Table 6.42 SCSI-2 Fast Transfers 10.0 Mbytes (8-Bit Transfers) or 20.0 Mbytes (16-Bit Transfers) 40 MHz Clock

Symbol

Parameter

Min

Max

Unit

 

 

 

 

 

t1

Send SREQ/ or SACK/ assertion pulse width

30

ns

 

 

 

 

 

t2

Send SREQ/ or SACK/ deassertion pulse width

30

ns

t1

Receive SREQ/ or SACK/ assertion pulse width

22

ns

 

 

 

 

 

t2

Receive SREQ/ or SACK/ deassertion pulse width

22

ns

t3

Send data setup to SREQ/ or SACK/ asserted

24

ns

 

 

 

 

 

t4

Send data hold from SREQ/ or SACK/ asserted

34

ns

 

 

 

 

 

t5

Receive data setup to SREQ/ or SACK/ asserted

14

ns

t6

Receive data hold from SREQ/ or SACK/ asserted

24

ns

Table 6.43 Ultra SCSI Transfers 20.0 Mbytes (8-Bit Transfers) or

40.0 Mbytes (16-Bit Transfers) Quadrupled 40 MHz Clock1, 2

Symbol

Parameter

Min

Max

Unit

 

 

 

 

 

t1

Send SREQ/ or SACK/ assertion pulse width

15

ns

t2

Send SREQ/ or SACK/ deassertion pulse width

15

ns

t1

Receive SREQ/ or SACK/ assertion pulse width

11

ns

 

 

 

 

 

t2

Receive SREQ/ or SACK/ deassertion pulse width

11

ns

 

 

 

 

 

t3

Send data setup to SREQ/ or SACK/ asserted

12

ns

t4

Send data hold from SREQ/ or SACK/ asserted

17

ns

 

 

 

 

 

t5

Receive data setup to SREQ/ or SACK/ asserted

6

ns

 

 

 

 

 

t6

Receive data hold from SREQ/ or SACK/ asserted

11

ns

 

 

 

 

 

1.Transfer period bits (bits [6:4] in the SCSI Transfer (SXFER) register) are set to zero and the Extra Clock Cycle of Data Setup bit (bit 7 in SCSI Control One (SCNTL1)) is set.

2.During Ultra SCSI transfers, the value of the Extend REQ/ACK Filtering bit (SCSI Test Two (STEST2), bit 1) has no effect.

6-56

Electrical Specifications

Page 294
Image 294
LSI 53C875A technical manual Symbol Parameter Min Max Unit