CD74HC4024: Clock Division

JAMIE BROCK

Prodigy 150 points

Part Number: CD74HC4024

Hello

I need to divide a 97KHz clock by either 96,64 or 128.

Ive been advised to use a CD74HC4024.

Looking at the datasheet

1. I cant see how it works as unsure what type of flip flop is being used so cant work out the operation.

2. It doesnt dsay which would end up being the lsb and msb of the counter.

Logic diagram is below.

Can anyone please explain how you could use this as a clock divider, or if there is a better component to use a s a clock diver?

Thanks for your help

Jamie

over 5 years ago

0 Dylan Hubbard over 5 years ago

TI__Mastermind 43480 points

Hi Jamie,

This device should work for you. Each stage contains a master-slave flip flop that toggles on the falling edge of the clock pin. Since stage 1 has the external clock fed into it, it is the LSB since it divides that clock by two. Each of the consecutive stages has the output of the previous stage connected to their clock pin which will then divide that respective output by two. So Q7 (MSB) will be 1/128th of the input clock.

Let me know if that makes sense.

0 JAMIE BROCK over 5 years ago in reply to Dylan Hubbard

Prodigy 150 points

Hi Dylan

Thanks for the advice, thats all clear now.

One last thing is, can the MR pin be tied directly to ground or does the IC have to go thru a reset eg with an RC on reset pin at power up?

Thanks
Jamie

0 Dylan Hubbard over 5 years ago in reply to JAMIE BROCK

TI__Mastermind 43480 points

Hi Jamie,

As each stage contains a latched device, I'd advise a power on reset since the output state will be unknown otherwise. Take a look at the FAQ below to get more details on what i'm talking about.

0 JAMIE BROCK over 5 years ago in reply to Dylan Hubbard

Prodigy 150 points

Thats great, thanks for your help :)

Jamie

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CD74HC4024: Clock Division