74HC165 vs 74HCT165 Shift registers and BCD Thumb-Wheel.
DavidM
Posts: 626
Hi,
Further to my success with the SHIFT REGISTERS I have another question
According to this article I found..
http://www.proteanlogic.com/applications/An043_old.pdf PAGE 4
There are two types of 74xx165 Shift Registers
the 74HC165 and the 74HCT165.
I believe the HCT version does not require pull-up resistors, so I could ( according to that PDF ) connect directly to the two BCD thumb-wheels without any resistors.
Is this the case?
regards
Dave M
Further to my success with the SHIFT REGISTERS I have another question
According to this article I found..
http://www.proteanlogic.com/applications/An043_old.pdf PAGE 4
There are two types of 74xx165 Shift Registers
the 74HC165 and the 74HCT165.
I believe the HCT version does not require pull-up resistors, so I could ( according to that PDF ) connect directly to the two BCD thumb-wheels without any resistors.
Is this the case?
regards
Dave M
Comments
The HCT series is useful when interfacing with +5V parts where the Propeller is driving the HCT device and the HC device runs at +5V. The HCT series is also useful when the HCT device is run off +3.3V and outputs directly to a Propeller input. None of this has anything to do with pull-ups on the inputs to the 74HCT165. You will need them. A useful value is somewhere between 4.7K and 10K.
I am still a little confused,
Why then does it mention in the PDF link a posted that resistors are not required? PAGE 4 ,
I am referring to the BCD device connecting to the SHIFT REGISTER.
regards
Dave M
Thanks for that. I will dispose of that document!
regards
Dave M