The S2-LP from STMicroelectronics is a Sub-1 GHz Transceiver that operates in the license-free ISM bands and SRD frequency bands of 433, 512, 868, and 920 MHz. It can also be programmed to support additional frequencies from 413-479 MHz, 452-527 MHz, 826-958 MHz, and 904-1055 MHz. This transceiver supports 2(G)FSK, 4(G)FSK, OOK, and ASK modulation schemes and can be used in systems with channel spacing down to 1 kHz. It has an RF link budget of more than 140 dB for long communication ranges with an air data rate of up to 500 Kbps. The transceiver is designed to enable operations in the Sigfox and MONARCH networks and meets the regulatory requirements applicable in territories worldwide, including Europe, Japan, China, and the USA.
The S2-LP consists of an LNA, LDO regulator, temperature sensor, Tx/Rx FIFO for data storage, registers, mixers, gain block, ?? ADCs, frequency synthesizers, 52 MHz crystal oscillator (XO), modulator/demodulator, serial interfaces, data link layer, and radio and power control. It provides an embedded programmable automatic acknowledgment, automatic packet retransmission, CSMA/CA engine, low-duty cycle, Rx sniff mode, and timeout protocol to reduce overall system power consumption and increase communication reliability. This transceiver offers complete antenna switching algorithms to support antenna diversity for better signal reception. It integrates a configurable baseband modem with a proprietary fully programmable packet format, thereby supporting IEEE 802.15.4g and wireless M-bus applications.
This transceiver allows transmitted/received data bytes to be buffered in two 128-byte-FIFOs (Tx FIFO and Rx FIFO) and allows them to be remotely accessed via a 4-pin SPI serial interface for host processing. It uses either the internal oscillator to digitally configure to operate with different crystals or an external clock signal to feed the input for proper operation. The transceiver also has an integrated low-power RC oscillator that generates a 34.7 kHz clock signal for the slowest timeouts. It incorporates four general-purpose I/O interfaces to offer multiple and parallel communication with the MCU.
The S2-LP requires a DC supply from 1.8 V to 3.6 V and consumes 7 mA of current in the Tx mode and 10 mA of current in the Rx mode. It is available in a surface-mount package that measures 4 x 4 mm and is ideal for wireless alarm systems, industrial monitoring, and control, sensors-to-cloud, home energy management systems, smart home, building automation, and smart metering applications.
