
REF: BB_SRM_xM BeagleBoard-xM System
Reference Manual
Revision A2
Page 51 of 164
to 2.5V. In order to prevent the voltage levels from exceeding this value a pair of resistors
of 12K and 10K is used to scale the voltage down.
C83 0.1uF,10V
R52
10K,1%
C84 0.1uF,10V
R53 10K,1%
ADCIN5
ADCIN3
R48
12K,1%
R49
12K,1%
VBAT_FB
VBAT
R14
56.2K,1%
R15
22.6K,1%
C5
10uF,CER,0805,6.3V
DC_5V
4.2V
VBAT_MAIN
C7
0.1uF,10V
R13 .1,0805
+
J2
HDR2_.1x.1
1 2
U3
TL1963A
IN
2
SHDN
1
OUT
4
ADJ
5
GND
3
GND
6
U7A TPS65950
CTSI/BERDATA/ADCIN3
P11
RTSO/CLK64K/BERCLK/ADCIN5
N11
Figure 23. Processor Current Measurement
This results in a value that is 46% of the actual value. So, for a maximum value of 5.25V,
the voltage read would be 2.415V which keeps it below the 2.5V point. The voltage drop
across R13 will be small as the value of the resistor is 0.1 ohms. For every 100 mA of
current a voltage of .01V will be detected. In order to determine the actual power, the
input voltage and the voltage drop must be measured.
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