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CC2652P: Antenna Switch protection (TVS diode)

Tomas Varela
Intellectual 575 points
Part Number: CC2652P
Other Parts Discussed in Thread: CC1352P, TPD1E04U04

Hello,

We have our design with CC2652P based on the CC1352P LAUNCHPAD-2. In the antenna switch you have this TVS diode (swrc350a reference design): 

Unfortunately, this TPD1E0B04DPY is out of stock. We are thinking about using TPD1E1B04DPYT instead. The main differences are clamping voltage of 8.5V instead of 19V, and IO Capacitance of 1pF instead of 0.18pF. Do you think this will affect the performance of the antenna? In that case, do you have any other TVS diode to recommend to us, or it would just be better to not use it at all?

Thanks!

  • 0
    TI__Mastermind 20450 points

    Hi,

    You can select a diode with comparable capacitance.

    Regards

  • 0 in reply to FI
    Intellectual 575 points

    Hi,

    Thanks for your response. Consider the frequency of zigbee, can I consider 0.18pF comparable to 1pF?

    Best regards!

  • 0 in reply to Tomas Varela
    TI__Mastermind 20450 points

    Hi,

    0.18pF is not comparable to 1pF at 2.4GHz. The datasheet of the 2 devices suggests in the beginning the intended application use.

    0.18pF part is good for up to 20Gbps.

  • 0 in reply to FI
    Intellectual 575 points

    Hi,

    Unfortunately, I cannot change the footprint at the moment, so the closest alternative that I found is TPD1E04U04 which has 0.5pF capacitance. In the datasheet, it does not mention antenna applications but it states that is good up to 6Gbps, so for ZigBee 2.4GHz should be ok, right?

    However, this is a unidirectional TVS, and not bidirectional as the original. I don't fully understand why it has to be bidirectional. Can I use the unidirectional connected in such a way to protect the circuit from positive overvoltage? (anode to GND).

    Thanks!

  • 0 in reply to Tomas Varela
    TI__Mastermind 20450 points

    Hi,

    0.5pF value looks good but radio signal will have positive and negative swing and unidirectional diode may break down immediately in reverse bias and therefore clamping the signal voltage. You should use bidirectional ESD diode.

    regards

  • 0 in reply to FI
    Intellectual 575 points

    Hi,

    Thanks for your answer. I understand what you mean. We analyzed again our design and as our antenna is an integrated microstrip, we concluded that this protection might not be critical, especially for its cost. Moreover, our whole device is not especially ESD protected, therefore this single protection might not do a big difference in our case.

    Of course, let me know if you strongly disagree with any of these points. Thanks!

    Best regards,