Supplement: Power
Fig. 2: the nPZero with reconfigurable logic can be programmed to fit different application requirements
Broad scope for system power savings
This architecture might have little significance for designers of battery- powered IoT systems if the nPZero itself were an ordinary semiconductor device. The diagram in Figure 2 makes it look familiar: the nPZero contains a reconfigurable logic block, which enables operational parameters such as sensor wake-up times and threshold values to be configured by the system designer, giving it a large amount of flexibility without the need for a dedicated MCU. But a distinctive aspect of the nPZero is the proprietary sub-threshold semiconductor technology used to implement the analogue and digital features of the device. This technology, developed by Nanopower Semiconductor, produces extraordinary savings in operating
power consumption: when operating as the system controller, managing up to four sensors, the nPZero typically reduces the idle current of the system to 100nA or less. In IoT designs demonstrated by Nanopower, system power savings of up to 90 per cent are achieved. An evaluation has been performed based on the nPZero DevKit, using the included temperature sensor and accelerometer, and a Nordic nRF52840-based host. This system might typically be used in applications such as monitoring the condition of goods in transit, or for cold-chain data logging. When the demo system operates without the nPZero – that is, with the nRF52840 SoC controlling the sensors’ operation directly via I2C interfaces and with the nPZero disabled – average current over one hour’s typical operation is 395.4µA. The system is set to transmit status updates
every five minutes, as well as to trigger actions when the temperature moves outside a preset operating window. After enabling the nPZero to control the system via I2C, allowing the nRF52840 to be switched off between transmissions and the sensors to be duty-cycled, average current falls to 49.6µA – a reduction of 87 per cent, while providing exactly the same functionality and performance, including the transmission of status updates every five minutes.
Simple system evaluation and
System designers will find it easy to configure the nPZero to operate as a system controller, because Nanopower provides a zero-code nPZero Configurator graphical tool for configuring sensors in the system, applying polling schedules, and setting the parameters for triggering events (see Figure 3). The nPZero Configurator tool automatically generates the firmware code needed for the host MCU to configure the nPZero IC, which appears to the MCU as a standard peripheral. The code can be inspected and manually edited in the tool if needed.
Additionally, the tool can analyse the state of power switches and serial interfaces
Fig. 4: The modular Dev Kit allows engineers to evaluate the nPZero with their choice of MCU and sensors
in a running system, allowing the user to evaluate the efficiency of a given implementation, and to tune the configuration of the nPZero device to their requirements.
Evaluation is enabled by the modular design of the nPZero Development Kit: it is based on a motherboard featuring the nPZero IC, into which PMOD sensor boards and SoC daughterboards with an Arduino Uno-compatible interface can be plugged (see Figure 4). This development platform enables wireless IoT product designers to quickly test their application in the same way as the cold-chain data logging system described above, using their choice of wireless SoC and sensor(s), and to compare system power consumption with and without the nPZero IC.
Thanks to the sub-threshold technology employed in the nPZero, and its ability to duty-cycle sensors via I2C or SPI, system designers can expect dramatic power savings which will enable them to greatly extend battery run-time between replacements, or implement an improved design with a smaller, lighter, and cheaper battery.
Fig. 3: the nPZero Configurator provides a GUI-based interface for choosing sensor thresholds and other operational parameters
www.cieonline.co.uk https://nanopowersemi.com/ Components in Electronics July/August 2025 35
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