The **AX-SFUS-API** is a high-performance, ultra-low power SoC (System on Chip) solution specifically designed for **Sigfox** network connectivity in the RC1 region (North America). It is part of the ON Semiconductor (onsemi) AX series. --- ## 1. Core Technical Specifications The device integrates a radio transmitter/receiver with an ARM Cortex-M0+ microcontroller, allowing it to function as a standalone communication node. | Feature | Specification | | :--- | :--- | | **RF Range** | 902 MHz (RC1 Region - North America) | | **Modulation** | DBPSK (Uplink), GFSK (Downlink) | | **MCU Core** | ARM® 32-bit Cortex®-M0+ | | **Supply Voltage** | 1.8V to 3.6V | | **TX Current** | ~45 mA @ +24 dBm | | **RX Current** | ~15 mA | | **Sleep Current** | ~0.5 μA (Deep Sleep) | --- ## 2. Key Electronic Components & Subsystems ### A. Radio Transceiver The RF frontend is highly integrated, supporting Sigfox's Ultra Narrow Band (UNB) technology. - **Power Amplifier (PA):** Capable of delivering up to +24 dBm, ensuring long-range connectivity even in challenging environments. - **Synthesizer:** High-precision frequency control to meet the strict 100Hz/600Hz bandwidth requirements of Sigfox. ### B. Microcontroller Unit (MCU) The "API" suffix indicates that the chip's internal ARM Cortex-M0+ is available for user applications. - **Flash Memory:** Typically 128 KB for user code and Sigfox stack. - **RAM:** 16 KB for data processing. - **Peripherals:** Includes UART, SPI, I2C, ADC, and GPIOs to interface with sensors (temperature, humidity, motion). ### C. Power Management Designed for battery-operated devices (IoT), it features: - **Voltage Regulators:** Internal LDOs to stabilize internal logic. - **Low Power Modes:** Multiple sleep states to extend battery life for up to 10 years on a single AA battery. --- ## 3. Circuit Integration Requirements To build a functional device around the AX-SFUS-API, the following external components are typically required: 1. **TCXO (Temperature Compensated Crystal Oscillator):** Critical for frequency stability in narrow-band communication. 2. **Antenna Matching Network:** A passive LC circuit (Inductors/Capacitors) to match the 50-ohm impedance for the antenna. 3. **Decoupling Capacitors:** Placed near VDD pins to filter high-frequency noise. --- ## 4. Programming and Interface The device is programmed using the **AX-Radio-Lab** software suite or standard ARM development tools. Communications with external sensors or host processors usually occur via: - **AT Command Set:** If used as a modem. - **Direct API Calls:** If the user application is running directly on the internal M0+ core.