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TPS53015: No output for 3.3V application

Webber Chang
Prodigy 70 points
Part Number: TPS53015

Hi, 

The attached pdf is the schematic for the 3.3V output application.

My problem is no output, I had to do some troubleshooting below, but it's still not working,

1. Ensured the output(VDD_3V3_SYS) doesn't short to GND or the other net.

2. Removed R29 and C26.

3. BUCK_3V3_EN is a DC 3.3V signal.

4. Increase the OCP by chang the R25 to 56K ohm.

5. Chang the L6 to 2.2uH(IDC is 3.7A/ DCR is 4.7m ohm)

I have also attached the DRVH & DRVL waveform for your reference.

The DRVH keeps low and DRVL keeps 5V after a while. 

Could you help to figure out what the problem is?

TPS53015 schematic.pdf

Sincerely

webber

  • +1
    TI__Expert 3695 points

    Hi Webber,

    Thank you for sharing the schematic and waveforms. I have looked at them and have some follow up questions and feedback below.

    Looks like this occurring due to the large amounts of noise. I see that the DRVH has no gate resistor in the path to the FET's gate. I suggest that you add a 10 Ohm gate resistor as it will limit the current and should reduce the noise significantly. I would also suggest to add a 2.05 Ohm resistor in series with the SW pin for the same reason. Also add a 1KOhm resistor in series with the EN pin to limit the current inrush. Finally, I would also suggest to use a 5Ohm resistor for the bootstrap capacitor. Large dv/dt spikes can cause high-side FET oscillation or supply overshoot. Look here to understand the implications of bootstrap dV/dt.

    Looking at the waveform, there is a lot of noise in your measurement. Can you explain how you are probing and what the bandwidth limit is?

    What input voltage, output voltage are you using?

    After making these changes, can you send a screen capture of your waveform with DRVH, DRVL and SW pins together.

    Regards,

    Akshat

  • 0
    Prodigy 70 points

    Hi Akshat,

    Thanks for your suggestion. It's helpful to me.

    I found out the root cause, and a leakage voltage affects the output(VDD_3V3_SYS then triggers TPS53015's OVP).

    TPS53015 works properly after addressing the leakage voltage.

    Sincerely

    Webber

  • 0 in reply to Webber Chang
    TI__Expert 3695 points

    Hi Webber,

    That's great to hear! Let me know if you have further questions.

    Regards,

    Akshat