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TCA6416A Connecting Capacitor to Reset Pin

Sadanori Kato
Guru 36490 points
Other Parts Discussed in Thread: TCA6416A, TINA-TI

Hi,

Does TCA6416A work normally in the case of the power-on or the power-off if connecting the capacitor to the reset pin as below ?
Could you please give us your advice if you have any concerns ?

Best regards,
Kato

  • 0
    TI__Genius 16430 points
    Hello Kato,

    Do you happen to know the size of this proposed capacitor? If it is fairly small, I do not see any issues with a capacitor placed in that location, so long as you allow the RESET signal to be low for the minimum amount of time specified on page 8 of the data sheet in the Reset Timing Requirements. Keep in mind, that adding capacitance to the RESET pin will require that the minimum low pulse to get bigger since 4 ns of valid VIL must be seen to reset the device properly.
  • 0 in reply to Jonathan Valdez
    Guru 36490 points

    Hi Jonathan-san,

    Thank you for your quick response.
    Our customer is considering 1nF as the capacitor which is connected to the reset pin.
    Then, I have simulated the RC model by using the TINA-TI simulator as below.
    So, could you please give me your advice if you have any concerns with the power-off about /RESET2 which 33nF is connected although I believe that /RESET1 which 1nF is conneted is not any issues ?
    Moreover, does the internal POR(Power On Reset) work normally if TCA6146A is applied the power supply voltage after /RESET is applied 1.8V ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Genius 16430 points

    Kato-san,

    Good idea simulating the RC constant. We require that the RESET line be held low for a minimum of 4ns (at 0V) per the datasheet. RESET1 clearly satisfies this condition. RESET2 does not. You will likely have to hold the line low longer to allow for the capacitor to complete discharge before recharging it. With the waveform you are showing in RESET2, this could cause unexpected behavior on the device (it might reset, it might not).

    Regards,

    Jonathan

  • 0 in reply to Jonathan Valdez
    Guru 36490 points

    Hi Jonathan-san,

    Thank you for confirming.
    I understood and will inform our customer of your information.

    Best regards,
    Kato