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Original question:

REF3333: Ref3333 chip damaged

LMR14030-Q1: Is it possible for LMR14030 to damage back-end chip when operating in sleep mode?

yong.fu
Prodigy 140 points
Part Number: LMR14030-Q1
Other Parts Discussed in Thread: LMR14030, REF3333

Tool/software:

Hello Experts,

I faced the issues about the LMR14030 and the Ref3333,

could you help to confirm the related link as below:REF3333: Ref3333 chip damaged - Power management forum - Power management - TI E2E support forums

LMR14030 operates in Sleep mode  not CCM or DCM mode due to the small load current, 

The ripple voltage of LMR14030 is 60mV,  its output not exceed the max rating.

Is it possible for the output of 5V to become a large voltage?  for example Over 10V.

Thank you.

BR Vincent

  • 0
    TI__Mastermind 26790 points

    Hi Vincent,

    Thank you for your question. When the LMR14030 is in sleep mode, it will operate as outlined in section 8.3.3 of the datasheet. There should be no risk for the LMR14030 to output 10 V when given that the device is being operated within its recommended voltage ratings and its components are not damaged.

    Additionally, there is overvoltage protection on the device that will prevent the output voltage from rising once the FB voltage reaches above 109% if the internal VREF. Please see section 8.3.10 in the datasheet for more details.

    Thank you,

    Joshua Austria

  • 0 in reply to Joshua Austria
    Prodigy 140 points

    Hello Joshua,

    Thank you for your reply,

    Is it possible that the LMR4030 output will become more than 10V? Because I tried to disconnect the output 5V of LMR14030 and the back-end chip in the circuit, and then used the DC power supply to supply power, when the voltage increased from 5Vuntil to 12V, the back-end REF3333 burned out, the phenomenon was consistent with the customer's site.
    ​

    Do you have any suggestions?  (Notes: the product LMR14030 is used for 12V system, the batt voltage is 9V-16V. there is a TVS before the LMR14030 input route. I also used another LMR14030, the same input is BATT, the output is 3.3V, to MCU and other power supply, working in CCM mode. There is no problem with this part of the circuit.)

    Thank you.

    BR Vincent

  • 0 in reply to yong.fu
    TI__Mastermind 26790 points

    Hi Vincent,

    Apologies, I am not understanding. Are you saying that you observed a output larger than 5 V at LMR14030 output after increasing the input voltage? What did you increase the input voltage to? Please take me through your tests and how you measured your voltages.

    The output of the LMR14030 should not rise above its regulation (I believe your circuit is set to 5 V) unless it is damaged or in an improper use-case. The output can rise to 10 V if the device is damaged.

    Thank you,

    Joshua Austria

  • 0 in reply to Joshua Austria
    Prodigy 140 points

    Hi Joshua

    I'm sorry to have confused you.

    When LMR14030 operated in sleep mode, I not tested the abnormal voltage.

    The test I conducted was to reproduce the phenomenon of burning REF3333 on customer site，I removed the inductance of the 5V block to make LMR14030 not work, and then applied a voltage at the 5V output, gradually increasing the voltage by 1V，When it reached 12V, it burned out the REF3333 at the back end.

    Thank you.

    BR Vincent

  • 0 in reply to yong.fu
    TI__Mastermind 26790 points

    Hi Vincent,

    Yes, as the REF3333 has an abs maximum input voltage of 7.5 V, the part will be damaged if its voltage is exceeded.

    In terms of the LMR14030, if the components of the circuit are not properly chosen, the device may behave erratically. While the overvoltage protection of the device should have not let the LMR14030 reach 7.5 V, it is still important to check the circuit to ensure that the proper datasheet parameters are being followed for expected behavior.

    Please check the following:

    • L905 should have a saturation current rating at least as high as the high side switch current limit (7.7 A) to avoid saturating.
    • The output capacitors must be specified such that the output voltage ripple is not too high. Section 8.2.2.4 of the datasheet outlines this procedure in detail.
    • The diode must meet the criteria outlined in section 8.2.2.5 of the datasheet
    • A feedforward capacitor is sometimes recommended for the device to operate in a stable range. Please see this app note for more details.
    • Please ensure that the proper snubber circuit is used. Please see this app note for more details.

    Thank you,

    Joshua Austria

  • 0 in reply to Joshua Austria
    Prodigy 140 points

    Hi Joshua,

    Thank you.

    I also checked the circuit, and the saturation current of L905  is 3.5A now, I tested  and confirmed the datasheet, the current is not exceed the 3A，and lower current in sleep mode. The output capacitor used is 47u+4.7u+0.1u, and there is no problem with the diode used.

    The Battery Electric Vehicle (BEV) produced from January to June was not damaged, and the Ranqe Extend Electric Vehicle (REV) model began mass production in May. I found that the recently problematic parts are all on this model. The difference between REV and BEV is that REV also has an additional engine system.

    Do you have any suggestions?

    Thank you.

    BR Vincent

  • 0 in reply to yong.fu
    TI__Mastermind 26790 points

    Hi Vincent,

    Other than the other suggestions above, I do not have much more advice to give about this without understanding if the LMR14030 is what caused the issue. 

    Have you been able to observe the output of the LMR14030 rising above 5 V to at least 7.5 V while in your use case? And if so, can you please provide screenshots for this?

    Thank you,

    Joshua Austria

  • 0 in reply to Joshua Austria
    Prodigy 140 points

    Hi Joshua,

    I did not find any issues on my bench, including power on/off, load transient, line transient, etc.  I inferred that there may be a high voltage output based on the phenomenon observed by the customer, so my previous question was about situations where there is a high voltage exceeding 10V, such as working in sleep mode

    Output is 5V, and Just the ripple is relatively large, 60mv, but this plus the ripple value also meets the backend power supply requirements（TCA1043A，REF3333,AD2428）.

    Thank you.

    BR Vincent

  • +1 in reply to yong.fu
    TI__Mastermind 26790 points

    Hi Vincent, 

    If this is the case, then I do not believe we can conclude that the issue is with the LMR14030 device. I will close this thread for now, but please feel free to reach out again should anything else arise.

    Thank you,

    Joshua Austria