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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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