what frequency to use?

Discussion in 'Embedded Systems and Microcontrollers' started by oookey, Jul 31, 2012.

  1. oookey

    Thread Starter Member

    May 24, 2010
    62
    0
    Hello, ;)

    I’m trying to use PIC16F628A to control 2 pcs of 74AHCT595 (Texas instrument) shift registers for matrix display.

    In the data sheets for both parts, max frequency for the MCU is 20Mhz, but the shift register min required 85Mhz! :eek:

    Would someone point me the right way of selecting the correct frequency? Thanks for your time.
     
  2. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    Hahaha. That's a funny idea they need at least 85 MHz.

    You can indeed apply pulses manually.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Not 85 MHz minimum... 85 MHz MAXIMUM.

    One pulse per day is acceptable.
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Page 7, fmax is at least 85MHz, this means it will work up to 85MHz or maybe higher, not that the minimum operating frequnecy is 85MHz.
     
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