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TPS65131 - Variable Dual Vout(Vpos/Vneg) controlled by AMC7812B DACs

Masaharu Katayama
Expert 1420 points
Other Parts Discussed in Thread: TPS65131, AMC7812B

Dear Sir,

I am designing dual Vout (Vpos and Vneg) using TPS65131.

The desig requires to vary each Vout voltage range as follows;

VPOS :  3V to 15V

VNEG: 0V to -15V

controoled by DAC analog outout (use AMC7812B).  

The method is to feed current and connect the DAC outs to FBP and FBN pins through resistance (named RDAC0/RDAC1). I am attaching an simple block diagaram and calculations.

AMC7812B DAC output will have 0 to 5V full scale voltage swing range.

7142.TPS65131 Unveral Vout.pdf

May I get your review if this will work?

I would appreciate for your advaice.

Best regards,

Masa 

 

  • 0
    TI__Intellectual 1065 points

    Masa,

    In theory, I think what you propose should work, however, RDAC1 would need to be connected to FBN, not VNEG as shown in your diagram. Unfortunately, your desired voltage ranges will not be achievable. The TPS65131 needs a minimum VIN of 2.7 V and the minimum VPOS that can be generated is VIN + 0.5 V (i.e. 3.2 V). You don't say what VIN you're proposing to use, but it needs to be higher than 2.7 V for reliable operation, and VPOS will be correspondingly higher. The maximum VNEG the TPS65131 can generate is –2 V.

    Regards,

    Nigel Smith

  • 0 in reply to Nigel
    Expert 1420 points

    Hi Nigel,

    Thank you very much of your advice. Yes, I mistook the FBN connection. I understand the min VPOS and max VNEG at Vin = min 2.7V which my require higher Vin for stable operation.

    Best regards,

    Masa