Power Requirements; Environmental Requirements; Power Supply Dc Current Requirements - DEC AlphaPC 164 User Manual

2.1 Power Requirements

The AlphaPC 164 motherboard has a total power dissipation of 116 W, excluding
any plug-in PCI and ISA devices. Table 3 lists the power requirement for each dc
supply voltage.
The power supply must supply a DCOK signal to the system reset logic.
Table 3 Power Supply DC Current Requirements
Voltage/Tolerance
+3.4 V dc,
±
+5 V dc,
±
–5 V dc,
+12 V dc,
–12 V dc,
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Values indicated are for an AlphaPC 164 motherboard (64MB DRAM) excluding
adapter cards and disk drives.
Caution:

2.2 Environmental Requirements

The 21164 microprocessor is cooled by a small fan blowing directly into the chip's
heat sink. The AlphaPC 164 motherboard is designed to run efficiently by using only
this fan. Additional fans may be necessary depending upon cabinetry and the
requirements of plug-in cards.
The AlphaPC 164 motherboard is specified to run within the environment listed in
Table 4.
6 Features of the AlphaPC 164 Motherboard
Current
±
3% 5.0 A
5% 12.0 A
5% 0 A
±
5% 1.0 A
±
5% 100.0 mA
Fan Sensor Required
The 21164 microprocessor cooling fan must have a built-in sensor that
will drive a signal if the airflow stops. The sensor is connected to
motherboard connector J21. When the signal is generated, it resets the
system.
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