Seagate ST3146954FC, ST373554FC, ST336854FC manual Electrical description, Pin descriptions

9.5.3Electrical description

Fibre Channel drives use the FC-SCA connector for:

•DC power

•FC-AL interface

•Drive select (device identification)

•Option selection

•Enclosure Services interface

This 40-pin connector is designed to plug directly into a backpanel. External cables are not required.

9.5.4Pin descriptions

This section provides a pin-out of the FC-SCA and a description of the functions provided by the pins.

Table 24: FC-SCA pin descriptions

Pin	Signal name	Signal type
1*	-EN bypass port A	Low Voltage TTL output
2*	12 Volts
3*	12 Volts
4*	12 Volts
5*	-Parallel ESI
6*	Ground[1]
7*	Active LED out	Open collector out
8*	Reserved
9*	Start_1[2]	TTL input
10*	Start_2[2]	TTL input
11*	-EN bypass port B	Low Voltage TTL output
12*	SEL_6	TTL input/output
13*	SEL_5	TTL input/output
14*	SEL_4	TTL input
15*	SEL_3	TTL input/output
16*	Fault LED out	Open collector out
17*	DEV_CTRL_CODE_2[2]	TTL input
18*	DEV_CTRL_CODE_1[2]	TTL input
19*	5 Volts
20*	5 Volts

Pin	Signal name	Signal type
21	12 Volts charge
22	Ground
23	Ground
24*	+Port A_in	FC Diff. input pair
25*	-Port A_in
26	Ground
27*	+Port B_in	FC Diff. input pair
28*	-Port B_in
29	Ground
30*	+Port A_out	FC Diff. output pair
31*	-Port A_out
32	Ground
33*	+Port B_out	FC Diff. output pair
34*	-Port B_out
35	Ground
36	SEL_2	TTL input/output
37	SEL_1	TTL input/output
38	SEL_0	TTL input/output
39	DEV_CTRL_CODE_0[2	TTL input
40	5 Volts charge

*Short pins in mating backpanel connector.

[1]This pin may be connected to external logic to detect the presence of the drive. The drive connects this pin to the common ground.

[2]Pins 9, 10, 17, 18, and 39 are option select pins and are tied high by the drive circuitry. The preferred elec- trical connection at the backplane is either open or grounded (open for the ‘1’ setting, grounded for the ‘0’ setting). Alternatively, these pins may be driven by a 3.3V logic device, pulled up to 3.3V through a pull-up resistor (recommended size of 10k ohm), or grounded through some other means.

66 Cheetah 15K.4 FC Product Manual, Rev. B