Single-Ended Transmitters And Receivers - Seagate Barracuda ST12550W Product Manual

Barracuda 1 and 2 Product Manual, Rev. C
11.7.3.2
Line Driver
Transmitter
[4]
(or transceiver)
[1]
[2]
Figure 25. Single-ended transmitters and receivers
Notes:
[1] Part of active terminator circuits. Enable drive termination when it is first
or last on the daisy chain.
Interface signal levels and logical sense at the drive I/O connector are
defined as follows:
Logic level Driver output
Negated (0)
Asserted (1)
The difference in the voltages between input and output signals is due to
losses in the cable.
[2] ANSI SCSI compatible circuits.
[3] Total interface cable length should not exceed that specified in Section
11.7.1.2.1.
[4] Source of drive terminator power is VR1 which has an input source
voltage selected by a jumper.
Differential drivers and receivers
Typical differential driver and receiver circuits used by ST11950ND,
ST11950WD, ST12550ND and ST12550WD drives are shown in Figure 26.
The differential drives have no provisions for terminator circuits.
Differential signals
All differential interface signals consist of two lines denoted SIGNAL
and –SIGNAL. A signal is true when
–SIGNAL, and a signal is false when –SIGNAL is more positive than
SIGNAL. Terminate all assigned signals at each end of the cable as
shown in Table 14. You must provide external termination for the differential
drives.
Output characteristics
Each signal driven by differential interface drives should have the following
output characteristics when measured at the disc drive's SCSI connector:
Low-level output voltage*
= 2.0V maximum at low-level output current
= 55 milliamps
[4]
+2.85V
Flat
110
Cable
[1]
Ohm
Pair
[3]
Receiver input
2.5V : 5.25V 2.0V : < 5.25V
0.4V : 0.0V 0.8V : > 0.0V
SIGNAL is more positive than
Line Receiver
Receiver
+2.85V
110
Ohm
[2]
67