11.4.6 Sas Transmitters And Receivers; 11.4.7 Power; Signal Characteristics; 11.5.1 Ready Led Out - Seagate ST2400MM0129 Product Manual

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 coupling to eliminate ground
shift noise.
TX
Transmitter
100
TY
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 supply 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 Section 11.4.5 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 the table below.
Table 18 Ready LED Out conditions
Normal command activity
Ready LED Meaning bit mode page 19h
Spun down and no activity
Spun down and activity (command executing)
Spun up and no activity
Spun up and activity (command executing)
Spinning up or down
Format in progress, each cylinder change
Seagate Enterprise Performance 10K HDD v9 Product Manual, Rev. D (Draft 2)
.01
Differential
Transfer Medium
.01
0
Off
On
On
Off
(50% on and 50% off, 0.5 seconds on and off for 0.5 seconds)
RX
Receiver
100
RY
LED status
1
Off
On
Off
On
Blinks steadily
Toggles on/off
64