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.

Tabl e 6.12 and Figure 6.6 provide external clock timing data.

Figure 6.6 External Clock

Table6.12 External Clock1
1. Timings are for an external 40 MHz clock.
Symbol Parameter Min Max Unit
t1Bus 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
t2CLK LOW time3
3. Duty cycle not to exceed 60/40.
10 – ns
SCLK LOW time3633ns
t3CLK HIGH time312 – ns
SCLK HIGH time310 33 ns
t4CLK slew rate 1 V/ns
SCLK slew rate 1 V/ns
CLK,SCLK 1.4 V
t1t3
t4t2