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TPS715A: Is the reference voltage assumed to be constant across the input range?

Part Number: TPS715A

Figure 7.2 details that the Internal Bandgap Reference produces a typical Vref of 1.205 V, and in programming (section 8.2.2.1.1) that value is used to determine the resistor values for the required Vout. 

Is this value constant across the input voltage range (up to 24 V)? I am assuming so, but since this is only given as a "typical" value and not much other information is given, I wanted to make sure. 

Thank you, and happy holidays! 

  • Hello,

            The DC PSRR of the Error Amplifier will determine the variation of Feedback pin voltage (VREF) with VIN. But for purposes such as to determine the resistor values, this variation can be ignored and the typical value of 1.205V may be used. The variation in VREF can however be deduced from the Line regulation Spec that is provided to be 60mV (Max) at VOUT = 2.8V. Since VOUT is simply a scaled version of VREF, the maximum variation in VREF would then 60mV/2.32 = ~26mV ( since 2.8/1.205 = 2.32), across the appropriate VIN range. Thanks!

    Regards,

    Srikanth