Seagate Pulsar XT.2 Manual download pdf (Page 67)

Pulsar XT.2 SAS Product Manual, Rev. B 59

11.4.6 SAS transmitters and receivers

A typical SAS differential copper transmitter and receiver pair is shown in Figure 17. The receiver is AC cou-

pling to eliminate ground shift noise.

Figure 17. SAS transmitters and receivers

11.4.7 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.

11.5 Signal characteristics

This section describes the electrical signal characteristics of the drive’s input and output signals. See Table 21

for signal type and signal name information.

11.5.1 Ready LED Out

The Ready LED Out signal is driven by the drive as indicated in Table 22.

Table 22: Ready LED Out conditions

Normal command activity LED status

Ready LED Meaning bit mode page 19h

Drive stopped, not ready, and no activity

Off Off

Drive stopped, not ready, and activity

(command executing)

On On

Drive started, ready, and no activity

On Off

Drive started, ready, and activity

(command executing)

Off On

Drive transitioning from not-ready state to

ready state or the reverse.

Blinks steadily

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

FORMAT UNIT in progress,

Toggles on/off

Receiver

Differential

Transfer Medium

.01

100100

Transmitter

1 2 ... 62 63 64 65 66 67 68 69 70 71 72 73 74

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Seagate Pulsar XT.2 Manual Page 67

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