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TLV62065-Q1: When EN is connected with resistance, it worked abnormally

Amelie Zheng
Genius 10865 points
Part Number: TLV62065-Q1

Hi Team,

Customer met a very strange problem and now it could be solved. But we really want to figure out the reason.

Customer use TLV62065-Q1 to change 5V to 1.35V. 

As first they use resistance (100k and 10k) to divide the voltage from 3.3V as following:

The welding is ok, which customer has confirmed.

  • At the beginning, it could work normally but after a shoar time,the output voltage is 0V and en voltage is lower than 1V. When testing EN to GND impedance is lower than 15k and it is abnormal
  • When using Hot Air Gun to heat the TLV62065-Q1 about 100-200 ℃, it could work again.

And then they remove the resistance in EN pin, the system could work normally.

May I ask why when customer add resistance in EN pin, sometimes it could work but sometimes it couldn't? What is inside the EN pin?

  • 0
    TI__Genius 17341 points

    Hi Amelie,

     I am trying to understand the schematic. The application requires a higher UVLO by adjusting the input pin UVLO with two external resistors connecting to the enable pin. If they are planning to give external supply to enable then it doesn't require the resistor divider. is there any purpose to use it?

    Could you share more detail like waveforms and layout and operating conditions like load, temp? 

    Best regards,

    Tanvee

  • 0 in reply to Tanvee
    TI__Genius 10865 points

    Hi Tanvee,

    Thanks for your reply.

    They used resistor divider before, and are just curious why remove the divider resistor it could work normally, but when adding resistors, it just work normally sometimes...

    Is it because the internal resistor in EN PIN?

  • 0 in reply to Tanvee
    TI__Genius 10865 points

    Hi Tanvee,

    I just received a call from customer side.

    They used resistor divider before, and are just curious why remove the divider resistor it could work normally, but when adding resistors, it just work normally sometimes...

    Their concern are as following:

    • Is direct connection to 3.3V a foolproof connection, or are there other more recommended solutions for EN PIN?

    This is very important for customer because their project will be SOP soon, 

    • Why does the internal resistance of the EN pin change, and what effect does the voltage divider resistor have on the internal connection of ENABLE?

  • 0 in reply to Amelie Zheng
    TI__Genius 17341 points

    Hi Amelie,

    It doesn't look like a device problem. As I ask you before could you share more information about layout and waveforms of ENable pin in and out in their operation conditions?

    I am closing the thread as you can share data directly through the mail.

    Best regards,

    Tanvee