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Table 7.1
C/D
I/O
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
7.3
Electrical Requirements
7.3.1
SCSI interface
(1)
Driver and receiver
For the interface signal driver, an open-collector or tri-state buffer circuit that satisfies the
following output characteristics is used. All signals are negative logic (true = "L").
The receiver and non-driver of the SCSI device under the power-on state should satisfy the
following input characteristics on each signal.
Output characteristics
V
= 0.0 to 0.50 VDC (@ I
OL
V
= 2.5 to 5.25 VDC
OH
Input characteristics
V
= 0.0 to 0.80 VDC
IL
I
= –0.4 to 0.0 mA (@ V
IL
V
= 2.0 to 5.25 VDC
IH
I
= 0.0 to 0.1 mA (@ V
IH
Input hysteresis = 0.2 VDC min.
Input capacitance = 25
Note:
The SCSI device under the power-off state should satisfy the characteristics of I
Recommended circuit
Driver:
MB463 (Fujitsu) or SN7438 (TI) (Open-collector NAND gate)
Receiver: SN74LS240 or SN74LS19 (TI) (Schmitt trigger input inverter)
7 - 6
INFORMATION TRANSFER phase identification
MSG
DB7-0, P
0
Data
0
Data
0
Command (CDB)
0
Status
1
–
1
–
1
Message
1
Message
= 48 mA)
OL
= 0.5 VDC)
I
= 2.7 VDC)
I
F max.
P
C156-E097-01EN
Direction
Phase
INIT → TARG
DATA OUT
INIT ← TARG
DATA IN
INIT → TARG
COMMAND
INIT ← TARG
STATUS
–
not used
–
not used
INIT → TARG
MESSAGE OUT
INIT ← TARG
MESSAGE IN
and I
.
IL
IH
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