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Clock Divider by 256

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JamesIbox

Electrical
Jul 21, 2005
5
Hello,
I want to divide 8Mhz clock to 31.25Khz. So I guess I need a divider by 256 IC. I haven't worked with digital logic for so long now and I can't remember which IC does this. Would you please suggest which part I can use? Thanks!
Best regards,
 
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Eight flip/flops in series.
Use a counter on a micro.
 
There are, or at least were, also chips that did that. Prescalers, etc.

31.25 sounds vaguely like a video application, so there may already be video chips that do that

TTFN



 
The 74XXy93 and 74XXy90 circuits are counters that do that. The 74HCT393 from Philips is still being produced. Cost is about 30 cents in 100+ quantities. Another circuit would be the 74HC590 from Texas Instr. It is a lot more expensive, USD 1.30 in 100+ quantities.

Gunnar Englund
 
74VHC4040, a 12-stage counter chip with many intermediate divide values available. A single part would do the job. Packages from DIP to TSSOP. Price in the 50-cent range.


 
itsmoked, the CD series will not work with a clock source of more than 2MHz. The VHC can do in the hundreds of megs.


 
There are other versions of the 4040 and 4060 that will run fine at 25 MHz plus.
 
74HC4040:
minimum max operating frequency 24 MHz @ Vcc=4.5
minimum max operating frequency 28 MHz @ Vcc=6.0
both over Tamb -40 ~ +85 C.

Typical max operating frequencies @ 25C are 82 @Vcc=4.5
90 MHz Vcc=2, and 98 MHz @ Vcc=6.

Great 4xxx series functionality in the peppy 74HC family!


Jim
 
jimkirk; Thanks a lot! I use the HC series all the time. Easily my favorite. I just never stumbled across the 4040/60.
 
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