The power budget
Generated by generators/p32power.py (D69) from every card's netlist — edit the generator, not this file.
Every card's +5 V current: typical (the datasheets' typical figures, or
our estimate at the bus clock) and maximum (each part at its datasheet
maximum and fastest rated frequency, all at once: an upper bound that is
never reached together). Parts behind a card's 3.3 V regulator count at
5 V (a linear regulator passes its current through). Rows marked
estimate have no datasheet figure yet; the Tang Nano 20K and the Picos
are to measure.
CMOS logic (74HCT, HC, ACT, LVC) draws microamps standing still; its
current is switching: C_pd × V × f for each gate and its loads, and
HCT's extra current for an input between the rails (a GAL's or TTL's
high). Estimated as 1 mA a chip at the bus clock (4 mA at most), 4 mA a
chip for ACT on the dot or capture clock (10 mA at most).
The cards
| Card |
Typical |
Maximum |
The largest share |
| CPU |
4.45 A |
7.82 A |
35 × GAL: 4.55 A at most |
| MMU / data |
1.79 A |
3.37 A |
7 × CY7C199: 1.08 A at most |
| memory |
0.31 A |
0.79 A |
3 × GAL: 0.39 A at most |
| I/O |
2.28 A |
3.90 A |
16 × GAL: 2.08 A at most |
| disk |
1.79 A |
2.86 A |
15 × GAL: 1.95 A at most |
| video |
1.16 A |
2.28 A |
5 × GAL: 0.65 A at most |
| debug |
3.17 A |
5.97 A |
24 × CY7C199: 3.72 A at most |
| backplane |
5 mA |
79 mA |
the +5V LED and the supervisor; the pull-ups with every pulled line low |
The machine
| Machine |
Typical |
Maximum |
| every card, 1 memory card |
15.0 A |
27.1 A |
| every card, 4 memory cards |
15.9 A |
28.7 A |
Wired from the supply directly, not through the backplane, but from the same +5 V rail (D78):
| Drives |
Typical |
Maximum |
| 2 CompactFlash cards (in CF-to-IDE adapters) |
0.2 A |
0.4 A |
| 2 IDE hard drives, 3.5" (their +5 V; +12 V for the motor) |
1.0 A |
1.6 A |
The supply (D78): a dedicated +5 V supply on the backplane's M4
bolts. The full machine (four memory cards) is 16 A typical, 29 A at
most on +5 V; with its drives on the same rail, 17 A typical, 31 A
at most. So 30 A at least, 40 A recommended: the worst case adds every
part's datasheet maximum, which never happen together, but a cheap
supply sags near its rating. The drives' +12 V (the hard drives' motors)
comes from the supply's own 12 V rail or a second, 12 V supply; it is
not on the backplane.
The connectors carry it: each card has 32 VCC and 60 GND pins (DIN
41612 contacts, rated 1–2 A each), against the largest card's 7.8 A at
most. The backplane takes its 29 A at most on two pairs of M4 bolts
(+5V and GND, one pair at each end, 10 AWG wire), about half each.
The 3.3 V regulators (LD1117V33, 800 mA, TO-220): the CPU card's
feeds the ALU's 74LVC latches and buffers (tens of mA); the I/O card's
the WIZ850io (132 mA) and its 3.3 V buffers, about 150 mA: 0.25 W in the
regulator, no heatsink needed. The Picos and the Tang Nano make their
own 3.3 V from 5 V.
Where the current goes: the GALs (ATF22V10C, about 85 mA each,
whether they switch or not) are 7.5 A of the 15.9 A typical. Microchip's
quarter-power and zero-power 22V10s (CQ, CQZ) draw a fraction of that
but are slower (15–20 ns); which GALs could take them is a question for
the timing pass against the datasheets (backlog).
