Ac Electrical Specifications-Bus Arbitration - Motorola M68000 User Manual

10.12 AC ELECTRICAL SPECIFICATIONS — BUS ARBITRATION
VDC 5%; GND=0 VDC, T A =T L TO T H ; See Figure s 10-7 – 10-11) (Applies To All Processors
Except The MC68EC000)
Num Characteristic
7 Clock High to Address, Data
Bus High Impedance
(Maximum)
16 Clock High to Control Bus
High Impedance
33 Clock High to BG Asserted
34 Clock High to BG Negated
35 BR Asserted to BG Asserted
36 1
BR Negated to BG Negated
37 BGACK Asserted to BG
Negated
37A 2
BGACK Asserted to BR
Negated
38 BG Asserted to Control,
Address, Data Bus High
Impedance (AS Negated)
39 BG Width Negated
46 BGACK Width Low
47 Asynchronous Input Setup
Time
57 BGACK Negated to AS, DS ,
R/ W Driven
57A BGACK Negated to FC, VMA
Driven
58 1
BR Negated to AS , DS, R/ W
Driven
58A 1
BR Negated to FC, VMA
Driven
*These specifications represent improvement over previously published specifications for the 8-, 10-, and 12.5-MHz
MC68000 and are valid only for product bearing date codes of 8827 and later.
** Applies only to the MC68HC000 and MC68HC001.
NOTES:
1. Setup time for the synchronous inputs BGACK , IPL0 - IPL2 , and VPA guarantees their recognition at the
next falling edge of the clock.
2. BR need fall at this time only in order to insure being recognized at the end of the bus cycle.
3. Timing measurements are referenced to and from a low voltage of 0.8 volt and a high voltage of 2.0 volts,
unless otherwise noted. The voltage swing through this range should start outside and pass through the
range such that the rise or fall will be lienar between 0.8 volt and 2.0 volts.
4. The processor will negate BG and begin driving the bus again if external arbitration logic negates BR before
asserting BGACK.
5. The minimum value must be met to guarantee proper operation. If the maximum value is exceeded, BG may
be reasserted.
MOTOROLA M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL
Freescale Semiconductor, Inc.
8 MHz* 10 MHz*
Min Max Min
— 80 —
— 80 —
— 62 —
— 62 —
1.5 3.5 1.5
1.5 3.5 1.5
1.5 3.5 1.5
20 1.5 20
Clks
80
1.5 — 1.5
1.5 — 1.5
10 — 10
1.5 — 1.5
1 — 1
1.5 — 1.5
1 — 1
For More Information On This Product,
Go to: www.freescale.com
16.67 MHz
12.5 MHz*
12F
Max Min Max Min Max
70 — 60 — 50
70 — 60 — 50
50 — 40 0 40
50 — 40 0 40
3.5 1.5 3.5 1.5 3.5
3.5 1.5 3.5 1.5 3.5
3.5 1.5 3.5 1.5 3.5
1.5 20 1.5 10 1.5
Clks Clks Clks
70 60 — 50
— 1.5 — 1.5 —
— 1.5 — 1.5 —
— 10 — 5 —
— 1.5 — 1.5 —
— 1 — 1 —
— 1.5 — 1.5 —
— 1 — 1 —
(V CC =5.0
••
16 MHz 20 MHz Unit
Min Max Min Max
— 50 — 42 ns
— 50 — 42 ns
0 30 0 25 ns
0 30 0 25 ns
1.5 3.5 1.5 3.5 Clks
1.5 3.5 1.5 3.5 Clks
1.5 3.5 1.5 3.5 Clks
10 1.5 10 1.5 Clks/
Clks Clks ns
— 50 — 42 ns
1.5 — 1.5 — Clks
1.5 — 1.5 — Clks
5 — 5 — ns
1.5 — 1.5 — Clks
1 — 1 — Clks
1.5 — 1.5 — Clks
1 — 1 — Clks
10-17