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TS3A44159: How to define the max input frequency of TS3A44159

Part Number: TS3A44159
Other Parts Discussed in Thread: SN74CB3Q3257, TS3A27518E

Hi all. It is so nice to find you all here. I used this device to control the SIM_CLK signal (rise time is 10 ns,f=4.9MHz). When the signal pass the TS3A44159, the waveform will change from square to triangular wave. So I use an 0 R resistor to connect the input and output of MUX together, the signal will be normal. The on capacitance may be the reason. What other reason may cause this problem?  I have another question is that how to calculate the max frequency of this device that can normally operate? Thank you!

  • Charles,

    The TS3A44159 does have large parasitic input capacitance >150pF.  If you do not have a strong enough driver this can load down your bus and slow down the edges of your signal.  

    The switches and multiplexers FAQ page has a recommendation for what datarate a switch will support.

    There are other 4-channel 2:1 switches will lower input capacitance I found on the TI.com switch search tool filters like the SN74CB3Q3257.  I have also seen customers request TS3A27518E for SIM card applications.