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TPS62130: Inductor for switching sometimes making noise.

Vivek Kumar14
Prodigy 20 points
Part Number: TPS62130
Other Parts Discussed in Thread: TPS22810, TPS62135, TPS62147

Hello everyone,

I have a power management circuit, in which the main regulation is done by TPS62130 switching regulator. It converts upto 8.4v of DC supply from a Li-Ion battery pack to 3.7V. Switching frequency is 2.5Mhz. 
Here is the schematic of the supporting circuit.

Here are the waveforms at SW pins. 

The operation of this circuit is quite smooth overall and I am satisfied with the performance. However, there are a very rare occasions where the inductor (L601) makes a faint high frequency humming noise. Inductor's part no.: 74404043022A (2.2µH Shielded Wirewound Inductor 3.83A 23 mOhm).

This circuit is used to power a GSM module through a load switch (TPS22810) along with other ICs and peripherals.

Can you please tell what could be the reason for this observation? And how do we rectify it?

Thank you.

Regards,

Vivek

  • 0
    TI__Guru**** 150950 points
    Hi Vivek,

    With 3A device like TPS62130, you need a higher saturation current inductor. The 3.83A is the temperature rating, but that one only has a 2.28A saturation current rating. Looking at its D/S, it saturates very hard. For loads above ~2A, it will have a much lower inductance. This may be the cause of the noise.

    We also have the newer, smaller, more accurate 4A TPS62135/6 and 2A TPS62147/8.
  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Hi Chris,

    Thank you for the reply. I haven't tested with a higher saturation current rated inductor but i think it might just work. I will select one of the inductors from web bench design which generally seem to have very high saturation current rating.

    Best regards,

    Vivek