About ESD protection of ADV748x HDMI receiver

Hi,

There is no damping resistor in the HDMI input signal (RXA_0P, RXA_0N, etc.) line described in "adv748xebz-sch_b2.pdf".

Is there a possibility that the device will be damaged due to high voltage applied from the HDMI connector in ESD tests, etc.?

Is there ESD protection inside the device?

Best regards.

  • +1
    •  Analog Employees 
    on Oct 8, 2021 9:02 AM

    Hi Tatsuya-San,

    This RXA pin is 5V tolerant, ESD hits will be much greater than 5.5V and in some usage models the ESD hit will have more energy than the RXA_5V pin and its reliably handle.

    Since the device has internal ESD protection however when design boards designers always add extra external ESD protection just to enhance the protection.

    for example 100 Ohm resistor in series with the RXA_5V line right before the ADV7482.  The RXA_5V input is just a CMOS gate.  It doesn't power anything . A 100 Ohm series resistor in combination with internal ESD will protect the input against any ESD hits on the connector.  

    Note: ESD protection is limited.  If your environment exceeds this level on energy hits than there could be problems.  Normally we have not seen problems with just connecting this pin to the outside world.  Since the pin is an input only you can put a 100 Ohm resistor in series with it.  This way the ESD energy would get absorbed in the resistor instead of damaging the silicon.  Also an ESD protection circuit in front 100 Ohm resistor would help even more (digital inputs utilize a 100 Ohm series resistor for ESD protection).

    Thanks,

    Poornima