Low-Current Measurement (<1 Ma) - Texas Instruments SimpleLink Wi-Fi LaunchPad CC3235 Series User Manual

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2.6 Isolated Current Measurement of the CC3235 Device
To measure the current draw of the CC3235 device when powering with a USB cable, use the VBAT
jumper on the jumper isolation block (J24). The current measured in this mode includes only the CC3235
device current and the serial flash current, and no external blocks. However, if a GPIO of the CC3235
device is driving a high-current load such as an LED, then that is also included in this measurement.
2.6.1 Low-Current Measurement With USB Power (<1 mA)
Follow these steps to measure ultra-low power operation of the CC3235 device:
1. Remove the VBAT jumper (J24) and attach an ammeter as shown in
should not drive any high-current loads directly (such as an LED) because this can draw a large
current.
2. Begin target execution and set the device to low-power modes (LPDS or hibernate).
3. Measure the current. If the current levels are fluctuating, it may be difficult to get a stable
measurement. It is easier to measure quiescent states.
NOTE: To measure the low-power numbers, remove the LEDs (D8, D9, and D10 onboard) by
removing the LED EN jumper (J27). Similarly, the shutdown mode leaks approximately 33 μA
into the pull-up resistor (R149) on the nRESET pin. This pull-up resistor must also be
removed to measure the total current below 1 µA in shutdown mode.
SWRU539 – January 2019
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Figure 16. Low-Current Measurement (<1 mA)
CC3235x SimpleLink™ Wi-Fi
Copyright © 2019, Texas Instruments Incorporated
Hardware Description
Figure 16. The CC3235 device
®
LaunchPad™ Development Kit (LAUNCHXL-
21
CC3235x)