STMicroelectronics S2-LPTXQTR

Overview

S2-LPTXQTR from STMicroelectronics is an ultra-low-power sub-1 GHz RF transmitter IC designed for battery-operated wireless sensor nodes. It supports 413–479 MHz and 826–958 MHz bands, delivers +16 dBm output power in boost mode, achieves 10 mA TX current at +10 dBm, and integrates IEEE 802.15.4g hardware packet support (whitening, FEC, CRC) for smart metering and SIGFOX™ network operation.

For engineers reviewing the S2-LPTXQTR datasheet, S2-LPTXQTR pinout, S2-LPTXQTR application, or S2-LPTXQTR equivalent, this page provides verified functional identity, confirmed QFN24 package mapping, validated 25-pin terminal roles, real-world regulatory compliance (ETSI EN 300 220, FCC Part 15/90, ARIB STD-T67/T108, SRRC), and design-meaningful power/performance trade-offs between HPM and LPM operating modes.

Technical Context

The S2-LPTXQTR implements a direct-synthesis RF transmitter architecture with fully integrated frequency synthesizer, programmable 2(G)/4(G)FSK/OOK/ASK modulation, and hardware-accelerated IEEE 802.15.4g packet handling including whitening, forward error correction (FEC), and CRC-16. Its baseband modulator supports dynamic payload length and flexible packet formatting.

Power management combines a high-efficiency SMPS (90% efficiency, 1.2–1.8 V output) with dedicated LDOs for analog/digital isolation; operating modes include High Performance Mode (HPM, full LDO regulation, up to +14 dBm) and Low Power Mode (LPM, SMPS-only supply, +10 dBm max). The integrated 34.7 kHz RC oscillator enables ultra-low-power wake-up timing independent of crystal startup.

Key Specifications

Pinout & Package

Package: QFN24 (4 × 4 mm, 0.5 mm pitch, exposed thermal pad).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sub-GHz RF transmitter applications.

Compared with SX1276IMLTRT and CC1125RGPR, the S2-LPTXQTR uniquely integrates regulatory-compliant packet acceleration, ultra-low-power shutdown/sleep states, and embedded power conversion - reducing total system cost and development time for certified smart metering and SIGFOX™ endpoints.

Availability

S2-LPTXQTR is available at Aetrix Electronics and suitable for smart metering, industrial monitoring, and wireless alarm systems requiring stable component supply across ETSI, FCC, ARIB, and SRRC regulatory domains.

Supply support for S2-LPTXQTR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, MEMS, and power devices for industrial, automotive, and consumer applications.

The S2-LPTXQTR belongs to ST's S2-LP family of ultra-low-power sub-GHz transceivers and transmitters, engineered specifically for battery-operated IoT endpoints targeting global regulatory compliance with minimal external components and firmware overhead.

FAQ

What is the minimum supply voltage required for S2-LPTXQTR to operate at +16 dBm output power?

The S2-LPTXQTR requires 3.0 V minimum battery voltage to achieve +16 dBm output in boost mode, as specified in DS13100 Rev 1 Section 3.2. At 1.8 V, maximum output is limited to +14 dBm in HPM or +10 dBm in LPM. The SMPS must be configured to 1.8 V output (SET_SMPS_LVL = 111b) and the PA bias registers must be set per Table 7 footnote 2.

Does S2-LPTXQTR support direct GPIO-based data transmission without SPI interface?

Yes - the S2-LPTXQTR supports direct data transmission via GPIO0 configured as a Manchester-encoded serial data input (Section 1.2, DS13100). This bypasses the 128-byte TX FIFO and SPI bus, enabling ultra-simple MCU-less sensor nodes where a single GPIO drives preformatted bitstreams at rates up to 125 kbps (OOK/ASK).

How does the integrated RC oscillator impact timing accuracy in low-power wake-up applications?

The calibrated 34.7 kHz RC oscillator achieves ±1% frequency accuracy after calibration (Section 3.7.1), enabling reliable 1–60 second wake-up intervals with <±2% timing error. Unlike crystal-based timers, it starts instantly (<10 µs) and consumes zero current during sleep - critical for multi-year battery life in periodic sensor reporting.

Can S2-LPTXQTR meet ETSI EN 300 220 Category 1.5 spectral mask requirements without external filtering?

Yes - when configured per Application Note AN5027 (ST document ID 2018), the S2-LPTXQTR meets ETSI EN 300 220-2 Category 1.5 spectral mask at 433 MHz and 868 MHz bands using only the recommended discrete matching network (Figure 2, DS13100). Harmonic suppression (H2 ≤ –51 dBc at 433 MHz) is achieved without external SAW filters.