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Original question:

TPS1663: eFuse starts up without microcontroller signal

TPS1663: TPS16630PWPR efuse circuit CHECK

MICHAEL MICHAEL
Prodigy 20 points
Part Number: TPS1663

Tool/software:

To Whom it may concern

My design have some issue.


Input 48V / 3A adapter

Total load around 1A


System can not boot seldom.



I would like to ask if there's any issue with the design of the efuse circuit.

Your prompt help will be highlt appriciated.

efuse circuit:

I ping voltage of D1 & D6 by OK time and failure time

OK TIME: 

01 meanwell 48V ACDC RS-150-48 on full turret (can power up)
01 meanwell 48V ACDC RS-150-48 on full turret (can power up)

02 meanwell 48V ACDC RS-150-48 on full turret (can power up) (zoomed in)
02 meanwell 48V ACDC RS-150-48 on full turret (can power up) (zoomed in)

Failure time:


03 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

03 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

04 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

04 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

05 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

05 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

06 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

06 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

07 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

07 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

08 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

08 meanwell 48V ACDC RS-150-48 on full turret (CANNOT power up)

  • 0
    TI__Mastermind 30681 points

    Hello Michael,

    Greetings.

    What's the start-up load current?

    What's the total output capacitance? 

    Are there more caps available after the circuit?

    Can you fill in the below calculator with your system value and send?

    https://dr-download.ti.com/design-tools-simulation/calculation-tool/MD-QV4CzjZsl1/01.00.00.0B/slvc765b.zip

    Thanks

    Amrit 

  • 0 in reply to Amrit Jit
    Prodigy 20 points

    Dear Amrit-JI

    Q:What's the start-up load current?

    A: Since this PCB is connected to the system’s PCB, and We don’t have other PCBs on hand to measure,
    I cannot determine the full loading. The system’s PCB is located in our Singapore office, and they informed me that there is a high inrush current during startup. This is because the 48V is converted into 12V, 5V, 3.3V, etc., including the motor startup. It is possible that the high current when the motor is powered on during startup is causing the issue, but we are still confirming this situalltion.

    Q:What's the total output capacitance? 

    A:Around 630uF 

    Q:Are there more caps available after the circuit?

    A:Around 630uF 

    Q:Can you fill in the below calculator with your system value and send?
    A: Pleas find attached file.

    03_48V_HD Lungteh Vin_20240301 (operating 41V~55V, lock 39V, 57V) applied.xlsx

    I have another issue that I’d like to consult.
    According to the IC's specifications, the SHDN pin maximum is 5V.
    However, the current circuit design exceeds 5V. Could this affect the IC?

    I have another model using the same IC TPS1663  and the same circuit, where the SHDN pin is pulled up to 36V, and so far, I haven't encountered any startup issues.

    I want to confirm whether the SHDN pin voltage is having a more significant impact or if the current limit is causing the startup problem.

    Thank you.

    REFERENCE:

  • +1 in reply to MICHAEL MICHAEL
    TI__Mastermind 30681 points

    Hi Michael,

    Thanks for giving detailed information.

    The eFuse failing to power issue is because of thermal shut-down which is causing the internal FET to shut down.

    Shut down is because of high power dissipation at start-up because of load current and inrush current.

    Please use higher dVdT cap. This will increase the start-up time of FET. Use around 0.12 uF dVdT cap. Increase the value little up if still failing.

    Use of SHDN pin looks to wrong in your schematic. It's used with microcontroller or optocoupler to shut down the efuse.

    If you don't wish to use it, just leave it floating or connect a resister divider to keep it below 5V.

    You can refer to 8.3.13 Low Current Shutdown Control (SHDN) section of datasheet for more info.

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Prodigy 20 points

    Thanks for your prompt help!!!