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AC Characteristics 6-9
6.3 AC Characteristics
The AC characteristics described in this section apply over the entire
range of operating conditions (refer to the DC Characteristics section).
Chip timings are based on simulation at worst case voltage, temperature,
and processing. Timing was developed with a load capacitance of 50 pF.
Table 6.1 2 and Figure 6.6 provide external clock timing data.
Figure 6.6 External Clock
Table 6.12 External Clock
1
1. Timings are for an external 40 MHz clock.
Symbol Parameter Min Max Unit
t
1
Bus clock cycle time 30 DC ns
SCSI clock cycle time (SCLK)
2
2. This parameter must be met to ensure SCSI timings are within specification.
25 60 ns
t
2
CLK LOW time
3
3. Duty cycle not to exceed 60/40.
10 – ns
SCLK LOW time
3
633ns
t
3
CLK HIGH time
3
12 – ns
SCLK HIGH time
3
10 33 ns
t
4
CLK slew rate 1 – V/ns
SCLK slew rate 1 – V/ns
CLK, SCLK 1.4 V
t
1
t
3
t
4
t
2