GE VP11, Reference Manual

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CHAPTER 4 Getting started
Chapter Scope
This chapter gives some useful tips when using a board from VR11 family the
first time. It might be also useful to read this chapter carefully, when problems
came up in using the VR11.
Power Supply
All boards of the VR11 family require up to 50 Watts from the power supply.
For exact values please check the current manual in chapter 8 'Specifications',
but for rough data a current of up to 7 A at the 5 V rail and 12 A at the 3.3 V
rail must be taken into consideration. The +12 V must only supply a few mA
and is not very critical. If there are harddisc or PMC modules attached to the
VR11, then their power consumption must also be calculated. Keep in mind
that standard power supplies often require minimum loads on every supply
voltage for proper operation. It might be necessary to add a load to the +12 V to
ensure correct voltage levels on 3.3 V and 5 V.
If you ever see the board not starting well or doing resets at random states,
please check the voltage of the three supply voltages at the backplane. When
measuring there, you can use a standard digital multimeter and you have to
attach it to the backplane at positions where no high current is flowing. So
better use rear contacts of the bus connectors or unused power connectors to
measure, because measuring the voltages at the used power connectors can
result in wrong values, which are caused by the high current flowing.
The +12 V are less critical, but 5 V and 3.3 V should reach their nominal value
when measuring with a multimeter. If the voltages are less than 5.0 V or 3.3 V,
then short voltage drops while the CPU or memory gets into high activities may
result in resetting the VR11 board.
GE Intelligent Platforms – VR11, VP11 Hardware Reference Manual, Second Edition Page 39