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TS5A23167: Antenna Switching

Sunil Kumar
Prodigy 20 points
Part Number: TS5A23167
Other Parts Discussed in Thread: SN74CBTLV3126, TMUX121

Hi,

I have connected 2 125KHz antennas to the switch TS5A23167 through which it is connected to the 125KHz reader, am using TS5A23167 to switch 125KHz antenna.

The Reader current is 45mA including antenna current. When the antenna is connected directly to the reader, the reading distance is good. 

But when i read it through the switch the distance is reduced more than 40%. The switch is offering .0.9 ohm resistance and 36 pf capacitance.

How can i adjust this 36pf or handle this scenario..?, 

or do you suggest any other switch for this application.

Many thanks.

  • 0
    TI__Mastermind 27758 points

    Hey Sunil,

    The 36pF isn't adjustable, It's a parasitic associated with the internal conductor within the device itself. So if you're wanting to reduce the overall capacitance of the trace, you'll want to pick a mux with less capacitance. The tricky part here is that the RON and CON are typically inversely correlated with each other, so lowering your capacitance will increase the resistance in most cases. 

    The SN74CBTLV3126 may provide the best combination of low RON and low CON while being able to support 45mA and keeping the same SPST configuration. Your RON will be a bit higher at 5ohms though. 

    I think in this case, I would go with the TMUX121 however. It is a SPDT but you can tie the SEL pin low and still just utilize the EN/ pin to give the same functionality as the SPST. 

    Let me know what you think

    Thanks,
    Rami