Power consumption of embedded and IoT devices is getting reduced day by day. It is quite challenging to reduce the power consumption without measuring the dc current and energy properly.
Are DC current energy analyzers/power profilers available?
There are only a handful of devices available in the market which can help you easily analyze and estimate how much power embedded device is consuming at different stages of operations and over the period of time how much energy it is consuming.
This analysis becomes even more critical if you are building a device which will be powered by battery or will have some kind of power back up.
Many of the engineers still uses the traditional approach of the series shunt resistor or multimeter based current measurement, which doesn’t gives accurate results. Why? because in a typical embedded system design, the current requirement changes from time to time at a very fast rate. It’s hard to measure those dynamic current.
If you don’t have a very fast sampling frequency high precision DC current meter with PC interface and custom software, it will be very hard to do the analysis.
Even if you could do that, you will need voltage measurement and then energy calculation for each measurement. Ideally you need a measurement device with can give you atleast voltage, current, and computed energy readings on a running graph plot. With the help of graph plot it will be much easier to understand how the current consumption of embedded product is changing based on state of it operation and then hardware and firmware engineers can optimize the power consumption.
New Approach in 2021
Fortunately, there are two companies who has designed such a product to help engineers
Let’s talk to about them one by one in some details.
Joule scope measures current from nanoamps to amps while simultaneously measuring voltage, power, and energy.
Joulescope will connect your power supply in series to do all the measurements. It can operate in multimeter mode where you can see all measurement readings and in oscilloscope mode where you can see current graphs.
The instrument is powered by USB and transfers all the data to PC software via USB 2.0 high speed interface. The PC software comes along with the instrument.
- -1V to 15V voltage range
- -1A to 3A current range, continuous (10A pulses)
- 1.5 nA resolution, equivalent to 32-bits of dynamic range
- 250 kHz bandwidth with 2 million samples per second, 14-bit, simultaneous current and voltage
- Rapid 1 μs switching between shunt resistors for seamless dynamic current measurement
- Computes power and total energy
- Sensor ports electrically isolated from USB
- Works with Microsoft® Windows®, Apple® Mac® OS X®, and Linux®
For more details, please read the user guide.
Otii Arc is truly versatile. It is a 2 quadrant source measure unit (SMU) with a constant voltage or constant current source and sink together with a high precision multichannel multimeter. Set it up as a constant, linear power supply or a battery of your choice (with Otii Battery Toolbox).
Use it as a power analyzer or profiler to record and display real-time currents, voltages and/or UART logs. It provides nA resolution current measurements with a sample rate of upto 4ksps.
Otii Arc measures 10,9cm x 14,4cm x 4,4cm (WxLxH) and weighs 450 grams and the PC software works on Linux, Mac and Windows platforms.
You can power it by USB for portability, or by using an external DC-adapter.
It can measure the voltage upto 5.0V(MAX) with an accuracy of ±(0.1% + 1.5 mV) with sampling rate of 1ksps.
Current Measurement(0 – 2.5A, 5.0A peak) Accuracy is ±(0.1% + 50 nA) for upto +-19mA, above that the accuracy is ±(0.1 % + 150 µA).
Please go through the technical spec carefully before taking a purchase decision.
3. Nordic Semiconductor Power Profiler Kit 2 (PPK2 – 89$)
4. ZS-2102-A IOT Power Profiler (649$)
5. Battlab One Battery Life Optimizer (99$)
I hope you have found this information useful.
You can read my other interesting blogs & articles on embedded system design here.
I help embedded engineers and start ups build reliable and successful embedded products. If you need any help please let me know here.
Happy Learning to you!