Seagate ST12450W, Руководство по эксплуатации продукта

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ST12450W/WD Product Manual, Rev. A 43
10.2.1.2 Termination
The reference index signal (SSREF
+
) is terminated with a 2.21K ohm
resistor. Each single-ended drive has a terminator resistor located on the
main PCB. The terminator resistor is not removable and is always in the
circuit; however, you can disable termination by using a jumper option. See
Section 10.1. There is no provision for internal termination on differential
models. See Section 11.7.3.2. A diode prevents current from backfeeding.
10.2.1.3 Physical interface
The dimensions of the J5 connector mounted on the main PCB to intercon-
nect the drives are shown in Figure 16. It is a 12-pin, 6-position gold 2 mm
header type connector. Only pins 11 and 12 are used for connecting the
reference index signal cable, as shown in Figure 14. Pin 11 is SSREF+ and
pin 12 is ground.
Figure 16. J5 configuration select header specification
10.3 Grounding
Signal ground (PCB) and HDA ground are connected together in the
Barracuda 2, 2HP family drives—do not separate this connection. Maximiz-
ing the conductive contact area between HDA ground and system ground
may reduce radiated emissions. A bracket shield with tapped holes is
available to system integrators. This shield makes it easier to attach a braid
or similar high-frequency grounding device. If you do not want the system
chassis to be connected to the HDA/PCB ground, you must provide a
nonconductive (electrically isolating) method of mounting the drive in the
host equipment; however, this may increase radiated emissions and is the
system designer’s responsibility.
J5
Pin 1
.079
(2 mm)
.079
(2 mm)
.520
(13.2 mm)
.185
(4.7 mm)