SUPPLY CHAIN
Make Your Small Asset Tracker Last Longer
Anil Telikepalli, Managing Director, Nazzareno Rossetti, Analogue and Power Management Expert, and Simo Radovic, Applications Director, all with Analog Devices
Abstract
This design solution reviews a typical asset tracking solution and shows how the MAX3864x nanopower buck converter family, with its high efficiency and small size, enables longer battery life in small portables. New, low power data connections are sparking a proliferation of asset tracking solutions thanks to their low cost of deployment. The effects can be seen in multiple applications, particularly transportation and supply chain management.
In a typical application, a sensor provides updates from a given location, transmitting data about temperature, humidity, pressure, and motion. The sensor only needs to transmit small amounts of data, which results in higher coverage and ultra low power consumption, enabling far greater device longevity. The sensor’s battery must last from several weeks to a few years. Asset tracking, depending on the application, may require the deployment of several tracker devices. Accordingly, these asset tracker devices must also be small, portable, and cost-effective.
In this design solution, we discuss the power management challenges encountered by a typical battery-operated asset tracker device and show an example using a small, high efficiency buck converter.
Edge-to-Enterprise Communication
Figure 1 illustrates a typical tracking communication chain. The asset being tracked transmits the data via a beacon, which reaches a server through a dedicated cellular network. From here, the data reaches the enterprise portal for asset management and analytics.
Asset Tracking Networks
A new generation of beacons connects directly to dedicated cellular networks (LTE- M, NB-IoT), eliminating the use of Bluetooth to communicate with a gateway. These
Figure 1. Real-time GPS tracking.
technologies can be very different but are all characterised by low power consumption, enabling several years of battery life (Table 1).
Typical Asset Tracker System NB-IoT 180
LTE-M Bandwidth
Peak Data Rate
U/D Link Speed
Latency
Battery Life Voice
100 62.5 10
>10 No
1400 384
1000
100 10
Yes Table 1. Networks Characteristics
Figure 2 shows a typical asset tracker block diagram. The three-series alkaline battery
supplies a charge of 2000mAh. A step-down regulator powers the onboard controller, sensors, and radio.
Units kHz kbps Mbps ms Years
For demanding asset tracking applications, the system must last for a year on three alkaline batteries, drawing only 100µA in deep sleep, and transmitting 100mA once per day for about 2 minutes (Figure 3). While it is true that, depending on power level and other options supported in the LTE-M or NB-IoT asset trackers, currents can be higher, for our discussion, we will stick to the 100µA to 100mA range.
Figure 3. Asset tracker current profile. Figure 2. An asset tracker block diagram.
High use performance requires careful selection of each block for minimum power consumption. The buck regulator must be efficient over a wide range from 100µA to 100mA. For instance, a 4% average loss of efficiency by the buck converter translates into a field deployment reduction of about two weeks.
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FEBRUARY 2024 | ELECTRONICS FOR ENGINEERS
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