From emerging applications in smart homes, wearables and building automation; battery-powered wireless applications represent one of the fastest-growing segments within IoT. This trend is driven by the need to eliminate all hardwires, either for connectivity or for power, which tend to limit their adoption. Remote sensing for agriculture and industrial, smart cities and wearables are but a few examples that would not be possible without the flexibility and ease of adoption battery power provides over wired or wall-powered solutions.
One obvious downside is the need for frequent battery replacement, which can be impractical, costly and inconvenient. To combat this problem, most manufacturers aim to extend the battery life of their device to 10 years. Some are also even exploring alternative methods of power with energy harvesting solutions.
A common technique for achieving a 10-year battery life is to leverage the fact that IoT devices are inactive for the majority of the time and only need to support infrequent radio transmission of small data payloads. In most cases, sensor measurements are also infrequent. One example is an agricultural sensor node, which takes a handful of sensor measurements such as for temperature and humidity per day, followed by a daily transmission of data to the network. In terms of battery life, this is significant because most of the power draw from the battery occurs when transmitting or receiving data using either Bluetooth® Low Energy, Wi-Fi or Sub-Ghz, depending on the type of sensor used. When the IoT node is not transmitting or sensing, it will be sitting mostly in idle or low power mode with very little power draw from the battery. The percentage of time, known as Duty Cycle, of which the device is in active mode is easily less than 1 percent for most use cases, meaning that it is in low power mode for the remaining 99 percent. The infrequency of these power-hungry tasks can therefore significantly reduce power consumption and aid in extending battery life.
This means that the system will be operating in two distinct modes:
- Active mode: For data transmission and the high power draw sensing
- Low power mode: Where the system is in idle mode or low power sensing
In terms of current draw from the battery, active mode requires approximately tens of milliAmps (mA), while low power mode requires mere micro amps, a ratio of 1000 to 10,000 times.
Traditional high-efficiency solutions, like a switcher, do not necessarily lead to optimal power regulation for these types of applications. Instead, battery life can be optimized through the quiescent current of the low power mode simply because this is where the system operates most of the time.
With an astounding 50 nA of quiescent current, our Dual mode LDO, the NCP171, is designed for such low duty cycle IoT systems. The NCP171 has an innovative dual-mode architecture that delivers optimum performance for each of the two distinct modes of operation- active and low power. This means very low noise, fast regulations in active mode to ensure reliable data transmission and critical sensing, while offering Super Low Iq in low power mode for extended battery life. The two LDO modes can be selected by switching a dedicated ECO pin.
In active mode, the NCP171 provides up to 80 mA of load current with exceptional noise and dynamic performance required for reliable RF transmissions and very low noise performance for precision sensing. While in low power mode, the NCP171 draws extremely low quiescent current at just 50 nA for up to 5 mA of load leading to significantly increased battery life.
The NCP171 also offers a built-in voltage offset when switched to lower power mode to further reduce system power consumption by steps from 50 mV up to 200 mV.
Learn more about the LDO regulator and how it can achieve your low power battery design needs today.
