FPGA Selection--

I've attempting to select an FPGA for a new design.

The design will have 9 of the following: 12 bit latches 12 bit down counter 1 bit output latch

So one measure of the size might be 25 registers * 9 = 225 registers.

The counting freq is 15 MHz.

The latches get loaded from an existing micro. So I need a 12 input pins for a data buss, 4 input pins for which register, a clock pin and let's say 4 pins for control lines. Along with the 9 output signals.

So another measure is 12+4+1+4+9 = 30 pins not counting power and ground.

It would also be desirable to be packaged in a PLCC but TQFP in ok.

And the device should be reprogrammable using JTAG (add 4 more pins).

Voltage is not much of an issue. However 5 V tolerant I/O would be nice.

I've looked at Lattice and Altera and haven't found the perfect solution. I can use larger than necessary Altera devices (ACEX1K) but that seems to be the wrong direction.

Any suggestions/recommendations.

Thanks George

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PLCC / 5V /15MHz / 225 registers is more trailing edge, so look at Atmel's AT40K FPGA family (meets all features), or possibly a CPLD - Lattices 4000 family have 5V tolerant I/O ?


Reply to
Jim Granville

There is the XCR3256XL

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This is a 256 macrocell part that operates at 3.3V. It has the required 225 flops (31 to spare), JTAG and is 5V tolerant on the I/Os. It is offered in both TQ and PLCC packages.

15 MHz would bea "piece of cake". It's overkill in the I/O , but more is better than less. Of course, there is a 1.8V version, but it does note tolerate 5V without extra circuitry on the outside.

Peter Alfke, Xilinx Applications ==================================

Reply to
Peter Alfke


Lattice's ispMACH4000 is a great family and available in different packages. However, George mentioned he want's to use a PQFP,and the ispMACH4000 is not available in PQFP. Ttherefore I would like to suggest a M4A3-256/128-10YC. This is the previous generation. If price matters, and George can live with TQPF (which is actual a smaller package) then he can chose the LC4256V-75T100C. This device has 64 IOs.



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"George" skrev i meddelandet news: snipped-for-privacy@posting.google.com...

Check out the AT94K10 or AT94K05. This gives you both the (AVR) micro and the FPGA.

Best Regards
Ulf at atmel dot com
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Reply to
Ulf Samuelsson

You don't need an FPGA for something that simple, look at CPLDs.

Reply to
General Schvantzkoph

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