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TPS65320-Q1: The Buck Output shutdown

Part Number: TPS65320-Q1
Other Parts Discussed in Thread: UCC21530-Q1

Hi There, 

My customer is using TPS65320-Q1 and below is the schematic. 

The problem is that the 5V output (Buck output) in shutdown during the operation. The buck output is connect to 2 pcs of UCC21530-Q1 as the biased power supple which the current is lower than the OCP threshold of Buck Regulator. 

I'd like to point out that customer using the Buck output as the LDO enable (EN2), Is that could be the reason of this abnormal behavior? 

Thank you for the support!

Best Regards,

Pin

  • Hi Pin,

    I don't see any issue from the schematics and using the Buck output as the LDO enable (EN2). Would you please share some waveform captures from the issue? I need to see what's going on with the P12V, P5V, P3V3 and their EN signals when the 5V output (Buck output) in shutdown during the operation.

    Thanks!

    Phil

  • Hi Phil, 

    Thank you for the response. 

    Here is the waveform provided by customer:

    Ch1: The CLLC input power from car battery

    Ch2: The EN1 signal which is divided by P12V

    Ch3: P5V

    Ch4: P3V3

    Customer testing condition is to test the inverting function 350vdc/240vac at no load condition. The Buck output (P5V) is shutdown at the beginning. Since P5V is connected to EN2, so it will affect the LDO output (P3V3) .

    I have following question:

    1. Is there any protection mechanism other than OCP and thermal protection may cause the P5V shutdown?

    2. I found we have the D version of TPS65320-Q1. Could you help to provide me the change list of the IC? I'd like to know if the new version of TPS65320 can solve the problem. 

    Thank you!

    Pin Tsai

  • Hi Pin,

      From the waveform, there are lots of glitches; most of them are deep enough to cause under voltage protection. Please ask customer to make the input power source smooth. 

      The device has built-in protection features such as soft start, current limit, thermal sensing, and shutdown because of excessive power dissipation. Furthermore, the device has an internal under voltage lockout (UVLO) function that turns off the device at a too-low supply voltage.

      What do you mean "the D version of TPS65320-Q1"? The datasheet I download from TI website is a "Rev.F".

    Thanks!

    Phil

  • Hi Phil, 

    Thank you for the reply. Let's continue the discussion in the separate email. 

    Best, 

    Pin