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STMicroelectronics STM8S903F3M6TR — Microcontrollers & Processors (MCU / MPU / DSP)

ST STM8S903F3M6TR 8-bit MCU, 16 MHz, 8 KB Flash, 20-SOIC

MPNSTM8S903F3M6TR
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STMicroelectronics STM8S903F3M6TR, STM8S series 8-bit MCU, 16 MHz, 8 KB Flash, 1K x 8 RAM, 640 x 8 EEPROM, 20-SOIC (7.50mm width), -40°C to 85°C, 2.95 V to 5.5 V supply.

$2.3700Ref. price · indicative, final on quote
STMicroelectronics STM8S903F3M6TR datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

STM8S903F3M6TR specifications
ParameterValue
SeriesSTM8S
MountingSurface Mount
Oscillator typeInternal
Program memory typeFLASH
Voltage - supply (Vcc (Vdd))2.95V ~ 5.5V
Operating temperature-40°C~85°C(TA)
Speed16MHz
PackageTape & Reel (TR); Cut Tape (CT)
RAM size1K x 8
Core size8-Bit
EEPROM size640 x 8
PeripheralsBrown-out Detect/Reset, POR, PWM, WDT
ConnectivityI²C, IrDA, LINbus, SPI, UART/USART
Number of i (O)16
Core processorSTM8
Case20-SOIC (0.295\", 7.50mm Width)
Data convertersA/D 5x10b
Program memory size8KB (8K x 8)

Product details

16 MHz 8-bit MCU with integrated EEPROM and flexible peripherals

The STMicroelectronics STM8S903F3M6TR is an 8-bit microcontroller from the STM8S family, built around the STM8 core running at 16 MHz. On-chip peripherals include a 5-channel 10-bit ADC, PWM timers, a watchdog timer (WDT), and brown-out detect/reset (BOR/POR).

Memory sizing — 8 KB Flash, 1 KB RAM, 640 B EEPROM

With 8 KB of Flash and 1 KB of RAM, this part targets firmware footprints typical of simple control loops, state machines, and communication protocol stacks (e.g., LIN slave, I²C sensor hub). The 640-byte EEPROM is rated for 100k erase/write cycles per byte (per STM8S datasheet typical), allowing field-updatable parameters without wearing out the Flash. If the application needs more than 1 KB of runtime data memory, consider moving to a higher-RAM STM8S variant or adding external SRAM.

20-SOIC package — footprint and assembly notes

The 20-SO supplier package code (20-SO) indicates the standard wide SOIC footprint. No exposed thermal pad — junction-to-ambient thermal resistance is managed through the package leads and PCB copper pour.

Frequently asked questions

What is the difference between STM8S903F3 and STM8S903K3?

The key difference is package and pin count. The STM8S903F3M6TR comes in a 20-pin SOIC package (20-SOIC), while the STM8S903K3 variant typically uses a 32-pin LQFP or QFN package. The 32-pin version offers more I/O pins and may include additional peripheral pins (e.g., extra ADC channels or a second UART), but the core, Flash, RAM, and EEPROM sizes are identical. The 20-pin part is the compact option for space-constrained designs.

What is the substitute for STM8S903F3M6TR?

No official pin-compatible substitute is listed in the manufacturer's cross-reference. Within the STM8S family, the STM8S903K3 (32-pin) shares the same core and memory but has a different footprint. For a drop-in replacement, evaluate the STM8S003F3 (20-pin, lower Flash/RAM) or STM8S005C6 (48-pin, larger memory) — but each requires a firmware port and pinout check. No second-source vendor offers a direct pin-compatible alternate for this exact order code.