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TLV62565: is there any risk with 10uH inductor in tlv62565 application

Part Number: TLV62565
Other Parts Discussed in Thread: TLV62080

hi,

as output current is between 75mA and  350mA, tlv62565 will enter PFM in which output voltage is 0.9% higher than that of normal mode. it causes image performace issue. with 10uH inductor, tlv62565 works in normal mode always and the issue is disappeared. any risk for 10uH inductor? detailed test report is attached, pls kindly check it and give your comments.issue caused by TLV62565-PFM.pdf

  • using TLV62565 with a 10uH inductor is outside the values we recommend in the datasheet. Such a component combination has therefore not been tested. However, the waveforms you attached look OK to me and I think that the output filter should not cause any instability problems.
    Just make sure to test the application at corner conditions relevant for this design.
  • HI,

    As tlv62565 is internal compensation and no relative parameters listed in DS.Need you help to calculate its loop stability with 10uH inductor.if it can't be calculated out, Is there aother recommended devices simlar with tlv62565 except of PFM? 

  • You can measure the loop with a bode plot to assess stability with your components.

    The TLV62080 uses a different power save mode, which has lower ripple and no intentional Vout change in PFM.
  • Chris
    thanks your replay and suggestions.
    would you like kindly check Q2 listed in test report? it is also repeated as below.
    Q2: From DS. of tlv62565, once tlv62565 leave out DCM, tlv62565 will leave PFM and enter normal mode immediately. Is it right? In actual test, by checking SW waveform to assert which mode tlv62565 is working, it seems that tlv62565 will last for some period to enter normal mode (Vout is still kept at value setting with (1+0.9%) *06). Do you find the same phenomena?
  • Your waveform is not very clear. To see which mode the IC is in, you need to monitor the inductor current. It changes modes once the inductor current reaches 0, but of course, it takes some time for the output voltage to reach the new value.