Answers Database
CPLD: XC9500/XL : Power estimation for the 9500/XL family devices
Record #2653
Product Family: Hardware
Product Line: 9500
Product Part: 9500
Problem Title:
CPLD: XC9500/XL : Power estimation for the 9500/XL family devices
Problem Description:
Urgency: standard
General Description:
How can I estimate the power consumption of
my 9500/XL device?
Solution 1:
For XC9500:
The following equation is in the datasheet for each of the
9500 devices in the family.
Icc (mA) = MChp*(1.7) + MClp*(0.9) + MC(0.006 mA/MHz) f
Icc = operating current
MChp = macrocells in high performance mode
MClp = macrocells in low-power mode
MC = total number of macrocells used
f = clock frequency in MHz
The power dissipation in a 9500/XL device is completely dependent
on the pattern in the device and the state of its I/Os. The
above mentioned equation is only an approximate way of
calculating the operating current in the device and will not
always work very well. The equation also assumes that the
design has only one master clock operating at a frequency 'f'
and driving all the macrocells that are being used.
For example, if you have a 16 bit counter operating at 50 MHz
in high performance mode, then the value for Icc for a 9536
would be as follows :
Icc = 16*(1.7) + 20*(0.9) + 16*(0.006)*50 mA = 50.0 mA.
The same counter operating in low power mode at the same clock
speed would yield an Icc = 37.2 mA.
However, if your design has 2 4 bit counters operating in high
performance mode at 50MHz and 75 MHz respectively, and a block
of combinational logic consisting of 8 macrocells switching at
10 MHz, then
Icc = 16*(1.7) + 20*(0.9) + 4*(0.006)*50 + 4*(0.006)*75 +
8*(0.006)*10 mA = 48.68 mA.
The same design operating in low power mode at the same clock
speed would give an Icc = 35.88 mA.
This equation should not be used as a definite projection of
power consumption, but as an approximation.
Solution 2:
For XC9500XL:
There is a more detailed discussion on power consumption in
the following application note :
http://www.xilinx.com/xapp/xapp114.pdf
End of Record #2653 - Last Modified: 12/29/99 13:36 |
