Seagate ST300MP0104 - 512E ユーザーズマニュアル

S

EAGATE 

E

NTERPRISE 

P

ERFORMANCE 

15K HDD 

AND 

E

NTERPRISE 

T

URBO 

SSHD SAS P

RODUCT 

M

ANUAL

, R

EV

. B

 

 58

  

11.4.6 SAS transmitters and receivers
A typical SAS differential copper transmitter and receiver pair is shown in Figure 19. The receiver is AC coupling to eliminate  ground shift 

noise. 

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 supply is through t he 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 15 for signal t ype and signal 

name information.

11.5.1 Ready LED Out
The Ready LED Out signal is driven by the drive as indicated in Table 16.

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