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TPS65100 VOUT3 (Vgh) with AVDD = 10.4 Vdc.

Fred Sauer
Prodigy 100 points
Other Parts Discussed in Thread: TPS65100

I have a TPS65100 with AVDD = 10.4 Vdc.  I would like VOUT3 to be 16.0 Vdc.  The feedback resistors are 640k and 52.3k.  My measured VOUT3 is = 22.4 Vdc.  If I set the TPS65100 to voltage 3x mode vs. 2x mode VOUT = 33 Vdc.   Can VOUT3 be a voltage less than the voltage double voltage?  - Fred

 

  • 0
    TI__Guru 65610 points

    Hello Fred,

    To be honest, I am surprised that you observe a voltage that is higher than 2*AVDD when the IC is set to 2* mode. Normally it is around 0.5V to 1V less than 2*AVDD when the IC does not regulate to a lower voltage.

    In 2* mode the voltage will always be lower than 2* AVDD because of the losses in the internal switches. Is there possibly as well higher voltage on AVDD than expected?

    The feedback resistors are set for 16V, could you measure the voltage on the FB3 node with respect to the IC GND pin?

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 100 points

    Good Morning -  Thanks for the reply.  Below are measured values with refernce to the pcb ground plane. 

     

    V33 = 3.286V

    AVDD = 10.58V

    VGL = -7.19V

    VGH = 21.22V

    FB3 = 0.002V

    I see the odd voltage at FB3.  I measured between pin 12 and ground, etc. and did not measure a short.  I checked the simple circuit traces to the feedback resistors.

    - Fred

  • 0 in reply to Fred Sauer
    Prodigy 100 points

    Rookie Mistake.  Tested the new values on a production intent board and it appears to be working.  To many leads and probes on the dev unit.

    V33 = 3.30

    AVDD = 10.63

    VGH = 16.67

    VCOM = 4.13

    FB3 = 1.251

    FB2 = -0.044

    VGL = -7.10