STMicroelectronics STM8S903F3M3

Overview

STM8S903F3M3 from STMicroelectronics is an 8-bit microcontroller featuring a 16 MHz STM8 core, 8 Kbytes Flash, 1 Kbyte RAM, and 640 bytes EEPROM. It integrates a 10-bit ADC with 7 multiplexed channels, UART, SPI, and I²C interfaces, and supports low-power modes including active-halt and halt. It is used in cost-sensitive industrial control panels requiring deterministic real-time response and firmware-upgradable sensor node logic.

For engineers reviewing the STM8S903F3M3 datasheet, STM8S903F3M3 pinout, STM8S903F3M3 application, or STM8S903F3M3 equivalent, key selection considerations include its 20-pin TSSOP/SO/UFQFPN package options, 2.95–5.5 V supply range, 16 MHz max CPU frequency, and integrated SWIM debug interface for in-circuit programming.

Technical Context

The STM8S903F3M3 implements a Harvard-architecture 8-bit core with 3-stage pipeline and extended instruction set, enabling single-cycle execution for most instructions. Its clock system includes four master sources: external crystal, external clock input, user-trimmable 16 MHz RC, and low-power 128 kHz RC - all monitored by a clock security system.

Interrupt handling uses a nested controller supporting 32 interrupts and up to 28 external vectors across 7 priority levels. Memory subsystem includes true data EEPROM (300 kcycle endurance) and Flash with 20-year data retention at 55 °C after 10 kcycles, managed via dedicated program/erase controllers.

Key Specifications

Pinout & Package

STM8S903F3M3 is available in TSSOP20 (4.4 mm body), SO20 (300 mil), and UFQFPN20 (3 × 3 mm, 0.5 mm pitch) packages. Pin functions are validated per DS6210 Rev 13 Sections 5.1–5.3 and Table 5.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S903F3M3, STM8S003F3P6 trades EEPROM and ADC features for lower cost in fixed-function roles, while EFM8BB10F8G offers enhanced analog performance at the expense of proven industrial EEPROM reliability and ST's ecosystem toolchain support.

Availability

STM8S903F3M3 is available at Aetrix Electronics and suitable for industrial motor control, smart sensor nodes, home appliance UI panels, and PLC I/O expansion modules requiring stable component supply and long-lifecycle availability.

Supply support for STM8S903F3M3 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 devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The STM8S series targets cost-optimized, robust 8-bit control applications in industrial automation and appliance control, emphasizing low-power operation, high I/O resilience, and seamless integration with ST's development ecosystem.

FAQ

What debug interface does STM8S903F3M3 support?

The STM8S903F3M3 uses the Single Wire Interface Module (SWIM) for in-circuit debugging and programming. It operates on PB4 (SWIM pin) and requires only one physical connection plus ground. SWIM supports full read/write memory access, breakpoint setting, and real-time variable inspection without halting peripheral operation.

Does STM8S903F3M3 support hardware UART auto-baud detection?

No, the STM8S903F3M3 UART does not implement hardware auto-baud detection. Baud rate is configured via the UARTDIV register using a programmable divisor derived from the APB clock. Synchronization relies on known clock source accuracy and external start-bit timing, requiring fixed or pre-negotiated baud rates in host communication.

Can the internal 16 MHz RC oscillator be calibrated for improved accuracy?

Yes, the internal 16 MHz RC oscillator (HSI) is user-trimmable via the CLK_HSITRIMR register. Trim values range from 0x00 to 0x1F, adjusting frequency in steps of approximately ±0.5% across the full range. Calibration is typically performed once during production using an external reference clock and stored in option bytes or application firmware.

What is the maximum operating temperature for STM8S903F3M3 in industrial grade?

The STM8S903F3M3 is qualified for industrial temperature range: –40 °C to +85 °C. This rating applies to all package variants (TSSOP20, SO20, UFQFPN20) and is verified per JEDEC JESD22-A104 and JESD22-A108 standards. Electrical characteristics in DS6210 Rev 13 Section 10.3 are specified across this full range.