The Internet Of Things (IOT) market is in great acceleration and we expect more than 20 billion IOT devices to be connected to the internet in the next 10 years. Most of the IOT devices are powered by small batteries and optimizing the battery life is one of the most critical challenges in this area.
In order to estimate the battery life of a product we need accurate battery model along with the actual current profile of the device. This is where the challenge lies. The current consumption profile of a typical IOT device is shown below.
We observe that the device is in its sleep state for most of the time where it consumes few uA. Typically < 10uA. It wakes up intermittently and performs some processing, transmission and receive operations which consume several hundred milli amps peak. It then enters the sleep state again. All these operations occur within few milli seconds. The rise times of the currents are only few micro seconds wide. A typical profile cycle can be several tens of minutes long. In some cases, where a re-chargeable battery is used, the current could be fed back into the battery and this also needs to be accounted.
Most of the multi-meters cannot respond to this fast transient currents due to bandwidth limitations. Some recent ones do have enhanced bandwidths and can respond in time but these have capture length limitations. Most can record only few seconds of data.
Another popular approach is to use an oscilloscope and a series resistor with the load. The resistor converts the current into a voltage and using a differential probe, the oscilloscope can display the current. But this has some major drawbacks. Most oscilloscopes do not have the required dynamic range to span the currents from say 10uA to A range. That is over 100dB dynamic range. Scopes usually max out at 60dB or 80dB. Again the capture length limitations apply here as well.
The Solution : ZS-2102-A IOT Power Profiler
The ZS-2102-A is a USB powered tool designed exactly for this application. The tool connects in series with the load and the battery and records the current profile in real-time.
It an measure currents from few uA to 1A on a single measurement range.
Has a step response time of < 2 mS and can measure fast current pulses.
It can also measure negative current to -1A which is useful in case of devices with battery charging.
Synchronizes with external digital IO which is very useful for differential power analysis.
Almost unlimited capture length as it streams the data to the HDD on the PC.
Free Software
The free software provided with the kit is used to control the device and for waveform analysis. It can perform an accurate battery life estimation from current profiles which are several minutes long.
Simple measurement setup
The measurement setup is extremely simple. Just connect Power Profiler in series, with the Device Under Test (DUT). Connect the reference GND and the USB cable, the tool is set to measure.
Measurement Example
As an example, we measure the power profile of a popular WiFi module.
Here are a few sample screenshots from the GUI. Below image shows the WiFi module performing a calibration. Note the amount of details which can be observed with this tool.
Next we measure some short transmit pulses with very fast rise times. Notice the step response is well below 2us.
Next we observe the in-rush current during the power on Reset. This current goes from almost zero to 1A in few micro seconds.
Summary
The ZS-2102-A combines the dynamic range of a multi-meter and the response time of an oscilloscope in a compact USB powered solution. It is an absolute must-have for an IOT hardware designer in order to optimize the battery size and power distribution circuits. A firmware developer can measure the power profile in order to fine tune the algorithms. It is also a handy tool for the application developer which provides an accurate estimate of the battery life.
Ordering information
The tool can be purchased at www.anglercircuits.com. We provide free shipping all over the world. Some early bird offers are available. Grab them before they disappear.
See Video Demo