Seagate ST15150N Product Manual - Page 83

Input characteristics, Notes

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ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D 73 Differential voltage = 1.0V minimum with common-mode voltage ranges from −7V DC to +12V DC * Measure these voltages between the output terminal and the SCSI device's logic ground reference. The output characteristics must additionally conform to EIA RS-485-1983. Input characteristics Each signal received by differential interface drives should have the following input characteristics when measured at the disc drive's SCSI connector: Input current on either input = +2.0 milliamps maximum (includes both receivers and passive drivers) This requirement is met with the input voltage varying between −7V DC and +12V DC, with power on or off, and with the hysteresis equaling 35 mV minimum. The input characteristics must additionally conform to EIA RS-485-1983. +5V +5V 5.6K Transmit/Receive Enable [1] DE LSI RE XCVR Transmit or Receive Signal [2] 1 1 R2 [3] [4] Figure 32. Typical differential I/O line transmitter/receiver and terminators Notes: [1] Positive logic enables transmitter (+5V = asserted). Negative logic enables receivers (0V = asserted). [2] Negative logic signal (0V = asserted). [3] Total interface cable length should not exceed 82.1 feet (25 meters) from the host to the end of the daisy chain. [4] Terminators must be provided by user where needed.

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ST15150N/ND/W/WD/WC/DC Product Manual, Rev. D
73
Differential voltage
= 1.0V minimum with common-mode voltage ranges
from
-
7V DC to
+
12V DC
* Measure these voltages between the output terminal and the SCSI
device’s logic ground reference.
The output characteristics must additionally conform to EIA RS-485-1983.
Input characteristics
Each signal received by differential interface drives should have the following
input characteristics when measured at the disc drive’s SCSI connector:
Input current on either input
=
+
2.0 milliamps maximum
(includes both receivers and passive drivers)
This requirement is met with the input voltage varying between
-
7V DC and
+
12V DC, with power on or off, and with the hysteresis equaling 35 mV
minimum.
The input characteristics must additionally conform to EIA RS-485-1983.
Figure 32. Typical differential I/O line transmitter/receiver and terminators
Notes:
[1]
Positive logic enables transmitter (
+
5V = asserted).
Negative logic enables receivers
(0V = asserted).
[2]
Negative logic signal (0V = asserted).
[3]
Total interface cable length should not exceed 82.1 feet (25 meters)
from the host to the end of the daisy chain.
[4]
Terminators must be provided by user where needed.
DE
RE
LSI
XCVR
1
1
R
2
+5V
+5V
5.6K
Transmit/Receive
Enable
[1]
Transmit or
Receive
Signal
[2]
[3]
[4]