Item specifics
Description
The STM8S903K3T6C is a mainstream application specific line 8-bit MCU from STMicroelectronics, classified as a low-density device in the STM8S family (RM0016). Featuring a 16 MHz advanced STM8 core with Harvard architecture and 3-stage pipeline, it integrates 8 KB Flash, 1 KB RAM, and 640-byte true data EEPROM (endurance: 300k write/erase cycles — 3x the typical industry standard). On-chip peripherals include a 10-bit ADC (7 multiplexed channels + 1 internal channel, scan mode, analog watchdog), 16-bit advanced control timer (4 CAPCOM channels, 3 complementary outputs with dead-time insertion), 16-bit general-purpose timer (3 channels IC/OC/PWM), 8-bit basic timer, auto wakeup timer, window and independent watchdog timers, and UART (with clock output, SmartCard, IrDA, LIN master mode), SPI (up to 8 Mbit/s), and I2C (up to 400 Kbit/s) interfaces. Packaged in LQFP-32 (7×7×1.4 mm) with 28 I/Os (including 21 high-sink outputs) and highly robust I/O design immune against current injection, it operates from 2.95 V to 5.5 V over -40 °C to 85 °C. Ideal for industrial control, LED lighting, motor control, consumer electronics, and cost-sensitive applications requiring high performance and reliability.
Advanced Core: 16 MHz STM8 core, Harvard architecture, 3-stage pipeline, extended instruction set, up to 28 external interrupts on 7 vectors, 32 nested interrupts Memory: 8 KB Flash (20-year data retention at 55 °C after 10k cycles), 1 KB RAM, 640-byte true data EEPROM (300k write/erase cycles) 10-bit ADC: 7 multiplexed channels + 1 internal channel, ±1 LSB accuracy, scan mode, analog watchdog, internal reference voltage measurement Advanced Control Timer: 16-bit, 4 CAPCOM channels, 3 complementary outputs, dead-time insertion and flexible synchronization General-Purpose Timer: 16-bit, 3 CAPCOM channels (IC/OC/PWM); 8-bit basic timer with 8-bit prescaler Auto Wakeup Timer: Wakeup from Active-halt mode Dual Watchdogs: Window watchdog + Independent watchdog with separate clock source Communication Interfaces: UART with clock output, SmartCard, IrDA, LIN master mode; SPI up to 8 Mbit/s; I2C up to 400 Kbit/s Clock System: 4 master clock sources (external clock, crystal oscillator, user-trimmable 16 MHz RC, low-power 128 kHz RC), clock security system with monitor Low-Power Modes: Wait, Active-halt, Halt; individually switchable peripheral clocks High Reliability: Low-consumption POR/PDR, highly robust I/O design immune against current injection, 96-bit unique ID per device LQFP-32 Package: 7×7×1.4 mm, 28 I/Os including 21 high-sink outputs Wide Operating Range: 2.95 V to 5.5 V, -40 °C to 85 °C Development Support: Embedded SWIM single-wire interface for fast on-chip programming and non-intrusive debugging
Industrial Control: PLCs, sensor transmitters, RS-485 nodes, small actuators LED Lighting: Dimming control, RGB strips, switching power supplies; direct PWM drive Motor Control: Fans, pumps, small motors; advanced timer with complementary PWM and dead-time Battery Management: Protection boards, fuel gauges, charge management; low-power modes reduce standby Home Appliances: Induction/microwave oven panels, small appliance main controllers Sensor Modules: Temperature/humidity/gas sensing; 10-bit ADC + I2C/UART flexible networking Consumer Electronics: Remote controls, electric toothbrushes, electronic toys; high-value 32-pin solution Automotive Electronics: Vehicle light control, window anti-pinch, automotive sensor nodes (non-safety-critical)
Cost-Effective Performance Combo: 8 KB Flash + 1 KB RAM + 640 B true EEPROM (300k cycles) + 10-bit ADC + advanced control timer (complementary PWM/dead-time) + UART/SPI/I2C in LQFP-32 package 300k High-Endurance EEPROM: 640-byte true data EEPROM with 300k write/erase cycles (3x standard endurance), reliably storing calibration parameters Advanced Timer for Motor Control: 4 CAPCOM channels, 3 complementary outputs with dead-time insertion, driving half-bridge circuits and motor control Rich I/O Resources: 28 I/Os with 21 high-sink outputs, delivering high pin utilization in a 32-pin package Robust & Reliable: 4 clock sources + clock security system, low-consumption POR/PDR, independent watchdog with separate clock source Mature Ecosystem: STM8 classic architecture, rich documentation, low-cost SWIM debug Pin-Compatible with S103 Series: Direct drop-in replacement for STM8S103K3T6C with full software compatibility — no code changes required
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FAQ:
What is the STM8S903K3T6C and what are its key specifications?
The STM8S903K3T6C is an 8‑bit microcontroller from STMicroelectronics, built around the high‑performance STM8 core running at up to 16 MHz. It offers 8 KB of Flash program memory, 1 KB of SRAM, and 640 bytes of true data EEPROM for non‑volatile parameter storage. On‑chip peripherals include a 10‑bit ADC, an advanced 16‑bit timer (TIM1) with complementary outputs, general‑purpose timers (TIM2 and TIM4), and communication interfaces — UART, SPI, and I2C. Housed in an LQFP‑32 package, it provides up to 28 I/O pins and operates over ‑40 °C to +85 °C. This MCU combines the fast STM8 core with a rich set of peripherals, making it a solid choice for industrial, consumer, and automotive sensor applications where cost, performance, and package size must be carefully balanced.
