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SN74LV4052A: UART Signal

na na78
Guru 16770 points
Part Number: SN74LV4052A
Other Parts Discussed in Thread: TS5A23159

Hi

We are considering use of SN74LV4052A for multiplexing 5V UART signal (TX/RX).

Do you think it can be used without any issues?

TS5A23159 is also considered as analog switch that offers same function, but SN74LV4052A is lower cost.

If TS5A23159 is more reasonable, we should consider it.

Could you please tell me your view?

BestRegards

  • 0
    TI__Mastermind 45350 points

    Na Na,

    When considering if a switch can be used for an application you need to look at voltage and bandwidth requirements of your signal and the number of inputs and outputs of the switch you need in your system.

    You say you are tying to multiplex 5V signals but what is the bandwidth?  The TS5A23159 and SN74LV4052A both support 5V signals and have similar ~10s of MHz bandwidth so there isn't much difference in selecting between the two based on these parameters.  

    How many signals are you trying to switch to how many different places?  The TS5A23159 is a 2-channel 1:2 switch and the SN74LV4052A is a 2-channel 1:4 switch.  One device is taking one TX RX pair to 2 different locations and the other is taking one TX RX pair to 4 different locations.  

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Guru 16770 points
    Hi Adam

    Thank you for your reply.

    Regarding to the usecase this time, TS5A23159 seems to match.
    But SN74LV4052A would be considered in the future.

    I'm just wondering if analog switch like SN74LV4052A can be used for digital signal like UART.
    And I would like to know if there is any concern for such usecase.

    BestRegards
  • 0 in reply to na na78
    TI__Mastermind 45350 points

    Na Na,

    All of these devices are passive FET switches and will pass what ever signal comes on one side of the signal path to the other with little distortion.  As long as the voltages and bandwidth are supported by the switch you may pass what ever signal you would like UART, SPI, I2C, Audio, Video etc.

    Here is a good post explaining what is going on inside TI signal switches.  

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Guru 16770 points

    Hi Adam

    Thank you for your reply.

    Is it appropriate to suppose the following image If we would refer the internal circuit at IO port of the SN74LV4052A?

    (I think it should be considered clamp diode is present to VCC and GND)

    BestRegards

  • 0 in reply to na na78
    TI__Mastermind 45350 points

    The above internal circuit gives a general idea of the paracitics inside a signal switch.  This not a complete model as you mentioned that there could be an existence of clamp diodes on the I/O path for some signal switches but not all.

    In most datasheets you can check to see if there is a clamp diode on the I/O path to Vcc and ground in the abs max table.  If there is a clamp diode present you will see that the maximum voltage on the I/O will be with respect to Vcc.

    For example the SN74LV4052A has these clamp diodes on the I/O path