Pull up or down for 74HC237

[Murugesh_89]

Hi,

I am interfacing the port D pins of PIC microcontroller to the A,B,C, E2 pins of the decoder IC 74HC237.

D0 - A,
D1 - B,
D2 - C,
D3 - E2

I am little confused with the selection of pull up or pull down resistors at the input of 74HC237.

Can anybody pls tell whether i need to put either pull up or pull down resistors?

Thanks,
Murugesh

 

[pic.programmer]

Use 10k resistors as pullups.

 

[KlausST]

Hi,

why do you need pullup/pulldown?

Use pullup/pulldown:
* on unused input pins: Then use a pulldown if you want the input to be LOW, or a pullup when you want the input to be high
* use pullup on open collector /open drain outputs
* or to give the 237 inputs a defined logic level as long as the PIC port is not initialized. If there is a need for it. Then use a pulldown if you want the input to be LOW, or a pullup when you want the input to be high

Klaus