Parallel SCSI Interface Product Manual, Rev. A ) 23
Table 7: Transmit SCSI bus data and information phase DT timing values
[1] SCSI bus timing values specified by the maximum transfer rate for the given range shall apply even if a
slower transfer rate within the given range is negotiated.
[2] See Section 2.6 for measurement points for the timing specifications.
[3] See Section 9.6 in the ANSI SCSI Parallel Interface-5 (SPI-5) specification for examples of how to calcu-
late setup and hold timing.
Note. Fast-160 and fast 320 SCSI devices shall not change timing parameters between training or reset
events.
Timing description Reference Type
Timing values for negotiated transfer rate in nanoseconds
unless otherwise noted
[1]
Fast-10 Fast-20 Fast-40 Fast-80
Fast-
160
Fast-
320
ATN transmit setup time
2.5.2 min 48.4 29.2 19.6 14.8 14 14
Flow control transmit hold time
2.5.15 min 38.4 19.2 9.6 4.8 14 14
Flow control transmit setup time
2.5.16 min 48.4 29.2 19.6 14.8 14 14
pCRC transmit hold time
2.5.19 min 38.4 19.2 9.6 4.8 N/A N/A
pCRC transmit setup time
2.5.20 min 48.4 29.2 19.6 14.8 N/A N/A
Transmit assertion period [2]
2.5.55 min 92 46 23 11.5 5.69 2.565
Transmit hold time [2] [3]
2.5.56 min 38.4 19.2 9.6 4.8 4.77 0.365
Transmit ISI compensation
2.5.57 max 1.0 0
Transmit negation period [2]
2.5.58 min 92 46 23 11.5 5.69 2.565
Transmit REQ(ACK) period toler-
ance
2.5.60 max 0.6 0.6 0.6 0.6 0.06 0.06
Transmit REQ assertion period
with P_CRCA transitioning
2.5.61 min 97.5 54 35.5 24 N/A N/A
Transmit setup time [2] [3]
2.5.59 min 38.4 19.2 9.6 4.8 1.48 -2.76
Transmitter skew
2.5.63 max N/A N/A N/A N/A
± 0.75 ± 0.75
Transmitter time asymmetry
2.5.64 max N/A N/A N/A N/A
± 0.25 ± 0.25
