.H 1 "FIREFOX RAM POWER"

This is a summary of the power requirements for the Firefox RAM board.

.H 2 "The RAM Array"

.H 3 "Stand-by Power"

.DL
.LI
Stand-by current - 5mA X 72 chips = 360 mA
.LI
Refresh current - ((65-5) mA X 72 chips)/(12 uS/.23 uS) = 83 mA
.LI
Total stand-by current - 443 mA (886 mA for a 4 Mbyte board)
.LE

.H 3 "Active Power"

.DL
.LI
Chip access - ((75-5) mA X 72 chips)/(1.4 uS/.23 uS) = 828 mA
.LI
Nibble accesses - 3 Accesses X ((60-5) mA X 72 chips)/(1.4 uS/.06 uS) = 509 mA
.LI
Total active power - 443 mA + 828 mA + 509 mA = 1780 mA (2223 mA for a 4 Mbyte
board)
.LE

An active RAM chip will draw (900 mA + 600 mA + (500/2) mA)/39 = 45 mA

.H 2 "NMOS Controller Power"

+5V(S) - 200 mA

+5V - 750 mA

The controller
will draw 30% more power when it is powered up at 0 degrees C.  This
will only be until it warms itself up.

.H 2 "TTL Power"

The TTL power was estimated by dividing the typical power by .8.

74AS243 - 11 parts X 60 mA = 660 mA (Assumes output is a 1 about 100 percent
of the time.)

74AS804 - 2 parts X 12 mA = 24 mA (Assumes output is 1 50% of the time)

Total TTL power (+5V) = 684 mA

For 4 Mbyte board add:

74AS2620 - 5 parts X 82 mA = 410 mA (+5V(S))

.H 2 "Other Power"

The back up clock and regulators take about 10 mA (+5V(S)).

.H 2 "Total Board Power"

.H 3 "2 Mbyte Board"

Stand-by (+5V(S)) - 443 mA + 10 mA + 200 mA = 653 mA = 3.3 watts

Active(+5V(S)) - 1780 mA + 10 mA + 200 mA = 1990 mA = 10 watts

+5V - 750 mA + 684 mA = 1434 mA = 7.2 watts

.H 3 "4 Mbyte Board"

Stand-by (+5V(S)) - 886 mA + 10 mA + 200 mA + 410 mA = 1506 mA = 7.5 watts

Active(+5V(S)) - 2223 mA + 10 mA + 200 mA + 410 mA = 2843 mA = 14.2 watts

+5V - 750 mA + 684 mA = 1434 mA = 7.2 watts

