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Have i received a faulty IC ?

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IamSynthetiC:
Greetings,

I recently received a pre-made prototype-board (Power Supply) from PCBWay and the -12V rail does not work properly. The Linear Voltage Regulator (TPS7A3301RGWR) outpouts -14.86V instead of -12. Curiously the TSP7A33 is receiving -14.86V, and there seems to be no Voltage Dropout.

I found other people having similar problems and complaining to TI's forum about this IC, but the solutions (if there are any) where not published.
I would like to get a second opinion before i contact PCBway or TI, and potentionaly embarrass myself  ;D .

Thanks for your time.

Link to EasyEDA project

*Edit : Fixed values.

langwadt:

--- Quote from: IamSynthetiC on August 12, 2020, 10:36:21 pm ---Greetings,

I recently received a pre-made prototype-board (Power Supply) from PCBWay and the -12V rail does not work properly. The Linear Voltage Regulator (TPS7A3301RGWR) outpouts 14.86V instead of -12. Curiously the TSP7A33 is receiving 14.86V, and there seems to be no Voltage Dropout.

I found other people having similar problems and complaining to TI's forum about this IC, but the solutions (if there are any) where not published.
I would like to get a second opinion before i contact PCBway or TI, and potentionaly embarrass myself  ;D .

Thanks for your time.

Link to EasyEDA project

--- End quote ---


sense not connected? what is the voltage at FB?

Phoenix:
Is this a board of your design? I just want to make sure you are feeding the regulator -14.86V instead of +14.86V...

IamSynthetiC:
Oups, i forgot about the "-" in the values, i fixed it.

This is indead my own design, but i have tried to follow the datasheets guidelines to the letter. The -12V rail is the only one not working.

As for the voltage at the FB pin, measured at the C8 cap, it was -33uV when disconected from Vout. I found no shorts to ground.
When connected to Vout, the voltage darectly at the Sense pin is as -14.86V, but at the Sense side of the R6 resistor is -29uV. And the C* cap remains at -33uV.


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