STMicroelectronics STM8S903F3M6TR

Overview

STM8S903F3M6TR 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 targets cost-sensitive industrial control, sensor interface, and appliance motor management applications requiring low-power operation and robust I/O.

For engineers reviewing the STM8S903F3M6TR datasheet, STM8S903F3M6TR pinout, STM8S903F3M6TR application, or STM8S903F3M6TR equivalent, key selection criteria include its 20-pin TSSOP package, 2.95–5.5 V supply range, nested interrupt controller supporting 32 interrupts, and dual watchdog timers for safety-critical firmware execution.

Technical Context

The STM8S903F3M6TR implements a Harvard-architecture STM8 core with 3-stage pipeline and extended instruction set, enabling deterministic real-time response. Its clock system integrates four independent sources: external crystal, external clock input, user-trimmable 16 MHz RC, and low-power 128 kHz RC - all monitored by a dedicated clock security system.

Memory architecture includes separate program (Flash) and data (EEPROM + RAM) spaces, with true data EEPROM endurance rated at 300 kcycles and 20-year data retention at 55 °C. Peripheral clock gating allows selective power-down of UART, SPI, I²C, and timers to minimize active-halt mode current consumption.

Key Specifications

Pinout & Package

STM8S903F3M6TR is packaged in a 20-pin TSSOP (4.4 mm body width), with 18 general-purpose I/O pins, including 16 high-sink outputs capable of 20 mA sink per pin. The package supports standard reflow soldering and fits compact PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S003F3P6, STM8S903F3M6TR provides double Flash and 5× more EEPROM for firmware flexibility and data logging; versus EFM8BB10F8G-A-QSOP24, it delivers native EEPROM, higher I/O sink strength, and lower standby power - reducing component count and power management complexity.

Availability

STM8S903F3M6TR 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 across multi-year production cycles.

Supply support for STM8S903F3M6TR 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 was engineered specifically for cost-sensitive, reliability-critical embedded control applications - emphasizing low-power operation, robust I/O, and integrated peripherals to reduce external component count in white goods, building automation, and metering systems.

FAQ

What is the maximum operating frequency of the STM8S903F3M6TR?

The STM8S903F3M6TR operates at up to 16 MHz across its full 2.95–5.5 V supply range. This frequency is achievable using the internal 16 MHz RC oscillator (trimmable to ±1%), external crystal (up to 24 MHz), or external clock source. No external PLL is required, and timing specifications in the datasheet (DS6210 Rev 13, Section 10.3.4) guarantee setup/hold margins at this speed under all valid VDD and temperature conditions.

Does the STM8S903F3M6TR support in-system programming via SWIM?

Yes, the STM8S903F3M6TR supports full in-system programming and debugging through its single-wire interface module (SWIM) using the SWIM pin. This requires only one signal line plus ground, eliminating the need for multi-pin debug headers. ST-LINK/V2 and compatible programmers provide full read/write/erase access to Flash and EEPROM, and support breakpoint-based debugging without halting peripheral operation.

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

Up to 21 I/O pins on the STM8S903F3M6TR support high-sink output capability, each rated for 20 mA DC sink current at VDD = 5 V (Section 10.3.6, Table 43). These pins can directly drive LEDs, relays, or small solenoids without external drivers. Total simultaneous sink current is limited to 80 mA across all ports, and thermal derating applies above 70 °C ambient.

Is there hardware support for I²C clock stretching or arbitration?

Yes, the integrated I²C interface supports full multimaster arbitration and clock stretching. The hardware automatically handles SCL low extension during slave processing, and detects bus collisions during address/data transmission. Arbitration is resolved bit-by-bit using wired-AND logic on SDA, with the master retaining control whose data bit is '1' when the other transmits '0'. This complies with I²C specification v2.1 and is verified in electrical characteristics (Table 46, Section 10.3.9).