Figure 31. Single-Ended Transmitters And Receivers - Seagate ST15150N - Barracuda 4.3 GB Hard Drive Product Manual

72
11.7.3.2
ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D
Line Driver
Transmitter
(or transceiver)
[2]

Figure 31. 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) 2.5V : 5.25V
Asserted (1) 0.4V : 0.0V
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 the length 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/receivers
Typical differential driver and receiver circuits used by ST15150WD drives
are shown in Figure 32. 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 is more positive than SIGNAL,
and a signal is false when SIGNAL is more positive than SIGNAL. All
assigned signals must be terminated at each end of the cable. 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
High-level output voltage*
= 3.0V minimum at high-level output current
= 55 milliamps
Line Receiver
[4] [4]
+2.85V +2.85V
Flat
110 110
Cable
[1] [1]
Ohm Ohm
Pair
[3]
Receiver input
2.0V : < 5.25V
0.8V : > 0.0V
Receiver
[2]