Product manual

Barracuda 9 Product Manual, Rev. C 23
Figure 3. Typical Barracuda 9 drive +5 V and +12 V current profile
6.3 Power dissipation
ST19171N/W/WC
For drives with single-ended interface circuits, typical operating random read power dissipation is 14.7 watts
(50 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions
is 13 watts (44 BTUs per hour).
ST19171WD/DC
For drives with differential interface circuits, typical operating random read power dissipation is 15.7 watts
(54 BTUs per hour) of DC power average at nominal voltages. Typical power dissipation under idle conditions
is 13.6 watts (47 BTUs per hour).
6.4 Environmental limits
Temperature and humidity values experienced by the drive must be such that condensation does not occur on
any drive part. Altitude and atmospheric pressure specifications are referenced to a standard day at 58.7°F
(14.8°C). Maximum wet bulb temperature is 82°F (28°C).
6.4.1 Temperature
a. Operating
With cooling designed to maintain the case temperatures of Table 3, column 2, the drive meets all specifica-
tions over a 41°F to 113°F (5°C to 50°C) drive ambient temperature range with a maximum gradient of 36°F
(20°C) per hour. The enclosure for the drive should be designed such that the temperatures at the locations
specified in Table 3, column 1 are not exceeded. Air flow may be needed to achieve these temperature val-
ues (Section 8.3 and 8.3.1). Operation at case temperatures above these values may adversely affect the
drives ability to meet specifications.
The MTBF specification for the drive is based on operating at a local ambient temperature of 86°F (30°C).
Occasional excursions to drive ambient temperatures of 122°F (50°C) or 41°F (5°C) may occur without
impact to specified MTBF. To achieve the specified MTBF, the enclosure for the drive should be designed
such that the temperature values of Table 3, column 2 are not exceeded. Air flow may be needed to achieve
0.0 2 4 6 8 10 12
0.0
0.5
1.0
1.5
2.0
2.5
3.0
T0 T2
Min AC
Peak DC
Peak AC
TIME (S)
+12V CURRENT (A)
T1 T3