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TPS61230: How to let converter enter PWM?

Part Number: TPS61230

Hello Sir:

Our schematic shows below figure.

Our inductance is 1uH, we make 100pcs products and there were 20pcs in PFM mode.

Please refer our tested waveform in attached file.

Can you let us know how to let converter enter PWM early?

Can we change inductance to 1.5uH?

Please help to provide recommendations for us.

Thanks a lot.

20210830_SW and IOUT waveform.rar

  • Hi Su,

    Thanks for consulting here. Your comments for below questions would be appreciated to solve the issue:

    1.Could you please let me know what is your input voltage (VSYS)?

    2.I assume the load current when issue is witnessed is about 350mA? Could you please confirm here?

    3.Could you please share your layout?

    -Wenhao

  • Hi Su,

    Any comments?

    -Wenhao

  • Hi Wenhao:

    Sorry for late updating. 

    Please refer our feedback as below.

    1. VSYS is 3.4V~4.2V.

    2. Load is an RFID device, which operates current is about 250mA~320mA, when this operation condition which failed rate is about 2%.

    3. Please refer below figure.

    4. We still want to know can we try to increase the inductance? Any side effects? 

    5. Did you think this converter in PFM mode or PWM mode? If in PFM mode how to let it enter PWM, any threshold can be referenced?

    Please help to provide your recommendations.

    Any questions please let us know.

    Thank you very much.

  • Hi Su,

    See my comments below:

    4. We still want to know can we try to increase the inductance? Any side effects? 

    [WW]Increase inductor would decrease threshold entering PFM. The transient may be slower and you may re-evaluate loop stability as RHPZ moves lower by increased inductance;

    5. Did you think this converter in PFM mode or PWM mode? If in PFM mode how to let it enter PWM, any threshold can be referenced?

    Please help to provide your recommendations.

    [WW]See below figure. When inductor valley current is about 200mA, device enters PFM. 

    -Wenhao