Bluegiga DKBLE, User Manual

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Page 12 of 20
3 Measuring Current Consumption
Figure 10: Measuring the current consumption
The peak current consumption of the module is measured over 3 ohm resistor using an instrumentation
amplifier with a gain of 10. The instrumentation amplifier is powered from USB 5V line and the DC bias is from
the 3V3 LDO. Because the amplifier is powered from the USB VBUS, it can’t be used unless USB is
connected. If USB is not connected then the instrumentation amplifier must be turned off and by-passed using
the switch labeled
“CURRENT MEAS OFF<->ON to avoid excessive leakage current into the input of the
amplifier.
NOTE: Peak current measurement is not possible when the external DCDC is used
3R
A=10
-
+
Ref
3V3
Figure 11: TX current measurement amplifier
Connect an oscilloscope
here to measure the peak
currents of the module and
switch
on the current
measurement amplifier
To measure the peak
currents, the board must
be powered from the USB
Connect a multimeter to
measure the DC current of
the module or of the whole
board in total