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ref3012 output 1.25 to 1.32 in the circuit schematic

Food Sent
Prodigy 20 points
Other Parts Discussed in Thread: REF3012, REF3112, REF3312, REF3212

Vref is ref3012, i need 1.25V output.

when Vin is floating or 0V, ref3012 outputs 1.25V.

when Vin is 3.3V, 5V or 15V,ref3012 output 1.32V.

i want to know whether i use ref3012 right. if ref3012 can't use in the circuit, can you give any advice for Vref.

Thanks very much!

Liang

  • 0
    TI__Guru 60570 points

    Liang,

    REF30xx family including REF3012 can only source output current while its sinking capability is limited to only quiescent current of its output stage (-10uA) - see PDS table and graph below: 0mA < Iout <+25mA.

    For that reason applying Vin voltage above Vref results in erroneous output voltage since to bring the output to its nominal  value of 1.25V, REF3012 would have to sink the current coming from R2 pull-up resistor but it can't.

    We have other voltage references capable of sourcing AND sinking output current - please take a look at REF3112, REF3212, or REF3312.

  • 0 in reply to Marek Lis
    Prodigy 20 points

    Thank you very much. I replace for REF3112, and the circuit works well. The bad news is that our company will collapse.

  • 0 in reply to Food Sent
    TI__Guru 60570 points

    Glad I could help. Good luck.