a3p1000-1pqg208m Actel Corporation, a3p1000-1pqg208m Datasheet - Page 33

• Manufacturer Part Number: a3p1000-1pqg208m
• Description: Fpga Proasic 3 Family 1m Gates 130nm Cmos Technology 1.5v 208-pin Pqfp
• Manufacturer: Actel Corporation

Guidelines
Toggle Rate Definition
A toggle rate defines the frequency of a net or logic element relative to a clock. It is a percentage. If the
toggle rate of a net is 100%, this means that this net switches at half the clock frequency. Below are
some examples:
Enable Rate Definition
Output enable rate is the average percentage of time during which tristate outputs are enabled. When
nontristate output buffers are used, the enable rate should be 100%.
Table 2-21 • Toggle Rate Guidelines Recommended for Power Calculation
Table 2-22 • Enable Rate Guidelines Recommended for Power Calculation
Component
α
α
Component
β
β
β
1
2
3
1
2
•
•
The average toggle rate of a shift register is 100% because all flip-flop outputs toggle at half of the
clock frequency.
The average toggle rate of an 8-bit counter is 25%:
– Bit 0 (LSB) = 100%
– Bit 1
– Bit 2
– …
– Bit 7 (MSB) = 0.78125%
– Average toggle rate = (100% + 50% + 25% + 12.5% + . . . + 0.78125%) / 8
= 50%
= 25%
Toggle rate of VersaTile outputs
I/O buffer toggle rate
I/O output buffer enable rate
RAM enable rate for read operations
RAM enable rate for write operations
R e v i s i o n 0
Definition
Definition
Military ProASIC3/EL Low Power Flash FPGAs
Guideline
Guideline
12.5%
12.5%
100%
10%
10%
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