What's the main difference between FPGA &CPLD ???

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Gregcooler

Joined: 27 Jun 2002
Posts: 14

29 Jul 2002 16:57 What's the main difference between FPGA &CPLD ???

What's the main difference between FPGA & CPLD ???

gabby

Joined: 18 Mar 2002
Posts: 97
Location: Israel

29 Jul 2002 17:56

Hi

There are three big difference:

1. the internal archi.. the fpga use lookuptables that are 4x1 mem cells,
and the most new cpld cells have one ff+aditional logic array of and+or gates.
Some kind of special fpga have also some special blocks for implement
of system on chip(soc) that usefull for build uc/up/dsp inside.

2. Most fpga based on ram cells so evry time you power up you need
boot them from mem or aditional uc/uc/dsp, also you can cange it desing
in system work(careful).
the cpld based in otp fuse or flash fuse so you don't need boot them.

3. the most of the cpld are not big like the fgpa
most cpld are in range of 1k-50k(~100k) gates equvalent
fpga today you can find in range over some milion gates equvalent

cpld are more popular is small design for glue logic some state mechine
and some fast app, etc..

fpga are more popular in big design when is need of mem and machine
that need a lot of ff,also in system on chips(for reduce space or
for develop design before asic productions).

Best regards. Cool

kot_b

Joined: 28 Dec 2001
Posts: 115
Helped: 3
Location: Latvia

31 Jul 2002 11:23

Hi, but what is this "ff"? Question

GuruJosh

Joined: 26 Apr 2001
Posts: 11

31 Jul 2002 11:35

kot_b wrote:

Hi, but what is this "ff"? Question

ff = Flip-Flop

kot_b

Joined: 28 Dec 2001
Posts: 115
Helped: 3
Location: Latvia

31 Jul 2002 11:41

GuruJosh
Thanks...
Have you been using FPGA or CPLD?

ME

Joined: 14 Mar 2002
Posts: 1523
Helped: 13

11 May 2003 18:53

CPLDs contains many logic units (gates) and few flip-flops.
FPGAs contains many flip-flops and few logic units (gates).

CPLDs only have to programmed once (nonvolatile).

FPGAs need an external memory with program since it have to be programmed at every power-up (volatile).

satya

Joined: 14 Jun 2001
Posts: 85
Helped: 2
Location: bangalore

12 May 2003 4:38

hi,
check out Dr.Jonathan Rose Publications on Fpga. There is an article the gives the architectural differences b/w CPLDs and FPGAs.
The link:
http://www.eecg.toronto.edu/~jayar/pubs/pubs.html
Njoy...

Regards,
- satya

jodokus

Joined: 12 Feb 2002
Posts: 102

12 May 2003 8:59

cpld's are generally faster
cpld's are good for simple algorithms such as gleu logic.
FPGA's are better for complex algorithms.
small FPGA's are generally cheaper than complex cpld's.

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gauiver

Joined: 10 May 2003
Posts: 102

12 May 2003 10:38

CPLD's are implmented in the way like PAL's but FPGA's are implemented in a gate array approach. u need PALSM and environments like taht to program CPLD's and u use max+2 environment and VHDL and Verilog HDL to program FPGA's. also about the internal structure u can get more on this pdf.

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satya

Joined: 14 Jun 2001
Posts: 85
Helped: 2
Location: bangalore

12 May 2003 11:48

I have some points regarding the differences:
1.CPLDs as such have no specific architecture. They are just an array of PLDs in order increase the gate complexity resources. Even complex designs cannot be run on CPLDs as the number of cells provided is very less.
2. In contrast, FPGAs have the 2-dimenstional architecture in which each CLB will have 2-SLICEs. Main features are :
1. HIgher frequency of operation
2. Very Huge available memory blocks
3. In Built Multipliers for floating point arithmetic
4. DLLs for clock multiplication and division
HOpe this helps.
Regards,
- satya

satya

Joined: 14 Jun 2001
Posts: 85
Helped: 2
Location: bangalore

12 May 2003 11:56

Hi,
check this link. U will get some more information on CPLDs and FPGAs.
www.optimagic.com/faq.html

Regards,
- satya

ME

Joined: 14 Mar 2002
Posts: 1523
Helped: 13

15 Jun 2003 14:34

Check the last section in this link too:
FPGAs vs. CPLDs: www.fpga4fun.com/whatarethey.html

jacneo

Joined: 24 Jul 2002
Posts: 60

16 Jun 2003 15:59

I think the gate counters are the most different point.

gck

Joined: 17 Oct 2006
Posts: 149
Helped: 5

28 May 2007 8:04 Re: What's the main difference between FPGA &CPLD ???

I heard that, now days there are ROM based FPGA. Pls anybody can put light on that.

sp_harikrish

Joined: 29 Mar 2006
Posts: 23

31 May 2007 13:51 Re: What's the main difference between FPGA &CPLD ???

They are basically differs in architecture. Logic cells and their size are vary.
CPLD has very low speed where as the FPGA has MUX and high speed design.

CPLD has ROM based and FPGA has RAM based.

FPGA has more logic cells