STMicroelectronics STM8S903K3U6TR

Overview

STM8S903K3U6TR from STMicroelectronics is an 8-bit microcontroller featuring a 16 MHz STM8 core, 8 Kbytes Flash, 1 Kbyte RAM, and 640 bytes EEPROM, with integrated 10-bit ADC, UART, SPI, I²C, and two 16-bit timers. It operates from 2.95–5.5 V and targets cost-sensitive industrial control, sensor interface, and appliance motor management applications.

For engineers reviewing the STM8S903K3U6TR datasheet, STM8S903K3U6TR pinout, STM8S903K3U6TR application, or STM8S903K3U6TR equivalent, key selection criteria include its 32-pin LQFP/UFQFPN package, 28 GPIOs (21 high-sink), low-power active-halt mode (0.35 µA typ), SWIM debug interface, and dual watchdog timers for safety-critical firmware execution.

Technical Context

The STM8S903K3U6TR implements a Harvard-architecture 8-bit core with 3-stage pipeline and extended instruction set, enabling deterministic real-time response. Its clock system integrates four sources: 16 MHz user-trimmable RC, 128 kHz low-power RC, crystal oscillator, and external clock input - all monitored by a clock security system.

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

Key Specifications

Pinout & Package

LQFP32 (7 × 7 mm) and UFQFPN32 (5 × 5 mm) packages are supported; this part is supplied in UFQFPN32. Both packages provide identical pin mapping and electrical characteristics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S003F3P6 and STM8L051F3P6, the STM8S903K3U6TR uniquely balances mid-range I/O count (28 pins), full-featured timer suite (including TIM1 with dead-time), and robust industrial voltage range (2.95–5.5 V), making it optimal for wired industrial edge nodes requiring both processing headroom and peripheral flexibility.

Availability

STM8S903K3U6TR is available at Aetrix Electronics and suitable for industrial sensor nodes, smart appliance control, energy meter interfaces, and POS terminal peripherals requiring stable component supply and long-term manufacturability.

Supply support for STM8S903K3U6TR 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 management ICs, sensors, and automotive semiconductors.

The STM8S series was developed specifically for cost-sensitive, high-reliability industrial and consumer applications demanding robustness, low power, and ease of development - with SWIM debug and mature toolchain support.

FAQ

What debug interface does the STM8S903K3U6TR support?

The STM8S903K3U6TR uses the Single Wire Interface Module (SWIM), a proprietary ST protocol requiring only one dedicated pin (SWIM) plus VDD and VSS for full in-circuit programming and real-time debugging. It supports breakpoints, register inspection, and flash memory read/write without halting CPU execution during data transfers.

Does the STM8S903K3U6TR support hardware CRC calculation?

No, the STM8S903K3U6TR does not include a dedicated hardware CRC peripheral. CRC computation must be implemented in firmware using standard polynomial algorithms (e.g., CRC-8 or CRC-16), leveraging the MCU's efficient 8-bit ALU and loop instructions for acceptable throughput in communication protocols.

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

Yes, the internal 16 MHz RC oscillator includes a user-trimmable calibration register (CLK_HSICALR) allowing adjustment in ±1% steps across the full operating voltage and temperature range. Factory calibration value is stored in option bytes, and users may reprogram it based on system-level timing measurements.

What is the maximum allowed I²C bus speed and corresponding VDD requirement?

The STM8S903K3U6TR supports I²C up to 400 kbit/s in fast-mode, requiring VDD ≥ 3.0 V. At VDD = 2.95 V, maximum speed is limited to 100 kbit/s (standard-mode). Pull-up strength and bus capacitance must comply with I²C specification - typical design uses 4.7 kΩ pull-ups with ≤ 400 pF total capacitance.