LSI 53C875A technical manual AC Characteristics, External Clock1, Symbol Parameter Min Max Unit

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 6.12 and Figure 6.6 provide external clock timing data.

Table 6.12 External Clock1

Symbol	Parameter	Min	Max	Unit
t1	Bus clock cycle time	30	DC	ns
	SCSI clock cycle time (SCLK)2	25	60	ns
t2	CLK LOW time3	10	–	ns
	SCLK LOW time3	6	33	ns
t3	CLK HIGH time3	12	–	ns
	SCLK HIGH time3	10	33	ns
t4	CLK slew rate	1	–	V/ns
	SCLK slew rate	1	–	V/ns

1.Timings are for an external 40 MHz clock.

2.This parameter must be met to ensure SCSI timings are within specification.

3.Duty cycle not to exceed 60/40.

Figure 6.6 External Clock

CLK, SCLK 1.4 V

t1 t3

t4 t2

AC Characteristics 6-9