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LM36274 no output

JeffYC Yang
Expert 1290 points
Other Parts Discussed in Thread: LM36274

Hi Sir,

My customer meet LM36274 no output issue, we cannot set 0x08 bit 4, BL_EN to 1, seems caused by TSD(Thermal Shutdown), we read 0x0F bit 6(TSD) always 1,  but IC have no high temperature symptom, do you have any idea about this issue? I also attach LM36274 schematic FYR.

Thanks!

Jeff

  • 0
    TI__Intellectual 2140 points

    Hi,

    We have never encountered this type of issue with the LM36274. Please try the following enable sequence:

    - Set the backlight brightness level very low (register 0x04)

    - Set the OVP level (register 0x02) to 29V

    - Enable only one LED string (register 0x08)

    - Enable the backlight (register 0x08). You can combine this with the previous step.

    Under these conditions the power dissipated on the LM36274 will be very low. Even at max LED current and max ambient temperature the LM36274 should not enter thermal shutdown but if you still experience the problem something may be wrong with the board or the LM36274 has been damaged.

    Can you observe the input (supply) current when the part is disabled? A high input current would indicate damage on the device.

    I hope this helps, please let me know if I can be of further assistance.

    Regards,

    Angelos Tsiros

  • 0 in reply to Angelos Tsiros
    Expert 1290 points
    Hi Angelos,

    Thanks for your reply firstly!
    We will Try these item and check TSD status.