STMicroelectronics STM8S903K3U3TR

Overview

STM8S903K3U3TR 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, I²C, and two 16-bit timers - used in industrial sensor nodes requiring low-power operation and mixed-signal control.

For engineers reviewing the STM8S903K3U3TR datasheet, STM8S903K3U3TR pinout, STM8S903K3U3TR application, or STM8S903K3U3TR equivalent, key selection criteria include its 32-pin LQFP/UFQFPN package, 2.95–5.5 V supply range, nested interrupt controller with 32 vectors, and support for SmartCard/IrDA/LIN via UART.

Technical Context

The device implements a Harvard-architecture STM8 core with 3-stage pipeline and extended instruction set, enabling deterministic real-time execution. Its clock system includes four independent sources: external crystal (up to 16 MHz), external clock input, user-trimmable 16 MHz RC, and low-power 128 kHz RC - all managed by a clock security system with monitor.

Power management supports three low-power modes (wait, active-halt, halt) with individual peripheral clock gating. The nested interrupt controller handles up to 28 external interrupts across 7 vectors, while the advanced control timer (TIM1) provides dead-time insertion and complementary outputs for motor control.

Key Specifications

Pinout & Package

LQFP32 (7 × 7 mm) and UFQFPN32 (5 × 5 mm) packages are supported; both use 32-pin layouts with identical signal mapping per datasheet Section 5.4–5.5. Pin functions include dedicated SWIM debug interface, NRST reset, VCAP decoupling capacitor terminal, and multiple alternate-function remappable I/Os.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8L151K4T6 and STM32F030F4P6, the STM8S903K3U3TR delivers optimal balance of EEPROM persistence, motor-control peripherals, and cost-sensitive 8-bit performance - making it ideal for established industrial and automotive body electronics where legacy compatibility and deterministic timing are critical.

Availability

STM8S903K3U3TR is available at Aetrix Electronics and suitable for industrial sensor nodes, smart home actuators, medical diagnostic tools, and automotive body control modules requiring stable component supply over extended production lifecycles.

Supply support for STM8S903K3U3TR 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 targets cost-sensitive, high-reliability embedded control applications - emphasizing robustness, integrated peripherals, and long-term availability for industrial automation and automotive subsystems.

FAQ

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

The STM8S903K3U3TR operates at up to 16 MHz across its full 2.95–5.5 V supply range. At 3.3 V, it sustains 16 MHz reliably per electrical characteristics Table 21; at 2.95 V, maximum frequency is reduced to 12 MHz per Figure 10. No external PLL is used - CPU clock derives directly from selected oscillator source.

Does this MCU support in-circuit debugging and programming?

Yes, it uses the Single-Wire Interface Module (SWIM) for non-intrusive debugging and programming via the SWIM pin (Pin 27). ST-LINK/V2 and compatible debuggers support full flash read/write, breakpoint setting, and real-time register inspection without requiring additional pins or bootloaders.

How is the internal EEPROM endurance verified and what usage model does it support?

The 640-byte data EEPROM is guaranteed for 300,000 write/erase cycles per byte, with data retention exceeding 20 years at 55 °C after 10,000 cycles. It supports byte-wise erase and write operations, enabling direct storage of calibration coefficients, device configuration, or usage counters without wear-leveling software.

Can the UART interface support LIN 2.2 physical layer communication?

Yes, the UART1 peripheral includes dedicated LIN master mode with automatic sync field generation, checksum calculation, and baud rate flexibility (1–20 kbit/s). It meets ISO 17987-4 requirements for LIN slave node response timing and supports wakeup via dominant bus level detection on RX pin.