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2.7
Isolated Current Measurement of the CC3220
To measure the current draw of the CC3220 when powering with a USB cable, use the VBAT jumper on
the jumper isolation block (J19). The current measured in this mode includes only the CC3220 current and
the serial flash current, and no external blocks. However, if a GPIO of the CC3220 is driving a high-current
load such as an LED, then that is also included in this measurement.
2.7.1
Low-Current Measurement With USB Power (< 1 mA)
To measure the current draw of the CC3220 MCU and serial flash using a ammeter, use the VBAT jumper
on the isolation block. Follow these steps to measure ultra-low power operation of the CC3220:
1. Remove the VBAT jumper (J19) in the isolation block; attach an ammeter across this jumper, as shown
in
Figure
19.
2. Consider the effect that the backchannel UART and any circuitry attached to the CC3220 may have on
current draw. Considering disconnecting these at the isolation jumper block, or at least consider their
sinking and sourcing capability in the final measurement. The CC3220 device should not drive any
high-current loads directly (such as an LED) because this can draw a large current.
3. Ensure that there are no floating inputs/outputs (I/Os) on the CC3220. These cause unnecessary extra
current draw. Every I/O should either be driven out or, if it is an input, should be pulled or driven to a
high or low level.
4. Begin target execution and set the device to low-power modes (LPDS or hibernate).
5. 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.
More information on how to experience the low-power modes and test cases of the CC3220 LaunchPad
kit can be found in the
Power Management
NOTE: Placing the CC3220 device in shutdown mode causes an approximately 33-μA leak into the
pull-up resistor (R136) on the nRESET pin. This pull-up resistor must also be removed to
measure the total current below 1 µA in shutdown mode.
SWRU463C – February 2017 – Revised March 2020
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Figure 19. Low-Current Measurement (<1 mA)
CC3120, CC3220 SimpleLink™ Wi-Fi® Internet-on-a chip™ Networking Subsystem
(see the Power Measurement Guide section).
CC3220 SimpleLink™ Wi-Fi
Copyright © 2017–2020, Texas Instruments Incorporated
Hardware Description
®
LaunchPad™ Development Kit Hardware
23
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