SN74ACT2227, SN74ACT2229

DUAL 64

× 1, DUAL 256 × 1

FIRST-IN, FIRST-OUT MEMORIES

SCAS220C – JUNE 1992 – REVISED OCTOBER 1997

11

POST OFFICE BOX 655303

TYPICAL CHARACTERISTICS

0

5

10

15

20

25

30

35

40

0

102030405060

SINGLE FIFO SUPPLY CURRENT

vs

CLOCK FREQUENCY

fclock – Clock Frequency – MHz

fI = 1/2 fclock

TA = 75°C

CL = 0 pF

VCC = 5.5 V

VCC = 5 V

VCC = 4.5 V

Figure 5

calculating power dissipation

Data for Figure 5 is taken with one FIFO active and one FIFO idle on the device. The active FIFO has both writes

and reads enabled with its read clock (RDCLK) and write clock (WRTCLK) operating at the rate specified by

close approximation to the total device power can be found by Figure 5, determining the capacitive load on the

data output and determining the number of SN74ACT2227/2229 inputs driven by TTL high levels.

SN74ACT2229 can be calculated by:

where:

N

=

number of inputs driven by TTL levels

dc

=

duty cycle of inputs at a TTL high level of 3.4 V

=

output capacitive load

=

switching frequency of an output