STMicroelectronics STM8S903F3M3TR

Overview

STM8S903F3M3TR from STMicroelectronics is an 8-bit STM8 microcontroller with 8 Kbytes Flash, 1 Kbyte RAM, and 640 bytes EEPROM, featuring a 16 MHz core, 10-bit ADC, UART/SPI/I²C interfaces, and advanced timer peripherals. It targets cost-sensitive industrial control, sensor interface, and appliance motor management applications requiring low-power operation and robust I/O.

For engineers reviewing the STM8S903F3M3TR datasheet, STM8S903F3M3TR pinout, STM8S903F3M3TR application, or STM8S903F3M3TR equivalent, key selection criteria include its 20-pin TSSOP package, 2.95–5.5 V supply range, 300 kcycle EEPROM endurance, nested interrupt controller with 32 vectors, and SWIM single-wire debug interface.

Technical Context

The STM8S903F3 implements a Harvard-architecture 16 MHz STM8 core with 3-stage pipeline and extended instruction set, supporting up to 28 external interrupts across 7 vectors. Its clock system integrates four sources: low-power crystal oscillator, external clock input, user-trimmable 16 MHz RC, and 128 kHz low-power RC, all monitored by a clock security system.

Memory architecture includes 8 Kbytes of Flash (20-year data retention at 55 °C after 10 kcycles), 640 bytes of true data EEPROM (300 kcycle endurance), and 1 Kbyte RAM. Peripheral integration covers UART with SmartCard/IrDA/LIN support, SPI up to 8 Mbit/s, I²C up to 400 kbit/s, and three timers: TIM1 (16-bit advanced control), TIM5 (16-bit general purpose), and TIM6 (8-bit basic).

Key Specifications

Pinout & Package

STM8S903F3M3TR is packaged in a 20-pin TSSOP (4.4 mm body width) with 0.65 mm pitch, optimized for compact industrial PCB layouts and automated assembly. Thermal resistance θ_JA is 120 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with STM8S903F3M3TR, STM8S003F3P6 offers cost savings at the expense of memory scalability, while EFM8BB10F8G-A-QSOP24 trades supply flexibility and integrated EEPROM for enhanced analog features and different ecosystem dependencies.

Availability

STM8S903F3M3TR is available at Aetrix Electronics and suitable for industrial sensor nodes, smart appliance control, energy meter interfaces, and IoT edge gateway subsystems requiring stable component supply across multi-year production cycles.

Supply support for STM8S903F3M3TR 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, power ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The STM8S series delivers cost-optimized 8-bit MCUs targeting resource-constrained embedded applications where deterministic real-time response, low power, and high I/O robustness are critical - especially in white goods, building automation, and metering.

FAQ

What is the maximum operating frequency and corresponding supply voltage range?

The STM8S903F3M3TR achieves a maximum CPU frequency of 16 MHz across its full 2.95–5.5 V operating voltage range. At 3.3 V, it sustains 16 MHz operation with typical current consumption of 4.2 mA in run mode; at 5 V, it draws 5.8 mA under identical conditions. Frequency scaling is not required - the core runs at full speed down to the minimum supply voltage.

Does this MCU support in-system programming via SWIM, and what hardware is required?

Yes, STM8S903F3M3TR supports full in-system programming and debugging via the SWIM (Single-Wire Interface Module) using only the PD7 pin and ground. A standard ST-LINK/V2 or compatible debugger is required; no external bootloader or UART-based ISP is needed. SWIM enables read-out protection, option byte configuration, and real-time variable inspection during execution.

How many I/O pins support high-sink capability, and what is the rated current?

In the TSSOP20 package, 13 I/O pins (PA0–PA7, PD0–PD5) are specified as high-sink outputs, each capable of sinking up to 20 mA continuously. This eliminates the need for external driver transistors when interfacing with LEDs, relays, or small solenoids. The I/O structure is designed to withstand 5 V-tolerant inputs even when powered at 3.3 V.

Is there hardware support for LIN bus communication, and which peripheral handles it?

Yes, the UART1 peripheral includes dedicated LIN master mode support, enabling direct generation of LIN break fields, sync fields, and checksums without CPU intervention. This feature is enabled via the LINEN bit in the UART1_CR2 register and operates at standard LIN baud rates (e.g., 19.2 kbps) with automatic timing compensation for bus voltage variations.