Hi,
I'm looking for an analog mux switch that can pass through bidirectional 3.3V logic signals while also passing through 4-5V switch signals. Current preference was towards using the SN74CBT3257. Is this a good choice? Or can you recommend a bi-directional analog switch with 3 signal paths with the following specs :
1) Supply Voltage (VCC) : 3.6V - 5V (single supply)
2) SPDT 2:1
3) 3.3V and 4-5V signals
4) Speed 3MHz max
Regards,
Leo
Leo,
The SN74CBT3257 meets most of your requirements below but the SN74CBTXXXX family of switches are single N-channel FET switches. This means it will not support voltages up to Vcc on the signal path. As you can see below the transfer function of the input to the output is very linear until the input voltage reaches Vcc - ~1V. At this point the FET is beginning to turn off and will clip voltages above Vcc - ~1V.
If you bias the switch Vcc = 5V you will be able to support 3.3 V signals without issue but 5V signals will be clipped to about 4V.
If you would like a similar switch that can support rail to rail signals you can look at the CD4053B.
Thank you,
Adam
