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Cannot find a 1.8V devcie which are parallel in and serial out like SN74165

Martin Wen
Prodigy 615 points
Other Parts Discussed in Thread: CD74AC299, CD74AC323

Hi Bro,

Do we have any 1.8V device which are parallel in and serial out like SN74165. 

In our application, we have 100 1.8V I/O which need to transfer to 3.3V serial input to controller. If we use level shift first, the cost is too high and the application is too complicated. 

Thanks. 

  • 0
    TI__Guru* 97046 points
    Hello,
    Our response will be delayed due to the holidays.
  • 0
    TI__Guru* 97046 points
    Hi Martin,
    CD74AC299 or CD74AC323 could be used in this application - they support multiple modes of operation (serial in, parallel in, shift left, shift right) and support 1.5V to 5.5V operation. They aren't as simple as the '165, but will do the job.
  • 0 in reply to Emrys Maier
    TI__Prodigy 615 points

    Hi Maier,

    Thanks for your reply and Merry Christmas.

    Could you please help describing more detail? I cannot under how to use it. Thanks.

  • 0 in reply to Martin Wen
    TI__Guru* 97046 points
    Hi Martin,
    I understand - that datasheet is a bit confusing! Unfortunately, this is a part made by a different manufacturer and acquired by TI, so this is basically all the information we have on it. I will try to help make it clearer.

    First, the device has 8 I/O pins, labelled as I/O0 through I/O7. These are what you will use as parallel inputs.

    OE1\ and OE2\ control all of the outputs should be held LOW for normal operation. If either is set to HIGH, then the outputs are put into High Impedance mode.

    MR\ will clear all registers (set to LOW) and is probably not required for a parallel-input application (just short to Vcc)

    I would recommend operating the device in the "Shift Right" function since that makes the most logical sense to me. This means that S0 is held HIGH and S1 is held LOW. Data is input on DS0 and will shift through the register with each clock rising edge in the order of DS0 -> Q0 -> Q1 -> Q2 -> ... -> Q7. Note that the register names Q0 through Q7 correspond with the 3-state I/O pins I/O0 to I/O7. These are not exactly the same -- for example, Q7 is a direct connection to the register value, while I/O7 is configured as the register input for this design.

    Q7 (pin 17) is the output of the device for serial reading at the controller.

    Any unused inputs should be terminated appropriately (ie connected to Vcc or Gnd).