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TPS7B70-Q1: Line Transient Figures

ReedKacz
Expert 3462 points
Part Number: TPS7B70-Q1

Hello Team!

Figures 17 and 18 in the datasheet are labeled as line transients from 6V to 40V and 40V to 6V. Looking at the VIN plot it is actually 9V to 16V and 16V to 9V. Could you please share updated plots for the 200mA load, line transient testing for 6V to 40V and 40V to 6V?

Thanks-Reed

  • 0
    TI__Expert 5231 points

    Hi Reed,

    Thank you for your question. I looked through our documentation and there seems to be an error in our data sheet. I will go down to the lab and complete the test for you.

    Thank you,

    Josh Nachassi 

  • 0 in reply to Josh Nachassi
    TI__Expert 3462 points

    Josh - thank you, I look forward to the updated plots. 

  • 0 in reply to ReedKacz
    TI__Expert 5231 points

    Hi Reed,

    I will get those plots to you tomorrow. 

    Thank you,

    Josh Nachassi 

  • 0 in reply to Josh Nachassi
    TI__Expert 5231 points

    Hi Reed,

    Hope all is well. I have attached the scope shot from my line transient test with 200 mA of current. Please let me know if you have any questions.

    Thank you,

    Josh Nachassi

  • 0 in reply to Josh Nachassi
    TI__Expert 3462 points

    Hi Josh - thanks for sharing. I am surprised how large the droop is on the falling edge ~600mV. Can you help in explaining why we are seeing >12% of the output droop on a 5V LDO?

  • 0 in reply to ReedKacz
    TI__Expert 5231 points

    Hi Reed,

    Yes, I was surprised as well in the change of response. 

    Before I ran this test, I wanted to replicate the 10-V to 15-V rising and falling edge as it's shown in the data sheet, and I was able to replicate it with great precision.

    Output capacitors and output current didn't affect the transients that much in my bench tests but the change of voltage from 6-V to 40-V is what really effected it. Also notice that it takes about 20 us to go back to normal regulation after the AC transient response happens which is great.  

    I was going over my results with a colleague and we noticed that there is a rapid increase in the start of the falling edge of my signal as opposed to the smooth curved end of my rising edge. I will try to increase my falling edge time and see if the transient responds better. I will update you.

    Please let me know if you have any further questions.

    Thank you,

    Josh Nachassi 

  • +1 in reply to Josh Nachassi
    TI__Expert 5231 points

    Hi Reed,

    Here is the scope shot when I increased my falling edge time to 42 us which is around what the data sheet has it to and my transient response is around 300 mV. If I increase the time further, my transient response gets much better. 

    Please let me know if you have futher questions. 

    Thank you,

    Josh Nachassi