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CCS/SN74LV4052A: Multiplex MSP430 UART (TX & RX) with 3 external UART modules : BLE UART, 2G module UARTand GPS.

Haithem Rahmouni
Intellectual 605 points
Part Number: SN74LV4052A
Other Parts Discussed in Thread: SN74CB3Q3253, CD4052B

Tool/software: Code Composer Studio

Dear TI Support Team,

My design contains an MSP430 MCU with one UART, I would like to communicate with external modules(BLE, 2G, GPS) through this UART, I am looking to use the SN74LV4052A or SN74CB3Q3253 to multiplex the MSP430 UART (TX & RX) with BLE UART, 2G module UART and GPS module UART ( Baud rate may go up to 921600).

1) Could you please tell me what's the difference between the following technologies and what's the better for my application :

i -  SN74LV4052ARGYR: Dual 4-Channel Analog Multiplexer/Demultiplexer

and,

ii - SN74CB3Q3253RGYR : Multiplexer Switch ICs Dual 1-of-4 FET Mltplxr/Demltplxr.

and,

iii- CD4052B: CMOS Differential 4-Channel Analog Multiplexer/Demultiplexer with Logic-Level Conversion.

2) I request your advice about the reliability to use such a component in such case? 

3) Is there any precaution to consider in my design? ( schematic or PCB) , is there any similar schematic example accessible in TI website ?

Best Redgards,

Haithem.

  • 0
    TI__Expert 3180 points

    Hello Haithem,

    There are many things that differentiate the 3 switches that you mentioned (Bandwidth, Max VCC, propagation delay, etc.), these specs are weighed depending on you design. I have attached the table below:

    This table can be easily done by finding the parts you wish to compare in our portfolio of parts:

    and then:

    1) You select the parts you wish to compare

    2) You click them compare button

    As seen below:

    Now another thing you should understand about the switches is their slight difference in available functionality. 

    Both the CD4052B and the SN74LV4052A have the same functional capability as you can see in the block diagram, and the functions table provided in the datasheets, and seen below. These two switch have have two channels which you can switch between 4 different inputs, but it is of the differential output, which means you will allow a pair of signals to pass each time.

    CD4052B snippet (Page 17 and page 18):

    Functional Block Diagram:

    Function States (the part and the truth table are highlighted and circled):

    SN74LV4052A Datasheet snippet(Page 12):

    As for the SN74CB3Q3253, this switch also has two channel with a 4 to 1 switching configuration, however the difference comes from the fact that this switch has 2 output enable (1OE and 2OE) pins. This means that this part has the capability of releasing a pair of signals at the same time, or individual sets depending on whether one or both enables are set low. This is also shown in the data sheet of this part. I have attached the snippet of such below:

    SN74CB3Q3253 Datasheet snippet (Page 9):

    Please note that in the functions table, the OE and the A and Bx ports are labeled without a number in front (highlighted), different than that of the block diagram. That is to show that circled portion (decoder bits) apply to both channels. This means that although you can dictate which channel lets a signal pass or not with OE, you cannot mix different paths between the two channels. If you pass B1 for channel 1, you will pass B1 for channel 2, meaning 1B1 and 2B1 will be active, assuming both 1OE and 2OE are Low.

    As far as reliability for these devices in your use case, you can check the specs that are important to you in your design, and as long as they fall in the specs we mention in our datasheet, they will be fine. For reference, baud rate converts directly to Hz.

    Most of the datasheets we offer for these switches will have tips and layout examples to follow for placing this part in your design.

    Another thing you can do for looking for examples is looking at TI designs:

    Here we have a series of different systems created for other people to see.

    Thank you for your question, I hope this was helpful.

    Louie