pin 2 enabled, pin 5 (output) always at 2.1 VDC instead of 5VDC.  Why? How do I get 5 VDC out of this 5 VDC regulator?

I used all three TI samples and get the same result

 

All pins are isolated except for pin 3 (gnd) and pin 5 (output) which have 78K - 94K ohms depending on which REG 103 I test.

 

Thanks inadvance for any help

  • 0
    TI__Mastermind 41770 points

    Hi Jon,

    I have a couple of comments and questions. Are you measuring the output with an o-scope? Is the output oscillating? I know all pins are isolated and the load is small but could there possibly be a short somewhere on the board thats causing the device to go under current limit? You may want to check the connections for any kind of short or make sure the input power supply is not current limiting. Lastly, please check the connection of the ground pin. It may be that there is not a solid ground connection of the IC and the external components that's causing a degraded measurement.

    Regards,

    Darwin