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TPS7A19: Output Voltage dip issue with the device

Chandrashekhar D R1
Intellectual 270 points
Part Number: TPS7A19

Hi,

Currently we thought of using the TPS7A19 in our design with input voltage in the range of 11 to 28volts with 3.3V output. Our load requirement will be in the range of 150 to 200mA. Will I be able to use this part for this requirement. 

Problem we are facing with this device is output voltage is dropping to 2.45V when my load requirement is 100mA (when the load is 22ohm). Only when my load is less than 10mA then only the device is working fine. Can you please help us in solving this issue.

Thanks,

  • 0
    TI__Intellectual 825 points

    Hi Chandrashekhar,

     To better help you with the issue, could you please share your schematic? 

    What was the measured voltage at the IN pin when the output dropped to 2.45V? maybe the power supply used is clamped to a certain lower current? a scope shot  with Vin and Vout plots would be helpful to see what's going on.

    Looking at your design requirements, you need to consider Thermal (proportional to Power dissipation) in your design. Worse case scenario in your design is when Vin = 28V and Iout=200mA.  

    Power = Vin*Iq + (Vin-Vout) * Iout   (or   approx  Power = (Vin-Vout) * Iout)

    Power = 24.7*200mA = 4.94W

    Thermal rise = Power * thetaJA = 4.94W * 48C/W = 237.12 C

    assuming ambient temperature is 25C, the Device temperature is 25C + 237.12C = 262.12C which is above the maximum temp spec.

      To minimize, power dissipation, you need to minimize (Vin and Vout) delta and/or the load current.

    Regards,

    Chito

  • 0 in reply to Chito Tapia
    TI__Intellectual 825 points

    it seems the Thermal information got lost in my previous response. so here it is.

  • 0 in reply to Chito Tapia
    TI__Intellectual 825 points

    Hi Chandrashekhar,

    Since it has been a week without a reply, I assume that this thread is resolved. If this is not correct, please feel free to post again.

    Regards, Chito