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TPS7B86-Q1: Need to confirm KVU package different dropout for ADJ and FIX version.

Kuno Wu
Prodigy 80 points
Part Number: TPS7B86-Q1

Hi Team,

We are using the TPS7B86-Q1 KVU package, and we need the ADJ and Fixed version. When we check their dropout difference, we find the test result are not match with the datasheet show. Based on the datasheet, the Fixed version have a smaller dropout voltage, but from my test result, the ADJ version is better, do you know why?

Best Regards,

Kunyue

  • 0
    TI__Expert 6570 points

    Hi Kunyue, 

    The adjustable version of this device has a lower Vin minimum. 

    BR,

    Erin

  • 0 in reply to Erin Thibeault
    Prodigy 80 points

    Hi Erin,

    Yes, but my confusion is that for the KVU dropout voltage, ADJ version is better or Fixed version is better?

    Best Regards,

    Kunyue

  • 0 in reply to Kuno Wu
    TI__Mastermind 37075 points

    Hi Kunyue,

    One possible reason that the dropout voltage you measure can be different than the datasheet values is your measurement location. 

    An adjustable LDO's "point of regulation" - or location where the voltage is being regulated at - is where Vout meets the top setpoint resistor with respect to the LDO GND pin.  So you should measure the dropout while probing the output voltage at the top setpoint resistor and GND at the LDO GND pin.

    With a fixed LDO, unless the device has a sense pin, you would probe the output pin (instead of a setpoint resistor pin) and the GND of the LDO.

    Anywhere else on the PCB can cause error in the measurement.

    Thanks,

    Stephen