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Elite 23 Product Manual, Rev. A 21

Note. All times and currents are typical. See Table 2 for maximum current requirements.

6.3 Power dissipation

ST423451N/W

For drives with single-ended interface circuits, typical operating random read power dissipation is 24 watts

(82 BTUs per hour) of DC power average at nominal voltages.

ST423451WD

For drives with differential interface circuits, typical operating random read power dissipation is 25 watts

(85 BTUs per hour) of DC power average at nominal voltages.

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

The drive meets all specifications over a 41°F to 122°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 values. 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 an 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

these temperatures. See Section 8.3.1. Continual or sustained operation at case temperatures above these

values may degrade MTBF.

To confirm that the required cooling for the drive electronics and HDA is provided, place the drive in its final

mechanical configuration, perform random write/read operations and, after the temperatures stabilize, mea-

sure the case temperature of the components listed on the next several pages.

To obtain the maximum temperature for each of the reference components listed (Column 1), 27°F (15°C)

was added to the temperatures of Column 2. Operation of the drive at the maximum case temperature is

intended for short time periods only. Continuous operation at the elevated temperatures will reduce product

reliability.

T3 - The spindle is up to speed and the head-arm restraint is unlocked.

T4 - Heads move from the landing zone to the data area.

T5 - The adaptive calibration sequence is performed.

T6 - Calibration is complete and the drive is ready for reading and writing.

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