Hello,

I'm looking for a prescaler reference with a ratio of 64 and 128, able
to operate up to 3GHz.

I had in mind to use the Motorola MC12079 (64/128, 2.8GHz) but it's
discontinued. The fujitsu MB506 (64/128, 2.4GHz) is difficult to find.

Have you some other part numbers to suggest ?

Many thanks

Stephane, F1TJJ

You might consider one of the PLL chips, such as National's LMX2326,
especially if you already will have some digital control lines which
you can use to program it. That particular chip can do a 1/32
prescaling, followed by a divide-by-N, but for the LMX2326, N is 3
minimum, so it doesn't do quite what you want. Maybe another such chip
would. They are typically quite inexpensive.

Cheers,
Tom

Thanks for your answer Tom

I know this chip, but how do you do to output the pre-scaled signal ?
It would be suitable to use a PLL built-in prescaler if the output was
available on any pin but I don't think this is the case.
My appliaction is a frequency meter

Stephane



"K7ITM" a écrit dans le message de news:
...
You might consider one of the PLL chips, such as National's LMX2326,
especially if you already will have some digital control lines which
you can use to program it. That particular chip can do a 1/32
prescaling, followed by a divide-by-N, but for the LMX2326, N is 3
minimum, so it doesn't do quite what you want. Maybe another such chip
would. They are typically quite inexpensive.

Cheers,
Tom

Hi Stephane,

You should be able to program the Fo/LD output pin to echo the divider
output. See "Table 4" in the data sheet. If you are intent on getting
/32, you might check out the LMX2430 series. I think (from a very
quick look at the data sheet) that you'll be able to go to lower
division ratios with it. It also has a muxed output that can be
programmed to echo the divider chain output.

Maybe someone else knows a reason this won't work...I haven't actually
done it, but did look into it some time ago and didn't see anything in
the data sheet that would make me think it wouldn't work. Seems like
these chips are a lot easier to get than simple fast prescalers.
Programmable PLL chips from other manufacturers may work well too.
Cheers,
Tom

The following chip is not recommended for new designs but if its for a home
project it should be OK. See the following URL for the data sheet.

http://www.cel.com/pdf/datasheets/upb1506.pdf

There may also be newer versions available if you ask the manufacture.


--
Leland C. Scott
KC8LDO

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"Stephane" wrote in message
om...
Hello,

I'm looking for a prescaler reference with a ratio of 64 and 128, able
to operate up to 3GHz.

I had in mind to use the Motorola MC12079 (64/128, 2.8GHz) but it's
discontinued. The fujitsu MB506 (64/128, 2.4GHz) is difficult to find.

Have you some other part numbers to suggest ?

Many thanks

Stephane, F1TJJ