
11-10
MC68349 USER'S MANUAL
MOTOROLA
11.7 AC TIMING SPECIFICATIONS (Concluded)
3.3 V or
5.0 V
16.78 MHz
25.16 MHz
Num.
Characteristic
Symbol
Min
Max
Min
Max
Unit
85
DSCLK Cycle
tDSCCYC
2—2—
CLKOUT
86
CLKOUT High to FREEZE Asserted
tFRZA
050
0
35
ns
87
CLKOUT High to FREEZE Negated
tFRZN
050
0
35
ns
88
CLKOUT High to IFETCH High Impedance
tIFZ
050
0
35
ns
89
CLKOUT High to IFETCH Valid
tIF
050
0
35
ns
NOTES:
(a) The 16.78-MHz @ 3.3 V
±0.3 V specifications are preliminary and apply to the MC68349V.
(b) The 16.78-MHz @ 5.0 V
±5% specifications are preliminary and apply to the MC68349.
(c) The 25.16 MHz @ 5.0 V
±5% specifications are preliminary and apply to the MC68349.
1.
All AC timing is shown with respect to 0.8 V and 2.0 V levels unless otherwise noted.
2.
This number can be reduced to 5 ns if strobes have equal loads.
3.
If multiple chip selects are used, the CS width negated (#15) applies to the time from the negation of a heavily
loaded chip select to the assertion of a lightly loaded chip select.
4.
These hold times are specified with respect to DS or CS on asynchronous reads and with respect to CLKOUT on
fast termination reads. The user is free to use either hold time for fast termination reads.
5.
If the asynchronous setup time (#47) requirements are satisfied, the DSACK≈ low to data setup time (#31) and
DSACK≈ low to BERR low setup time (#48) can be ignored. The data must only satisfy the data-in to CLKOUT
low setup time (#27) for the following clock cycle: BERR must only satisfy the late BERR low to CLKOUT low
setup time (#27A) for the following clock cycle.
6.
To ensure coherency during every operand transfer, BG will not be asserted in response to BR until after cycles
of the current operand transfer are complete and RMC is negated.
7.
In the absence of DSACK≈, BERR is an asynchronous input using the asynchronous setup time (#47).
8.
Specification #47A for 16.78 MHz @ 3.3 V
±0.3V will be 8 ns.
9.
During interrupt acknowledge cycles up to two wait states may be inserted by the processor between states S0
and S1.