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SN74CBT16232: MUX bi-directionality Issue

Onur YILDIZ
Prodigy 100 points
Part Number: SN74CBT16232

Hi,

I want to use SN74CBT16232DGGR MUX for selecting one of the two inputs to an output. As looking the datasheet, "A=B1" and "A=B2" operation is available.

  • Does it mean, "A will be the value of B1" and "A will be the value of B2"? As I understand from this logic operation, this MUX is not bi-directional (i.e. B1 cannot be the valu of A, etc.). Or "A=B1" means that "shorting the A and B1" (If you look thru the device schematic, you may see the MOSFETs, which means that I could use it as a "short-circuit", which makes this device as bi-directional I think.) ?

P.S: While I say "shorting", I do not mean an electrical short circuit, but I mean the bi-directional behavior between A and B pins, since MUX is a logical operation device.

Thanks.

Onur.

  • 0
    TI__Mastermind 45380 points

    Onur,

    All of the TI passive FET switches are bi-directional.  Passive FET switches create a low impedance path from the drain to source when the gate of the FET is biased to turn in on.  When gate is biased to turn the FET off it will create a Hi-Z path between the drain and the source of the FET.  For the SN74CBT16232 the drain of the FET is A and the source is B while the gate of the FET is not accessible directly by a pin and is internal to the IC. 

    Based on the truth table below you an see that there are 4 different combinations of turning on and off the internal FETs connecting A to B. 

    1) no low impedance path to from A to B1 or B2

    2) low impedance path from A to B1 and B2

    3) low impedance path from A to B1 and Hi-Z path from A to B2

    4) low impedance path from A to B2 and Hi-Z path from A to B1

    Thank you,

    Adam

    Either A can connect to B1, A can connect to B2,  A can connect to both B1 and B2, . 

  • 0 in reply to Adam Torma
    Prodigy 100 points

    Hi Adam,

    You explained and solved my problem exactly. Thank you in advance.

    Kind Regtards.

    Onur.