The CPU card
| Part |
Count |
Typical |
Maximum |
Source |
| GAL |
35 |
2.98 A |
4.55 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| CY7C199 |
8 |
0.64 A |
1.24 A |
datasheet: max: CY7C199-15 at 1/tRC (66 MHz); typ: the CY7C199D's specified maximum |
| 74F283 |
8 |
0.29 A |
0.44 A |
estimate: the F family's adders |
| TANG_NANO_20K |
1 |
0.10 A |
0.30 A |
estimate: the ALU bitstream, SDRAM idle, the BL616: to measure |
| SST39SF010A |
9 |
90 mA |
0.27 A |
datasheet: read; standby 30 uA typ (max read to confirm on the datasheet) |
| 74ACT574 |
16 |
64 mA |
0.16 A |
estimate: switching at 12.5-24 MHz |
| 74ACT541 |
12 |
48 mA |
0.12 A |
estimate: switching at 12.5-24 MHz |
| 74ABT377 |
4 |
20 mA |
0.12 A |
datasheet: 30 mA with its outputs low |
| 74F153 |
4 |
48 mA |
80 mA |
datasheet |
| 74HCT541 |
16 |
16 mA |
64 mA |
estimate: switching at the bus clock |
| 74LVC574 |
13 |
13 mA |
52 mA |
estimate: switching at the bus clock, 3.3 V |
| 74ACT157 |
4 |
16 mA |
40 mA |
estimate: switching at 12.5-24 MHz |
| 74HCT157 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| 74HCT257 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| 74HCT153 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| 74HCT161 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| OSC24M |
1 |
15 mA |
30 mA |
estimate: a DIP-14 can oscillator |
| 74ACT32 |
3 |
12 mA |
30 mA |
estimate: switching at 12.5-24 MHz |
| OSC32M |
1 |
15 mA |
30 mA |
estimate: a DIP-14 can oscillator |
| 74HCT377 |
5 |
5 mA |
20 mA |
estimate: switching at the bus clock |
| 74F138 |
1 |
13 mA |
20 mA |
datasheet |
| 74ACT08 |
2 |
8 mA |
20 mA |
estimate: switching at 12.5-24 MHz |
| 74HCT253 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74HCT4002 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| LED |
3 |
9 mA |
15 mA |
estimate: with its resistor |
| 74HCT138 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| LD1117V33 |
1 |
5 mA |
10 mA |
datasheet: quiescent |
| 74HCT540 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74HCT574 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74LVC244 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock, 3.3 V |
| 74HCT148 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT00 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT14 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
4.45 A |
7.82 A |
|
The MMU / data card
| Part |
Count |
Typical |
Maximum |
Source |
| CY7C199 |
7 |
0.56 A |
1.08 A |
datasheet: max: CY7C199-15 at 1/tRC (66 MHz); typ: the CY7C199D's specified maximum |
| GAL |
8 |
0.68 A |
1.04 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| 74F161 |
8 |
0.30 A |
0.44 A |
datasheet: as the 74F163 |
| 74ABT377 |
7 |
35 mA |
0.21 A |
datasheet: 30 mA with its outputs low |
| 74F521 |
4 |
80 mA |
0.12 A |
estimate: the F family's comparators |
| 74ACT541 |
11 |
44 mA |
0.11 A |
estimate: switching at 12.5-24 MHz |
| 74HCT157 |
27 |
27 mA |
0.11 A |
estimate: switching at the bus clock |
| 74HCT541 |
24 |
24 mA |
96 mA |
estimate: switching at the bus clock |
| 74HCT253 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| 74HCT161 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| 74ACT157 |
2 |
8 mA |
20 mA |
estimate: switching at 12.5-24 MHz |
| 74HCT377 |
5 |
5 mA |
20 mA |
estimate: switching at the bus clock |
| 74HCT257 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74HCT138 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| 74ACT08 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| LED |
1 |
3 mA |
5 mA |
estimate: with its resistor |
| 74HCT00 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT32 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HC05 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
