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TPS28225: External resistor at PWM and GND

Part Number: TPS28225

Hello team,

On the datasheet 7.3.4.2 there is note about external resistor between PWM and GND.

What if I don't put any resistor between PWM and GND?
I believe it will disable 3-state mode, but will TPS28225 operate normally?

Also, is internal 27k resistor connected to VDD level?

Best Regards,
Kei Kuwahara

Best Regards,
Kei Kuwahara

  • Hi Kei,

    Thanks for reaching out.

    As mentioned in the section 7.3.4.2, the device operates in both regular PWM mode and tri-state mode. As long as the input signal to the PWM pin follows the regular PWM mode signature, the device will keep working in the PWM mode. If input at the PWM pin goes into the high impedance mode and if the voltage/timing threshold conditions are met as per the datasheet then the device will enter the tir-state mode.

    In short, yes, the device will work normally under PWM mode as long as the signal at the PWM pin meets the requirement.

    Please let us know if you have any other question. 

    Regards,

    Ritesh

  • Hi Ritesh-san,

    Thank you for a quick answer!
    Understood about the PWM input.

    I have one more question.
    Is internal 27k resistor connected to VDD level?

    Best Regards,
    Kei Kuwahara

  • Hi Kei,

    I believe so but let me double check with my design team.

    Thanks and regards,

    Ritesh

  • Hi Kei,

    I have confirmed with my team that the 27k internal reistor is indeed tied to VDD through a series NMOS. Similarly, the internal 13k pull down is through series PMOS.

    Please let us know if you have any other question.

    Thanks.

    Ritesh