• State TI Thinks Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 19 subscribers
  • Views 2952 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TXS0108E logic level check and OE pin configuration

Anoop Abraham
Prodigy 110 points
Other Parts Discussed in Thread: TXS0108E, TXB0108

Hi,
I have to interface TDA8035 (Smart card interface IC with 3.3V supply) with PIC16LF877 (its supply voltage range is 2V to 5V, but due to some other interface coming to it, i need to use it with 5V supply).


For this requirement, i have selected TXS0108E. But it is having only 8-channels, my requirement is 12-channels. Therefore i am planning to use 8+4 arrangement. 

Maximum speed will be 8Mhz. And the signals can be from any directions at any time....

Please let me know if there is any problem in my selection also suggest a better one if any?

Thanks in advance,

Anoop

  • 0
    TI__Expert 6335 points
    Anoop,

    I'll get back to you later today. I am currently on travel. Thanks.

    Best Regards,
    Nirav
  • 0
    TI__Expert 6335 points
    Anoop,

    Please specify which pins you are planning to interface between the TDA8035 and PIC16LF877.

    Best Regards,
    Nirav
  • 0 in reply to Nirav Patel
    Prodigy 110 points

    Hi Nirav,

    Thanks for your prompt reply. Interface pin details are given in the below table.

    PIC16LF877 Pin Number

    PIC16LF877 Pin Name

    PIC16LF877 Buffer Type

    TDA8035 Pin Number

    TDA8035 Pin Name

    Signal Directions

    Through Level Shifter IC

    8

    RB0/INT

    ST

    1

    I/OUC

    Bi

    YES

    32

    RC0/T1OSO/T1CKI

    ST

    3

    _CMDVCCN

    Uni

    YES

    3

    RD5/PSP5

    ST/TTL

    6

    CLKDIV2

    Uni

    NO

    35

    RC1/T1OSI/CCP2

    ST

    7

    EN_5V/3VN

    Uni

    NO

    41

    RD3/PSP3

    ST/TTL

    9

    RSTIN

    Uni

    YES

    9

    RB1

    TTL

    10

    OFFN

    Bi

    YES

    10

    RB2

    TTL

    12

    XTAL1

    Uni

    YES

    1

    RC7/RX/DT

    ST

    29

    CS

    Uni

    YES

    24

    RA5/AN4/SS

    TTL

    30

    PRESN

    Uni

    NO

    44

    RC6/TX/CK

    ST

    31

    AUX1UC

    Bi

    YES

    43

    RC5/SDO

    ST

    32

    AUX2UC

    Bi

    YES

    Thanks,

    Anoop

  • 0 in reply to Anoop Abraham
    Prodigy 110 points

    Hi Nirav,

    Awaiting your reply.

    Please check and let me know your comments.

    Thanks,

    Anoop

    +91 9741377893

  • 0 in reply to Anoop Abraham
    TI__Expert 6335 points
    Anoop,

    So I've assumed that the connection path is shown below:

    TDA8035 (3.3V) <--> Port A (TXS0108E @ 3.3V) <--> Port B (TXS0108E @ 5.0V) <--> PIC16LF877 (5.0V)

    8 MHz operation is fine. When signal direction is from TDA8035 to PIC16LF877:

    TDA8035 VOH @ 3.3V must be > TXS0108E VIH @ VCCA = 3.3V
    TDA8025 VOL @ 3.3V must be < TXS0108E VIL @ VCCA = 3.3V

    TXS0108E VOH @ VCCB = 5.0V must be > PIC16LF877 VIH @ 5.0V
    TXS0108E VOL @ VCCB = 5.0V must be < PIC16LF877 VIL @ 5.0V

    When signal direction is from PIC16LF877 to TDA8035:

    PIC16LF877 VOH @ 5.0V must be > TXS0108E VIH @ VCCB = 5.0V
    PIC16LF877 VOL @ 5.0V must be < TXS0108E VIL @ VCCB = 5.0V

    TXS0108E VOH @ VCCA = 3.3V must be > TDA8035 VIH @ 3.3V
    TXS0108E VOL @ VCCA = 3.3V must be < TDA8025 VIL @ 3.3V

    You can use the procedure above to check the datasheets and verify that these conditions are met.

    Best Regards,
    Nirav
  • 0 in reply to Nirav Patel
    Prodigy 110 points

    Hi Nirav,

    It is connected as same as given below:

    TDA8035 (3.3V) <--> Port A (TXS0108E @ 3.3V) <--> Port B (TXS0108E @ 5.0V) <--> PIC16LF877 (5.0V).

    In the TXS0108 datasheet, it is recommended to connect a pull-down to OE pin and drive it from the controller pin. Since i do not have any pins left out in microcontroller, i am directly connecting OE pin to VCCA with a pull-up Res. and a Cap. from OE to GND (Cap is optional and it will be used incase if any delay is required for OE w.r.t VCCA). 

    Please let me know my approach on this (OE pin termination) will work or not.

    Thanks,

    Anoop



  • 0 in reply to Anoop Abraham
    TI__Expert 6335 points

    Anoop,

    Anoop Abraham said:

    In the TXS0108 datasheet, it is recommended to connect a pull-down to OE pin and drive it from the controller pin. Since i do not have any pins left out in microcontroller, i am directly connecting OE pin to VCCA with a pull-up Res. and a Cap. from OE to GND (Cap is optional and it will be used incase if any delay is required for OE w.r.t VCCA). 

    Please let me know my approach on this (OE pin termination) will work or not

    Yes that is an acceptable configuration. Also, you can short the OE pin directly to VCCA as well.
    Best Regards,
    Nirav
  • 0 in reply to Nirav Patel
    Prodigy 110 points

    Hi Nirav,

    I have taken all your recommendations into consideration and proceeding with PCB design.

    One more query: 

    What will be the product life of TXB0108/TXS0108?

    Thanks,

    Anoop

    9741377893