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OEM FUNCTIONAL SPECIFICATION ULTRASTAR XP (DFHC) SSA MODELS 1.12/2.25 GB - 1.0" HIGH
2.2.4 CxB Models
The carrier models include a DC/DC power converter, device activity and fault/service indicators. There is
no additional current required for + 5V or +12V.
2.2.4.1 Power supply methods
When +38V is applied to the interface connector pins +38V Source A, +38V Source B, and Ground, the
+ 38V supply is input to a DC/DC converter that provides +12V and + 5V to the drive electronics.
2.2.4.2 DC/DC Converter
Typical efficiency of this converter is 80% at maximum output load with input voltage at 38V.
There are two independent +38V power supply inputs on the interface connector which supply two inde-
pendent inputs to the DC/DC converter, +38V Source A and +38V Source B (refer to Table 12 on
page 65). The DC/DC converter will operate while one input voltage is in the range of +34V to +40V and
the other input voltage is in the range of 0 to + 40 volts. Input voltage ripple must be less than 1.0 volts
peak-to-peak at the fundamental frequency of 420 Hz maximum, less than 500mv at the frequency from
421hz to 1 khz, less than 100mv at the frequency greater than 1 khz. The converter output is + 5 volts at
0.3 amps to 2.6 amps and +12 volts at 0.3 amps to 1.4 amps continuous current. The +12v output can
handle a surge current of 2.2 amps in 9 seconds.
The total input current to the converter is 1.6A amps when the highest input voltage on the power supply
input pins is +3 4 volts and the converter outputs are operating at full load. The input current ripple, due to
converter switching is no more than 100 milliamps peak-to-peak at 1 MHz Maximum inrush current is
limited to 3 amps during turn on except for a maximum period of 2 microseconds (during hot plugging)
where the current can exceed 3 amps but is less than 8 amps.
A DC/DC converter output enable is provided on the interface connector. This signal, +DC/DC Enable,is
pulled up within the converter. To enable the DC outputs, this line must be at or above 2.4 volts. To
disable the DC outputs, the signal must be at or below 1.4 volts.
The DC/DC converter has over-current, over-voltage, and over-temperature detection. Any of these condi-
tions will latch off the converter. The latch is reset by insuring that both input voltages fall below + 5 volts
for a period greater than or equal to 10 milliseconds.
Refer to 5.5, “Option Pins and Indicators” on page 66 for descriptions of the Early Power Off Warning and
Loss of Redundancy fault signals associated with the +38V supply inputs.
Source filename=POWER IBM Corporation Page 33 of 87