Seagate ST9500621SS ユーザーズマニュアル

Constellation.2 SAS Product Manual, Rev. H

67

A typical SAS differential copper transmitter and receiver pair is shown in Figure 16. The receiver is AC cou-
pling to eliminate ground shift noise. 

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. 

This section describes the electrical signal characteristics of the drive’s input and output signals. See Table 13 
for signal type and signal name information.

Ready LED Meaning bit mode page 19h

0

1

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

l

T

M

01

01

100

100

T

X

TX

T