FPGA vs CPLD

Another point blurring the line between FPGA and CPLD is
pin-to-pin speed.  10 years ago an FPGA was clearly not
suited to fast asynchronous designs.  Modern FPGA's, while
not as fast as the fastest modern CPLD are often fast enough
for functions like address decoding and asynchronous memory
interface.

Also you will find both FPGA's and CPLD's with programmable
I/O standards (LVTTL, LVCMOS, SSTL, HSTL, LVDS...)

Price per gate is still less in FPGA, but the overall price
range now overlaps considerably.

Still:

if the design is static and fits in a CPLD, you're probably
going to get off cheaper with a CPLD.

if the design requires instant-on you're again probably better
off with a CPLD, although a few FPGA's have this feature.

if the design requires flexibility to download different
logic depending on the end use, you're generally better
off with FPGA due to both the SRAM-based infinite-reload
capability, and ease of fitting designs after the pinout
has been fixed.

Jim Granville <no.spam@designtools.co.nz> wrote in message news:<YfXNc.909$zS6.112816@news02.tsnz.net>...
> praveen wrote:
> > Hello,
> > What is the differences between FPGA and CPLD?
> > 
> > What basis on which i should select. whether to go for cpld or fpga?
> 
> 10 years ago, things were relatively simple :
>   FPGA's were pretty much all RAM/loader designs, with low power,
> and granular logic.
>   CPLDs were were higher power, fast with wide-logic terms, and
> limited in register count.
> 
>   These days, there is much more overlap and bluring of the lines.
> 
> # Some FPGAs are FLASH (Lattice, Actel)
> # Some CPLDs have granular logic ( MAX II )
> # Some CPLDs have RAM/Loader built in ( MAX II, Coolrunner... )
> # For lowest static power, modern CPLDs are << modern FPGA
> 
> The first point of selection would be the register count, then
> the logic/RAM/DSP considerations.
> 
> You could, in some cases, design with both ( or use uC + FPGA )
> to solve all the design problems.
> 
> -jg

Lets take an example and see what the concensus is:

Gate Count: 40K ASIC gates
Speed: 50 MHz
PinOut: 100 pins
Other: ???


One Configuration: Spartan-III would be a suitable fit with $20 
price tag (scaling to $10 with volume) + $3 prom.

Altenatives from Altera? Actel (may be anti fuse?)

Could some one fill in...

-Rajeev

Rajeev wrote:

> Lets take an example and see what the concensus is:
> 
> Gate Count: 40K ASIC gates
> Speed: 50 MHz
> PinOut: 100 pins
> Other: ???
> 
> 
> One Configuration: Spartan-III would be a suitable fit with $20
> price tag (scaling to $10 with volume) + $3 prom.
> 
> Altenatives from Altera? Actel (may be anti fuse?)
> 
> Could some one fill in...


Where is the relation with my posting?

Mario

Thomas Stanka wrote:

> Rene Tschaggelar <none@none.net> wrote:
> 
>>praveen wrote:
>>
>>>What is the differences between FPGA and CPLD?
>>
>>The common understanding is that CPLDs are EEPOM or Flash based
>>and have to be programmed once. They have up to say 512 Flipflops.
>>FPGAs on the other hand are RAM based, meaning they have to be 
>>programmed at every powerup. This usually happens with a small
>>external Flash, a CPU or whatever. The smallest FPFA is far bigger
>>than the biggest CPLD.
> 
> 
> That's pretty wrong. Actel has flashbased Fpgas (and antifuse based).
> 
> The main difference is that CPLDs are mainly focused on 
> Input->(fast)Logic->Register->Output
> while Fpgas are typically slower for CPLD tasks, but have more
> configuration possibillities and support more complex logic
> structures.
> A typical CPLD design would have fast but simple operations while a
> fpga has complex operations based on many internal registers.

True, Flash FPGAs blurr the line. However according to the data
I have available some of your statements are also not
correct. The fastest CPLD I came across does in the order of
220 MHz, and has no internal multiplier. Whereas the FPGAs,
at least the more modern ones tend to have clock multipliers
and 220 MHz is not considered fast at all.

Rene

Mario Trams <Mario.Trams@informatik.tu-chemnitz.de> wrote in message news:<cedcm7$nn7$1@anderson.hrz.tu-chemnitz.de>...
> Rajeev wrote:
> 
> > Lets take an example and see what the concensus is:
> > 
> > Gate Count: 40K ASIC gates
> > Speed: 50 MHz
> > PinOut: 100 pins
> > Other: ???
> > 
> > 
> > One Configuration: Spartan-III would be a suitable fit with $20
> > price tag (scaling to $10 with volume) + $3 prom.
> > 
> > Altenatives from Altera? Actel (may be anti fuse?)
> > 
> > Could some one fill in...
> 
> 
> Where is the relation with my posting?
> 
> Mario

Mario,

I was trying to being up an example so that we could see which techonlogy
from which vendor makes best sense. This happens to be a design I worked in
the past. 

-Rajeev