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TPS780330220DRVR Line regulation and line transient response

Rajesh Kaliyaperumal
Intellectual 930 points
Other Parts Discussed in Thread: TPS780

Hello Everyone,

We are using TPS780330220DRVR LDO in our product as a power supply from 5 volts input .Hence I wanted to check the line regulation performance of the device. I have used Webench design for the line transient response where i got the following results corresponding to the input voltage variation of 4.5 volts to 5.5 volts which are contrary to the specification given in the datasheet.

There is a variation in output voltage of 300mV from 3.3 volts when we change the input voltage to 5.5 volts from 4.5 volts.But in your datasheet you have mentioned the line regulation ( for 150mA load current) as 1% where as in our simulation we are getting a load regulation of around (300mV/3300mV *100 = 9 %).

Kindly clarify the above query at the earliest.

Regards,

Rajesh K.

  • 0
    TI__Prodigy 100 points

    Hi Rajesh,

    The line regulation is a DC characteristic, the Vout vs. Vin is generated by a very slow sweep of Vin. Your simulation is a transient response. Based on the timescale, the switching from 4.5V to 5.5V is fast.

    Please check figure 46. from the TPS780 datasheet for the transient response:

     

    Thank you,

    Andrey Volynets

  • 0 in reply to Andrey Volynets
    Intellectual 930 points

    Hi Andrey Volynets,

    Thank you for clarification and I got your point . Basically you are saying to take the settled value after the Line voltage changes instead of looking at the transient response.

    In our case , It has line regulation of (20mV/ 3.30 *100 )  0.6 %  which is good and as per the specification in datasheet.

    Thanks and Regards,

    Rajesh