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TPS2660: About reverse polarity protection on UVLO pin

Tao_2199
Genius 5770 points
Part Number: TPS2660

Hello,

 

Regarding to reverse polarity protection on TPS2660, my customer is asking a question.

According to datasheet page 21, reverse polarity protection is described as following.

“In the applications where reverse polarity protection is required connect a minimum of 300-kΩ resistor between UVLO and IN_SYS.”

 

(Question)

Could you please tell me why 300-kΩ resistor can protect to reverse polarity( min -60V)?

(The reason of why the resistor is 300kΩ minimum.)

 

Regards,

Tao_2199

  • 0
    TI__Guru** 105361 points

    Hi Tao,

    UVLO is rated to -0.3V on the negative side. So, min 300kOhm is recommended to protect UVLO pin under reverse polarity condition.

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Genius 5770 points

    Hello Rakesh.

     

    Thank you for reply.

    I have additional question.

     

    ･Why 300-kΩ resistor can protect from -0.3V(UVLO minimum rate)?

    Does this device protect UVLO pin by internal protect diode?

    Or is it related with UVLO Input leakage current?

    Could you please tell us theoretical explanation more detail?

     

    Regards,

    Tao_2199

  • 0 in reply to Tao_2199
    TI__Guru** 105361 points

    Hi Tao,

    As you know, each pin has ESD diodes. These diodes get forward biased under reverse polarity condition and excessive currents could flow leading to the damage. To avoid that, -0.3V limit is imposed in the spec. The other way is to use a resistor in the path to limit the currents (under few mA) through the ESD diode under reverse polarity condition. This is what the 300-kΩ resistor does here.

    Best Regards, Rakesh