Lpc2000

Frank
 
I work for a scientific research organization that places instruments on the ocean floor for long periods.  Our instruments live and die by power consumption.
 
Most of the SRAM based FPGAs have quiescent current consumption(i.e. no clocks) that will dwarf the current required by the LPC2106.   In order to achieve the density and speed required for the telecommunications market the MOSFETs used in these FPGAs are typically very leaky.  
 
Their gate threshold and bias voltages are very close resulting in a MOSFET that doesn't really turn fully on or off.  The quiescent current required by many devices can be on the order of 20 to 100 milliamps doing absolutely nothing.  Also, this quiescent current is exponentially dependent on temperature. 
 
Another thing to watch out for in the inrush/initialization current required by most of the
SRAM based FPGAs which can be on the order of amps.  Things change everyday in the
FPGA business so these comments may not apply directly to your specific part.  In other words, read that darn data sheet (carefully)!
 
For example, the Xilinx XC3S1000 typically requires 65 milliamps of quiescent current for the internal supply, VCCINT.  Another 25 milliamps is required for the VCCAUX supply. 
 
All is not lost, there are a few CPLD and FPGA like devices that feature low static power dissipation, here are a few recommendations:
 
1.  The Xilinx Cool Runner and Cool Runner II CPLDs (up to 512 macrocells)
2.  The Actel ProASIC and ProASIC+ FPGAs
3.  The Cypress Delta 39K family of CPLDs (up to 3072 macrocells)
4.  QuickLogic Eclipse II FPGAs
5.  Xilinx Spartan-XL (not Spartan 2, 3 or E) FPGAs
 
I have direct design experience with #1, 2 and 3 above but 4 and 5 may work for 
you as well.  I don't think the Quicklogic parts are re-programmable and cheap
HDL synthesis support for #5 is lacking.
 
I hope this helps...
Wayne

Frank Sergeant <frank@...> wrote:
"leon_heller" <leon_heller@...> writes:

> Some time ago I mentioned that I was thinking of producing a PCB with 
> an LPC2106 and FPGA on it. 
...
> the much easier to find Altera Cyclone EP1C3T100. I've ordered a few 

Do you have a feel for the power consumption of the FPGA?  I'm wondering
whether an FPGA would be feasible on an LPC2106 where low power (long
battery life) was a primary consideration.


-- 
Frank



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