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SN74HCS595: Feasibility for slow operating frequency

Part Number: SN74HCS595
Other Parts Discussed in Thread: SN74LV595A,

Hi team,

Could you give me comment on following customer question? SN74HCS595 and SN74LV595A are candidates for their use case. They consider if those device can be used from serial to parallel conversion with about 100kHz operation. Any serial interfaces are ok for UART, I2C, SCI, SPI. 

Q1. Can SN74HCS595 and SN74LV595A be used at about 100kHz slow operation frequency? LV595A has input transition requirement, but HCS595 is no requirement for input transition because it has Schmitt-trigger input. I assume SN74HCS595 looks better if they will use such slow 100kHz operation case. If you will come up with any other alternative proposal on 8-bit shift register, please let me know. 

Best regards,

Takeshi Sasaki

  • The clock frequency and the speed of the signal edges are two independent characteristics.

    There is no lower limit on the frequency.

    Schmitt-trigger inputs are necessary only if the edges are slower than the specified limit (e.g., 100 ns/V for LV at 3.3 V).