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DIX4192: Using SRC4392 as an alternate to the DIX4192

Veselin Dimitrov
Prodigy 10 points

Part Number: DIX4192
Other Parts Discussed in Thread: SRC4392,

I am working on a new design and I would like to be able to use SRC4392 as a substitute for DIX4192 in case of supply chain issues in the future. Seems like hardware wise there are only pins 14 and 15 that are different. They are NC on DIX4192 and MUTE and RDY on the SRC4392. I was hoping not to have to add any extra components, so that it can be a straight swap in production and nothing else on the PCB would have to change. I would like to be able to just ground pin 14, but the DIX4192 datasheet says "No internal signal connection, internally bonded to ESD pad". And it says nothing else. 

So my questions are:

1. Is it OK if I straight ground pin14 on DIX4192, which would ground this ESD pad and are there any issues with that?

2. OR alternatively - on the SRC4392, what happens if the MUTE pin (14) is left floating (not tied low or high)?

Thanks

Veselin

  • 0
    TI__Mastermind 35921 points

    Hello Veselin,

    In general if there is circuity connected to a pin ( input pins in specific) it is always better to connect them to  L or H and not leave them floating as you don't want them to pick up some stray signals coupled to them. If it is a true NC, it can be left float. I don't foresee any issue grounding these  unused pins in your case.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 10 points

    Hi Arash, I fully agree that a true no connect pin would be OK to ground. However the pin that would end up being grounded (pin14 on DIX4192) is labeled in the datasheet as "ESD pad" and no further information is given as to what that means. Can you confirm if on DIX4192 it would be OK to ground the ESD pad?

    I would really also want to know if pin 14 on SRC4392 has any internal pull up or pull down resistors that would keep the pin form being accidentally set high or low by stray signals as you mentioned. 

    Thanks

    Veselin

  • 0 in reply to Veselin Dimitrov
    TI__Mastermind 35921 points

    Hello Veselin, these parts are very mature and thus there is not much documentation or internal schematic available to me to review it. However I would think an ESD pad connected to a NC pin should not create any problem if the NC pin  is grounded. I think of it as a regular input pin with ESD protection, now what happens if that pin is grounded? I think it is a similar scenario and should be ok.

    Mute pin, by its function should not be pulled high internally  as it makes the part mute by default  which is not what you want  (as Datasheet indicates The MUTE control bit in control register 0x2D is disabled by default). I am sure it doesn't have PU resistor to VDD, and DS doesn't explicitly say if pull down resistor is at this pin. So grounding it should be fine.

    Kind Regards,

    Arash