1.79 A |
3.37 A |
|
The memory card
| Part |
Count |
Typical |
Maximum |
Source |
| GAL |
3 |
0.26 A |
0.39 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| AS6C4008 |
32 |
40 mA |
0.24 A |
datasheet: one bank of 4 active (typ: a third of the cycles); the others deselected (4 / 50 uA) |
| SST39SF020A |
4 |
0 mA |
0.12 A |
datasheet: deselected after booting (30 uA); max: all four read |
| 74HCT245 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74HCT541 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| LED |
1 |
3 mA |
5 mA |
estimate: with its resistor |
| 74HCT138 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HC05 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
0.31 A |
0.79 A |
|
The I/O card
| Part |
Count |
Typical |
Maximum |
Source |
| GAL |
16 |
1.36 A |
2.08 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| SOCK2X8 |
2 |
0.22 A |
0.46 A |
estimate: a CH376S module (12 / 30 mA) and its USB drive (100 / 200 mA, the design's budget) |
| 74F163 |
8 |
0.30 A |
0.44 A |
datasheet |
| PICO |
1 |
60 mA |
0.30 A |
estimate: Pico 2 W: Wi-Fi on (peaks while sending) |
| WIZ850IO |
1 |
0.13 A |
0.15 A |
datasheet: 132 mA (WIZnet / DigiKey), through the LD1117 |
| 74LS145 |
9 |
63 mA |
0.12 A |
datasheet |
| MAX232A |
4 |
32 mA |
80 mA |
datasheet: 8 / 10 mA unloaded, plus two RS-232 loads |
| 74HCT540 |
12 |
12 mA |
48 mA |
estimate: switching at the bus clock |
| TL16C550 |
4 |
32 mA |
40 mA |
datasheet |
| 74HCT541 |
9 |
9 mA |
36 mA |
estimate: switching at the bus clock |
| OSC1M8432 |
1 |
10 mA |
20 mA |
estimate: a DIP-14 can oscillator |
| 74F138 |
1 |
13 mA |
20 mA |
datasheet |
| 74HCT245 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74HCT374 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| DS12C887 |
1 |
7 mA |
15 mA |
datasheet: max from the distributors' listings |
| 74HCT574 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| LD1117V33 |
1 |
5 mA |
10 mA |
datasheet: quiescent |
| 74HCT688 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74HCT14 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| LED |
1 |
3 mA |
5 mA |
estimate: with its resistor |
| 74HCT125 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74LVC244 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock, 3.3 V |
| 74HCT244 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HC05 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| CD74HC4050 |
1 |
1 mA |
2 mA |
estimate |
| total |
|
2.28 A |
3.90 A |
|
The disk card
| Part |
Count |
Typical |
Maximum |
Source |
| GAL |
15 |
1.27 A |
1.95 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| 74F163 |
12 |
0.44 A |
0.66 A |
datasheet |
| 74HCT541 |
20 |
20 mA |
80 mA |
estimate: switching at the bus clock |
| 74HCT245 |
13 |
13 mA |
52 mA |
estimate: switching at the bus clock |
| 74HCT574 |
10 |
10 mA |
40 mA |
estimate: switching at the bus clock |
| LED |
5 |
15 mA |
25 mA |
estimate: with its resistor |
| 74HCT540 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74LS145 |
1 |
7 mA |
13 mA |
datasheet |
| 74HCT688 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74HC05 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT153 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT85 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
1.79 A |
2.86 A |
|
The video card
| Part |
Count |
Typical |
Maximum |
Source |
| GAL |
5 |
0.42 A |
0.65 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| MINIDIN6F_RA |
2 |
0.10 A |
0.50 A |
estimate: a PS/2 device; both share the 0.5 A polyfuse |
| 74F299 |
4 |
0.27 A |
0.38 A |
estimate: the F family's shift registers; to confirm on the datasheet |
| AS6C1008 |
2 |
60 mA |
0.12 A |
estimate: taken as the AS6C4008's; to confirm on its datasheet |
