Seagate ST3500620SS Manual download pdf (Page 65)

Barracuda ES.2 SAS Product Manual, Rev. G 59

9.4.6 SAS transmitters and receivers

A typical SAS differential copper transmitter and receiver pair is shown in Figure 15. The receiver is AC cou-

pling to eliminate ground shift noise.

Figure 15. SAS transmitters and receivers

9.4.7 Power

The drive receives power (+5 volts and +12 volts) through the SAS device connector.

Three +12 volt pins provide power to the drive, 2 short and 1 long. The current return for the +12 volt power

supply is through the common ground pins. The supply current and return current must be distributed as

evenly as possible among the pins.

Three +5 volt pins provide power to the drive, 2 short and 1 long. The current return for the +5 volt power sup-

ply is through the common ground pins. The supply current and return current must be distributed as evenly as

possible among the pins.

Current to the drive through the long power pins may be limited by the system to reduce inrush current to the

drive during hot plugging.

9.5 Signal characteristics

This section describes the electrical signal characteristics of the drive’s input and output signals. See Table 12

for signal type and signal name information.

9.5.1 Ready LED Out

The Ready LED Out signal is driven by the drive as indicated in Table 13.

Table 13: Ready LED Out conditions

Normal command activity LED status

Ready LED Meaning bit mode page 19h

Spun down and no activity Off Off

Spun down and activity (command executing) On On

Spun up and no activity On Off

Spun up and activity (command executing) Off On

Spinning up or down Blinks steadily

(50% on and 50% off, 0.5 seconds on and off for 0.5 seconds)

Format in progress, each cylinder change Toggles on/off

Receiver

Differential

Transfer Medium

.01

100100

Transmitter

1 2 ... 60 61 62 63 64 65 66 67 68 69 70 ... 77 78

No comments

Seagate ST3500620SS Manual Page 65