22 CR11*, CP11*, CT11* 6U CompactPCI® SBC
Publication No. HRMCR11 Rev. B.0
CHAPTER 4
Chapter Scope
Power Supply
Getting Started
This chapter gives some useful tips when
using
a board from the
CR!
I family
the first time
.
It might be also useful to read t
hi
s
chapter carefully, when
problems came up in using the
CR!
1.
All boards of the
CRll
family require up to 70 Watts from the power
s
upp
ly.
For exact values please check the actual datasheet, but for rough data a current
ofup to 7 A to
11
A a.t the
5
V rail and
10
A to
15
A at the 3
.
3 V rail must be
taken into co11Sidera
ti
o
11. The + 12 V must only supply a few 111A and is not very
critical.
If
there are
h
arddi
s
c or PMC 111odules attached to the CR! I, 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,
p
l
ease check the voltage of the three supply voltages at the baclq,lane. When
111easuring there, you can use a standard digital multimeter and you have to
attach it to the bac.1..-plane at positions where no high currents are flowing
.
So
better use rear contacts of the b
u
s
connectors or u
n
u
sed power cow1ectors to
111easure
,
because measuring the voltages at the used power cow1ectors 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 111easuring with a 111ultin1eter. 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 111ay
result in resetting the
CR!
I board
.
Status indicator, Postcode and Beeps
The CR! I fa111ily has a triple color LED at the front panel for a quick status
indica
t
or usage
.
TI1e possible colors are red, amber or green and the LED can
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