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Original question:

TPS92692: TPS92692 reference circuit

TPS92692: TPS92692 Burn

Kami Huang60
Genius 3830 points
Part Number: TPS92692

Dear Sri/Ms.

1. When the action is normal operation, the 19pin Duty will be big and small. As shown in the attached picture.


2.Protection testing.  Remove the LED string and test if there is any action, but found that TPS92692 burned out. Test resistance grouping,
It was found that the CSP exhibited a low impedance state. The hook FLT Pin3 has a pull LOW, and the measured CSP (R37) voltage is only 40V. Customer try to change the switching frequency 200Khz, and adjust the switching frequency up to 400Khz. TPS92692 still burned.
Excuse me, would you please guide us? How to solve this bug?

Best Regards,

Kami Huang

  • 0
    TI__Mastermind 18890 points
    Hi Kami,

    1. The gate drive voltage (pin 19) shows instability and it might be due to not having any filter feeding back to pin IS (pin 18). We usually recommend a filter of 100 Ohm and 1000pF from Ris (R30) back to IS (pin 18). Please see our data sheet page 41 figure 54 for this. The other reason for this instability can be due to compensation or layout. Did you follow the calculations for the compensation Cap (C14) or power stage design? The output capacitance (C8-C10) from Vout to Vin is only 3uF...This seems low.

    2. The values of R33 and R34 set the over-voltage protection on the LED voltage is 36V. What is the input voltage on? The max voltage feeding back to the TPS92692 is 65V relative to ground and if you exceed this the part will be damaged.

    We do have an evaluation board for the TPS92692 and you should get the board to test and change values ect. for your design as a starting point.

    www.ti.com/.../slvub29.pdf

    Thanks Tuan
  • 0 in reply to Tuan Tran74
    TI__Mastermind 18890 points
    Hi Kami,
    We have not heard back from you so we believe you may have solved the issue.
    The thread will close now but will reopen if you reply.

    Thanks Tuan
  • 0 in reply to Tuan Tran74
    Genius 3830 points
    Hello Tuan,
    Thanks for you kindly help.
    Customer solve their problem.
    Best Regards,
    Kami Huang