| HD63484 |
1 |
60 mA |
0.10 A |
estimate: CMOS at 6.3 MHz: Hitachi's manual gives no figure; to measure |
| 27C256 |
2 |
20 mA |
60 mA |
estimate: an EPROM read all the time; to confirm on the datasheets (27C256, AT27C256R-70) |
| 74F163 |
1 |
37 mA |
55 mA |
datasheet |
| 74F74 |
3 |
33 mA |
48 mA |
estimate: the F family's flip-flops; to confirm on the datasheet |
| OSC25M |
1 |
15 mA |
30 mA |
estimate: a DIP-14 can oscillator |
| 74ACT32 |
3 |
12 mA |
30 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT574 |
3 |
12 mA |
30 mA |
estimate: switching at 12.5-24 MHz |
| 74LS145 |
2 |
14 mA |
26 mA |
datasheet |
| 74ACT573 |
2 |
8 mA |
20 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT245 |
2 |
8 mA |
20 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT273 |
2 |
8 mA |
20 mA |
estimate: switching at 12.5-24 MHz |
| ATMEGA328P |
1 |
10 mA |
20 mA |
estimate: active at 16 MHz, 5 V |
| 74F138 |
1 |
13 mA |
20 mA |
datasheet |
| 74HCT541 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| 74F21 |
2 |
8 mA |
16 mA |
estimate: the F family's gates; to confirm on the datasheet |
| 74ACT04 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT10 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT11 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT08 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT00 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT02 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT86 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT74 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74HCT245 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74HCT688 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| 74HCT574 |
2 |
2 mA |
8 mA |
estimate: switching at the bus clock |
| LED |
1 |
3 mA |
5 mA |
estimate: with its resistor |
| 74HCT244 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT74 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HC05 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
1.16 A |
2.28 A |
|
The debug card
| Part |
Count |
Typical |
Maximum |
Source |
| CY7C199 |
24 |
1.92 A |
3.72 A |
datasheet: max: CY7C199-15 at 1/tRC (66 MHz); typ: the CY7C199D's specified maximum |
| GAL |
6 |
0.51 A |
0.78 A |
datasheet: ATF22V10C-7 / -10, ICC (commercial) |
| 74F161 |
8 |
0.30 A |
0.44 A |
datasheet: as the 74F163 |
| TIL311 |
2 |
0.21 A |
0.36 A |
datasheet: a hex display: its logic 60 / 90 mA and its LEDs 45 / 90 mA (TI SODS001D) |
| 74ACT574 |
22 |
88 mA |
0.22 A |
estimate: switching at 12.5-24 MHz |
| 74HCT541 |
27 |
27 mA |
0.11 A |
estimate: switching at the bus clock |
| 74HCT574 |
19 |
19 mA |
76 mA |
estimate: switching at the bus clock |
| PICO |
1 |
25 mA |
60 mA |
estimate: Pico 2: USB to the Mac |
| 74HCT157 |
8 |
8 mA |
32 mA |
estimate: switching at the bus clock |
| OSC24M |
1 |
15 mA |
30 mA |
estimate: a DIP-14 can oscillator |
| 74HCT273 |
7 |
7 mA |
28 mA |
estimate: switching at the bus clock |
| 74HCT154 |
4 |
4 mA |
16 mA |
estimate: switching at the bus clock |
| LED |
3 |
9 mA |
15 mA |
estimate: with its resistor |
| 74HCT08 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| 74HC05 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| 74HCT138 |
3 |
3 mA |
12 mA |
estimate: switching at the bus clock |
| 74ACT157 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT00 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT04 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74ACT74 |
1 |
4 mA |
10 mA |
estimate: switching at 12.5-24 MHz |
| 74LVC245 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock, 3.3 V |
| 74HCT32 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| 74HCT74 |
1 |
1 mA |
4 mA |
estimate: switching at the bus clock |
| total |
|
3.17 A |
5.97 A |
|