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TPS7A39: TPS7A3901 output FFT check.

Kazuya Nakai59
Guru 21595 points
Part Number: TPS7A39

 Hello guys,

 One of my customers is evaluating TPS7A3901 for their next products.

 They checked the output of TPS7A3901 with FFT.

 Then they found the output peak frequency was around 940kHz.

 Do you think their FFT result is correct?

 Your reply would be much appreciated.

 Best regards,

 Kazuya.

  • 0
    TI__Mastermind 23361 points

    Hi Kazuya, 

    The resolution from the scope FFT may not effectively pick up the noise generated by the LDO. You may refer to Figure 18 - 23 in the datasheet for LDO's noise performance and check if the sope is able to pick up the noise power at that amplitude. 

    The spike at  940KHz does not seem to come from the LDO and if it was, the spike will also show up in the datasheet noise figures.

    Regards, 
    Jason Song