a1240a-pg132b Actel Corporation, a1240a-pg132b Datasheet - Page 12

• Manufacturer Part Number: a1240a-pg132b
• Description: Hirel Fpgas
• Manufacturer: Actel Corporation

can be combined with frequency and voltage to represent
active power dissipation.
E quiv al ent C apac it ance
The power dissipated by a CMOS circuit can be expressed by
Equation 1:
where:
C
V
F
Equivalent capacitance is calculated by measuring I
at a specified frequency and voltage for each circuit
component of interest. Measurements are made over a range
of frequencies at a fixed value of V
is frequency independent so that the results can be used over
a wide range of operating conditions. Equivalent capacitance
values are shown below.
CE Q Val ues f or Act el FP G A s
To calculate the active power dissipated from the complete
design, the switching frequency of each part of the logic must
be known. Equation 2 shows a piecewise linear summation
over all components that applies to all ACT 1, 1200XL,
3200DX, ACT 2, and ACT 3 devices. Since the ACT 1 family has
only one routed array clock, the terms labeled routed_Clk2,
dedicated_Clk, and IO_Clk do not apply. Similarly, the ACT 2
family has two routed array clocks, and the dedicated_Clk
and IO_Clk terms do not apply. For ACT 3 devices, all terms
will apply.
Power = V
(p * (C
+ (r
(r
(s
12
Modules (C
Input Buffers (C
Output Buffers (C
Routed Array Clock
Buffer Loads (C
Dedicated Clock Buffer
Loads (C
I/O Clock Buffer Loads
(C
EQ
CC
2
2
EQCI
* f
* C
1
* f
q2
EQCI
EQO
)
)
q1
routed_Clk2
= Equivalent capacitance in pF
= Power supply in volts (V)
= Switching frequency in MHz
EQCD
)
CC
+ C
routed_Clk1
* f
EQM
2
s2
* [(m * C
L
)
Power (uW) = C
) * f
)
)
EQCR
IO_Clk
EQI
EQO
p
+ 0.5 * (s
)
)
outputs
)
+ 0.5 * (q
)
]
EQM
* f
ACT 3
+ 0.5 * (q
1
10.4
m
6.7
7.2
1.6
0.7
0.9
* C
2
)
EQ
modules
* C
EQCD
* V
CC
EQCR
3200DX ACT 2 ACT 1
1200XL
1
CC
. Equivalent capacitance
11.6
23.8
N/A
N/A
* C
* f
5.2
3.5
+ (n * C
2
* f
s1
* F
EQCR
)
q2
dedicated_Clk
)
routed_Clk2
* f
EQI
12.9
23.8
N/A
N/A
5.8
3.9
q1
* f
)
routed_Clk1
n
)
CC
inputs
+
22.1
31.2
N/A
N/A
active
+
3.7
4.6
(1)
(2)
+
where:
m
n
p
q
q
r
r
s
s
C
C
C
C
C
C
C
f
f
f
f
f
f
f
m
n
p
q1
q2
s1
s2
1
2
1
2
1
2
EQM
EQI
EQO
EQCR
EQCD
EQCI
L
= Number of logic modules switching at f
= Number of clock loads on the first routed
= Number of clock loads on the second routed
= Fixed capacitance due to first routed array
= Fixed capacitance due to second routed array
= Fixed number of clock loads on the dedicated
= Fixed number of clock loads on the dedicated
= Equivalent capacitance of logic modules in pF
= Equivalent capacitance of input buffers in pF
= Equivalent capacitance of output buffers
= Equivalent capacitance of routed array clock
= Equivalent capacitance of dedicated array
= Equivalent capacitance of dedicated I/O clock
= Output lead capacitance in pF
= Average logic module switching rate in MHz
= Average input buffer switching rate in MHz
= Average output buffer switching rate in MHz
= Average first routed array clock rate in MHz
= Average second routed array clock rate in
= Average dedicated array clock rate in MHz
= Average dedicated I/O clock rate in MHz
= Number of input buffers switching at f
= Number of output buffers switching at f
array clock (all families)
array clock (ACT 2, 1200XL, 3200DX, ACT 3
only)
clock (all families)
clock (ACT 2, 1200XL, 3200DX, ACT 3 only)
array clock (ACT 3 only)
I/O clock (ACT 3 only)
in pF
in pF
clock in pF
in pF
(all families)
MHz (ACT 2, 1200XL, 3200DX, ACT 3 only)
(ACT 3 only)
(ACT 3 only)
n
m
p