What are the package dimensions and I/O count of the STM8S903K3T6C?
The device uses an LQFP‑32 package measuring 7 mm × 7 mm with a lead pitch of 0.8 mm. It provides up to 28 general‑purpose I/O pins, a generous number for a 32‑pin package. The 0.8 mm pitch makes the chip comfortable to hand‑solder and prototype with, while the exposed leads allow easy visual inspection. This package is a popular upgrade path from smaller 20‑pin devices when more I/O is needed but PCB space is still limited.
How does the STM8S903K3T6C differ from the STM8S003K3T6C? Is it worth the upgrade?
Both are STM8 core MCUs running at 16 MHz in an LQFP‑32 package with 28 I/O pins. They share the same Flash and SRAM sizes — 8 KB Flash and 1 KB SRAM. The key difference is the EEPROM: the S903 offers 640 bytes of true EEPROM, whereas the S003 only emulates EEPROM in Flash (with limited write endurance). The S903 also typically includes a more robust set of analog features and slightly better parametric specifications (e.g., tighter internal oscillator accuracy over temperature). If your application needs to frequently store calibration data or user settings, the genuine EEPROM of the S903 is a major advantage. For simple applications without such requirements, the S003 is a perfectly cost‑optimized alternative.
How does the STM8S903K3T6C compare with the STM8S105K4T6C? Which one should I choose for more memory?
The STM8S105K4T6C is a step‑up model in the same LQFP‑32 package, offering 16 KB Flash, 2 KB SRAM, and 1 KB EEPROM. Both share the same core, I/O count, and most peripherals. The S903K3 is very capable with 8 KB Flash and 1 KB RAM for compact, highly optimized applications. If your firmware is approaching the 8 KB limit, or you need larger data buffers, the S105K4 gives you twice the memory and more EEPROM in the same footprint. The S903K3 remains an excellent choice when the application fits comfortably within 8 KB and you want to minimize cost while keeping the real EEPROM advantage.
What timers does the STM8S903K3T6C have, and can it generate complementary PWM signals?
It includes an advanced 16‑bit timer (TIM1) with 3 complementary PWM pairs, dead‑time insertion, and a break input. This makes the chip perfectly capable of directly driving a three‑phase brushless DC motor or a three‑phase inverter without external gate‑driver logic. There are also general‑purpose timers — TIM2 (16‑bit) and TIM4 (8‑bit) — which can be used for input capture, regular PWM generation, or basic time‑base functions. This timer set gives the S903 a strong advantage in motor control and lighting applications that require three‑phase waveforms.
What are the ADC specifications of the STM8S903K3T6C? How many analog input channels can I use?
The integrated 10‑bit successive‑approximation ADC provides a good balance of speed and resolution for most embedded sensing tasks. In the LQFP‑32 package, up to 7 external analog input channels are available (shared with digital pins through the AINx multiplexer). The ADC can also measure an internal reference voltage. There is no on‑chip DAC; analog outputs can be emulated by filtering a PWM signal if a low‑cost solution is required.
Can the STM8S903K3T6C be powered by 5 V directly? What is its supply voltage range?
Yes — this is one of the major advantages of the STM8S family. The device operates from 2.95 V to 5.5 V, so it can be powered directly from a 5 V rail without any regulator. All I/O pins are 5 V tolerant and can interface directly with 5 V logic, TTL, or CMOS devices. The on‑chip regulator also allows the MCU to run reliably from a wide range of supplies, including batteries or loosely regulated adapters, making it very forgiving in noisy industrial environments.
How low is the power consumption of the STM8S903K3T6C, and does it have any low‑power modes?
The STM8S903K3T6C is primarily designed for active operation and does not focus heavily on ultra‑low‑power sleep modes. It supports Wait and Active‑halt modes, which can reduce current consumption significantly compared to Run mode. In Active‑halt mode with the main clock stopped, the consumption can drop to a few tens of microamps, though the exact value depends on the voltage and temperature. It also includes a low‑power watchdog (IWDG) that remains active even in halt mode. For battery‑powered applications that need longer sleep periods, the STM8L series (with dedicated low‑power modes) is a more suitable choice.
How do I program and debug the STM8S903K3T6C? What development tools are needed?
Programming and debugging are done via the SWIM (Single Wire Interface Module) interface, which needs only one data pin, plus reset and ground. A low‑cost ST‑LINK/V2 programmer (with SWIM support) is all the hardware you need. For software, you can use STVD (ST Visual Develop) together with the Cosmic C compiler, or the free open‑source SDCC compiler. ST provides a full set of standard peripheral libraries for the STM8S family, which greatly simplifies bringing up peripherals. Many example projects for motor control, sensor acquisition, and communication are available to help you get started quickly.
What are the most typical applications for the STM8S903K3T6C?
Thanks to its robust 5 V operation, three‑phase motor‑control timer, and true EEPROM, the S903K3 is widely used in cost‑sensitive yet demanding embedded systems. Typical applications include three‑phase brushless DC motor drivers (small fans, pumps, power tools), smart sensors with parameter storage, home appliances (washing machines, dishwashers), industrial timers and controllers, and automotive body electronics. It is especially popular when a small 32‑pin footprint, reliable EEPROM, and the ability to run directly from a 5 V supply are all important design requirements.