Measure current
5.1 Use an oscilloscope for current measurements
An oscilloscope measures the voltage drop across a current-measurement resistor. Set up the EK and
oscilloscope according to the supply or output that you want to measure.
5.1.1 Prepare for VBAT current measurements
Mount a current-measurement resistor on the EK to measure the current on VBAT with an oscilloscope.
For VBAT current measurements:
• Mount an IBAT current-measurement resistor on R1. The recommended value is 100 mΩ or lower, to
avoid issues with the PMICs automatic trickle charge feature.
• Disconnect the jumper between VBAT and VBATIN.
• Use P1 pin 1 (VBATIN) and pin 2 (VBAT) as a probe points for performing VBAT current
measurements.
• Make sure the oscilloscope supports bidirectional measurements.
To restore the EK to default jumper settings after measurements, connect the jumper between VBAT and
VBATIN across pin 1 and pin 2 on P1 and demount the IBAT series resistor.
5.1.2 Prepare for VBUS and VOUT current measurements
To measure the current on VBUS, VOUT1, or VOUT2 with an oscilloscope, measure the voltage across an
external current-measurement resistor (not mounted).
For VBUS current measurement:
• Connect a suitable current-measurement resistor between the source and VBUS pin 1 on P2.
• Connect GND pin 4 on P2 to the source ground to ensure proper system grounding.
For VOUT1 current measurement:
• Connect a suitable current-measurement resistor between the load and VOUT1 pin 1 (or pin 2) on P4.
• Connect GND pin 3 (or pin 4) on P4 to the load ground to ensure proper system grounding.
For VOUT2 current measurement:
• Connect a suitable current-measurement resistor between the load and VOUT2 pin 1 (or pin 2) on P5.
• Connect GND pin 3 (or pin 4) on P5 to the load ground to ensure proper system grounding.
Note: It is recommended to use standard jumper wires compatible with 2.54 mm (0.1'') headers.
Make sure the jumper wires are rated for the high currents.
5.1.3 Measure VBAT, VBUS, and VOUT using an oscilloscope
Measure the current with an oscilloscope by probing the voltage drop across a current-measurement
resistor.
Make sure you have prepared the EK for the given oscilloscope measurement case, as described in Prepare
for VBAT current measurements on page 28 and Prepare for VBUS and VOUT current measurements
on page 28.
Measurement steps:
1. Connect an oscilloscope in differential mode (or a similar mode) with two probes across the probe
points of interest, depending on the measurement case prepared initially.
The following figure shows the VBAT current-measurement case, with probe points across the IBAT
resistor between pins 1 and 2 on P1.
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