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TPS548A20: What is TPS548A20 behavior when TRIP terminal is shorted to GND?

Part Number: TPS548A20

 Hello guys,

 One of our customers is considering using TPS548A20. They have several questions as the follows. Could you please give me your answer or comment?

Q1. What is TPS548A20 behavior when the resistor value between TRIP terminal (No.25) and GND (RTRIP) is less than 20kohm(Minimum value of recommendation)?

Q2. What is the device behavior when TRIP terminal is shorted to GND?

Q3. What is the device behavior when RTRIP is more than 65kohm(Maximum value of recommendation)?

Q4. What is the behavier when TRIP terminal is left open?

Q5. What is the behavior when TRIP termimnal is shorted to VO terminal (No.24)?

Q6. What is the behavior when TRIP termimnal is shorted to NC terminal (No.26)?

 Your answers would be much appreciated.

 Best regards,

 Kazuya Nakai.

  • TPS548A20 is not designed to work under those conditions.  Let me see if we have any specific information.

  • Hi John,
    Thank you very much for your reply.
    The customer know that these are irregular conditions. But they are cautious about such irregular conditions to design a high reliable product. Just your expectation is no problem. Could you give me it for them?

    Thank you very much again and best regards,
    Kazuya Nakai.
  • I have some limited information. Obviously, ITRIP shorted to NC is no issue. The others either may take some time or may be unavailable.
  • Hi John,

    I understood that ITRIP shorted to NC is no issue. I hope you have any information for other conditions.

    Thank you very much and best regards,
    Kazuya Nakai.
  • Hi Kazuya,

    Q1, Q2, Q3, Q4 We did not evaluate the device with these conditions.
    Q5. This test was perform before the part was released. The part operated "ok" but there is a possibility to be broken. The TRIP voltage determines the OCP level which now depends on the VO pin voltage level. The OCP will NOT be as intended.
    Q6. This test was perform before the part was released. The part operated fine.

    Amnat
  • Hi Newey,

    Thank you very much for the information.
    Your reply is very helpful for the customer and me.

    Best regards,
    Kazuya Nakai.
  • Hello Newey,

    Could I ask you a few same or similar questions again because the customer will use a competitor device if they can not get any answer to the following questions? They is evaluation the device on their own PCB board and there is no big issue so far. But they are worry about the device behaivior with the RTRIP irregular conditions.

    Q1. When RTRIP(the resistor value between TRIP-GND) becomes larger, is OCP current value increased?

    Q2. In the Q1 case, is there any higher limit of OCP? When RTRIP is much large, does OCP not work (no limit current value)?

    Q3. When RTRIP(the resistor value between TRIP-GND) becomes smaller, is OCP current value decreased?

    Q4. In the Q3 case, is there any lower limit of OCP? When RTRIP is much small, does OCP always work regardless the output current?

    Q5. Does your answer for Q5 mean that OCP doesn't work at all output current conditions.

    Q6. When TRIP terminal is shorted to VO terminal, is TPS548A20 broken with Vout shorting to GND?

    The customer needs your answers to proceed to their mass production.

    Thank you and best regards,
    Kazuya Nakai.
  • Hello Kazuya,

    Q1. Yes.
    Q2. Yes, there is higher limit. The higher limit of OCP needs to have RTRIP lower than 65K. We do not guarantee the OC accuracy for RTRIP higher than 65K. Please see section 7.3.7 in the datasheet.
    Q3. Yes.
    Q4. Yes, there is lower limit. The lower limit of OCP needs to have RTRIP higher than 20K. We do not guarantee the OC accuracy for RTRIP lower than 20K. Please see section 7.3.7 in the datasheet.
    Q5. It means that the part was working fine; however, the OCP may not be working at all output current condition.
    Q6. Yes, this can break the device since the OC protection is not working as intended.