Current Drain Waveforms Yield Deeper Insights on Optimizing Battery Run Time

Gaining deeper insights into a mobile device’s operation is crucial for optimizing battery run time.

If you want to simply validate battery run time, you can treat the mobile device as a black box and either directly measure the run time or measure current drain for a prolonged period and extrapolate run time based on stated battery amp-hour capacity. Most conformance tests only validate battery run time.

However, optimizing battery run time usually requires the design team to use several different test methods to gain insights that go well beyond just validating battery run time. You need to test and characterize the device, its sub-circuits and the battery, both independently and in combination. A detailed characterization of battery current drain offers deeper insights into the device’s operation so you can make informed tradeoffs for optimizing run time.

High-speed, high-resolution current drain digitization yields deeper insights for optimizing battery run time.

Digitizing the battery current drain at 50 KSamples /second or greater and with a wide dynamic measurement range provides details yielding deeper insights for optimizing battery run time.

You can take a number of approaches, some of which have limitations:

• Current probes and oscilloscopes provide high-speed waveform digitization. However, limited dynamic range, inaccuracies, and noise limit their usefulness.
• A high-sampling-speed data acquisition system and an accurate current shunt can provide better accuracy and wider range compared to a current probe and oscilloscope. However, you must keep maximum tolerable current shunt peak voltage drop small so that it does not unduly affect the mobile device. However, keeping the shunt voltage drop small limits the measurement dynamic range and accuracy.
• Some specialized DC sources incorporate a high-speed digitizing, wide-dynamic-rangemeasurement system that can accurately characterize a mobile device’s current drain without the voltage drop issues you encounter when you use an external shunt resistor.