Power Supply For NB-IoT Modems Reference Design

The design helps smart meters run longer on battery, works in cold weather, and keeps power steady for NB-IoT communication.

TIDA-050010, a reference design from Texas Instruments (TI) offers a power supply solution for NB-IoT (Narrowband Internet of Things) applications in smart meters using LiSOCl₂ batteries. It features low standby current and high efficiency, extending battery life by over 50%. This solution is suitable for a range of smart metering applications, including gas meters, heat meters, and water meters.

Smart meters encompass a range of devices, including electricity, gas, heat, and water meters, many of which rely on Narrowband Internet of Things (NB-IoT) technology to transmit data efficiently. NB-IoT supports ultra-low power consumption, enabling battery lifespans of over 10 years across various applications. Modules like the ZTE ZM8300G typically require an input voltage between 3 V and 4.2 V (with 3.6 V as the nominal value) and can draw peak currents up to 300 mA during data transmission.

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Li-SOCl₂ batteries are commonly used in smart metering and tracking applications due to their high energy density, extended shelf life, and extremely low self-discharge rate—less than 1% per year at room temperature. These batteries typically provide a voltage range of 3 to 3.6 V and can deliver a maximum continuous output current of around 150 mA for an 8.5-Ah cell. However, since this current is insufficient for NB-IoT modules during peak load, a supercapacitor is connected in parallel to supply the necessary pulse current.

At lower ambient temperatures, the output voltage of Li-SOCl₂ batteries can fall below 3 V, causing NB-IoT modules to shut down even if a substantial portion of battery capacity (up to two-thirds at –20°C) remains. To address this issue, a boost converter such as the TPS610995 is used to maintain a steady 3.6 V output, ensuring reliable performance of the NB-IoT module regardless of temperature or battery discharge conditions.

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The design uses TPS610995, a small power chip that gives a fixed output of 3.6 V. This chip is very good at saving power—it uses only 1 microamp (µA) when not doing much and still works efficiently with very small loads. It can handle more power too, giving up to 320 milliamps (mA) when changing voltage from 2 V to 3.6 V, with up to 93% efficiency. The chip can also work when the input voltage is higher than the output voltage and still keep the output steady. When the chip is turned off, it fully disconnects from the battery so it doesn’t waste energy. 

It also includes LMC555, a low-power version of the popular 555 timer chip. It does the same job—creating time delays and pulses—but uses less power. In one-shot mode, it creates a single time delay, controlled by one resistor and one capacitor. In repeating (astable) mode, it makes a steady signal, with timing set by two resistors and one capacitor.

TI has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.