FIFO as a Logic Analyzer; Clock synthesizer

Apr 21, 2005 1 Replies

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nospam 21 years ago

Hi! I have a big FIFO chip covered by dust, that I'd like to finally use. The most useful application I'm imagining for it is to finally make myself a logic analyzer. This FIFO (Texas Instruments SN74V3690-6PEU) is a 3.3V device, but has 5V tolerant inputs. "Great!" I thought.

What I'm asking you is: should I connect the probes (just a header cable) directly to the FIFO, or should I use an high speed buffer inbetween? Consider that the chip is specced at 166MHz.

Moreover, what is the cheapest way to produce a variable clock speed up to 166MHz (and possibly beyond, for other applications)? A PLL? Any chip you may suggest me?

Thanks! TPM

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Paul Carpenter 21 years ago

I personally would buffer as a mistake on the inputs could blow the inexpensive buffer, and depends on how easy it is to get those FIFO chips in 6 months time.

For quite a lot of PLLs I use ICS whole range of fixed and programmeable PLL and clock drivers. Simple chip and an oscillator/crystal can get very cheap multiples, I find cheap and easy for video and LCD driving (lots of different clock rates).

To achieve 166MHz will be something in their standard parts as quite a few parts have used that type of clock multiplied up from a much lowere clock.

Paul Carpenter | paul@pcserviceselectronics.co.uk PC Services GNU H8 & mailing list info For those web sites you hate

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