OR3T125 Agere Systems, OR3T125 Datasheet - Page 147

• Manufacturer Part Number: OR3T125
• Description: 3C and 3T Field-Programmable Gate Arrays
• Manufacturer: Agere Systems

Data Sheet
June 1999
Estimating Power Dissipation
OR3Txxx (Preliminary Information)
The total operating power dissipated is estimated by
summing the standby (I
power dissipated. The internal and external power is
the power consumed in the PLCs and PICs, respec-
tively. In general, the standby power is small and may
be neglected. The total operating power is as follows:
The internal operating power is made up of two parts:
clock generation and PFU output power. The PFU out-
put power can be estimated based upon the number of
PFU outputs switching when driving an average fan-out
of two:
For each PFU output that switches, 0.068 mW/MHz
needs to be multiplied times the frequency (in MHz)
that the output switches. Generally, this can be esti-
mated by using one-half the clock rate, multiplied by
some activity factor; for example, 20%.
The power dissipated by the clock generation circuitry
is based upon four parts: the fixed clock power, the
power/clock branch row or column, the clock power dis-
sipated in each PFU that uses this particular clock, and
the power from the subset of those PFUs configured as
synchronous memory. Therefore, the clock power can
be calculated for the four parts using the following
equations.
OR3T20 Clock Power
P
For a quick estimate, the worst-case (typical circuit)
OR3T20 clock power
OR3T30 Clock Power
P
For a quick estimate, the worst-case (typical circuit)
OR3T30 clock power
Lucent Technologies Inc.
= [0.38 mW/MHz
+ (0.045 mW/MHz/Branch) (# Branches)
+ (0.015 mW/MHz/PFU) (# PFUs)
+ (0.004 mW/MHz/PIO (# PIOs)]
= [0.53 mW/MHz
+ (0.061 mW/MHz/Branch) (# Branches)
+ (0.015 mW/MHz/PFU) (# PFUs)
+ (0.004 mW/MHz/PIO (# PIOs)]
P
P
PFU
T
=
= 0.068 mW/MHz
DDSB
2.92 mW/MHz.
3.98 mW/MHz.
P
PLC
), internal, and external
+
P
PIC
(continued)
OR3T55 Clock Power
P
For a quick estimate, the worst-case (typical circuit)
OR3T55 clock power
OR3T80 Clock Power
P
For a quick estimate, the worst-case (typical circuit)
OR3T80 clock power
OR3T125 Clock Power
P
For a quick estimate, the worst-case (typical circuit)
OR3T125 clock power
The power dissipated in a PIC is the sum of the power
dissipated in the four PIOs in the PIC. This consists of
power dissipated by inputs and ac power dissipated by
outputs. The power dissipated in each PIO depends on
whether it is configured as an input, output, or input/
output. If a PIO is operating as an output, then there is
a power dissipation component for P
P
input.
The power dissipated by an input buffer (V
0.3 V or higher) is estimated as:
The ac power dissipation from an output or bidirec-
tional is estimated by the following:
where the unit for C
OUT
. This is because the output feeds back to the
= [0.88 mW/MHz
+ (0.102 mW/MHz/Branch) (# Branches)
+ (0.015 mW/MHz/PFU) (# PFUs)
+ (0.004 mW/MHz/PIO (# PIOs)]
= [0.107 mW/MHz
+ (0.124 mW/MHz/Branch) (# Branches)
+ (0.015 mW/MHz/PFU) (# PFUs)
+ (0.004 mW/MHz/PIO (# PIOs)]
= [0.167 mW/MHz
+ (0.193 mW/MHz/Branch) (# Branches)
+ (0.015 mW/MHz/PFU) (# PFUs)
+ (0.004 mW/MHz/PIO (# PIOs)]
P
OUT
= (C
ORCA Series 3C and 3T FPGAs
P
L
IN
L
+ 8.8 pF) x V
= 0.09 mW/MHz
is farads, and the unit for F is Hz.
6.58 mW/MHz.
9.47 mW/MHz.
15.44 mW/MHz.
DD
2
IN
x F Watts
, as well as
IH
= V
DD
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