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Savvio SAS Product Manual, Rev. D
61
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 23
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 24.
The Ready LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the
proper +3.3 volt supply through an appropriate current limiting resistor. The LED and the current limiting resis-
tor are external to the drive. See Table 25 for the output characteristics of the LED drive signals.
9.5.2 Differential signals
The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS
standard.
Table 24: Ready LED Out conditions
Normal command activity LED status
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
Table 25: LED drive signal
State Test condition Output voltage
LED off, high 0 V ≤ VOH ≤ 3.6 V -100 µA < I
OH
< 100 µA
LED on, low I
OL
= 15 mA 0 ≤ V
OL
≤ 0.225 V