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STMicroelectronics STM8S903K3B6
- Part No.:
- STM8S903K3B6
- Manufacturer:
- STMicroelectronics
- Category:
- Microcontrollers
- Package:
- 32-SDIP (0.400", 10.16mm)
- Datasheet:
-
STM8S903K3B6.pdf
- Description:
- IC MCU 8BIT 8KB FLASH 32SDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,767
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Product details
Overview
STM8S903K3B6 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 STM8S903K3B6 datasheet, STM8S903K3B6 pinout, STM8S903K3B6 application, or STM8S903K3B6 equivalent, key selection criteria include its 32-pin LQFP/UFQFPN package compatibility, 2.95–5.5 V supply range, nested interrupt controller supporting 32 interrupts, and SWIM single-wire debug interface for space-constrained embedded firmware development.
Technical Context
The STM8S903K3B6 implements a Harvard-architecture STM8 core with 3-stage pipeline and extended instruction set, enabling deterministic real-time execution. Its clock system includes four master sources: external crystal, external clock input, user-trimmable 16 MHz RC, and low-power 128 kHz RC - all managed via dedicated clock security and gating registers.
Analog and timing subsystems are tightly coupled: the 10-bit ADC supports scan mode and analog watchdog, while TIM1 (advanced control timer) provides 4 CAPCOM channels, 3 complementary outputs, and dead-time insertion - essential for motor control and power conversion where precise PWM synchronization is required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Core | 16 MHz STM8 8-bit CPU with Harvard architecture and 3-stage pipeline - enables deterministic interrupt latency and efficient code density. |
| Memory | 8 Kbytes Flash (20-year data retention at 55 °C), 640 bytes EEPROM (300 kcycle endurance), 1 Kbyte RAM - supports field firmware updates and parameter storage without external memory. |
| ADC | 10-bit ±1 LSB ADC with up to 7 external channels + 1 internal reference channel - sufficient for precision temperature, voltage, and current sensing in closed-loop systems. |
| Timers | TIM1 (16-bit advanced control), TIM5 (16-bit general purpose), TIM6 (8-bit basic), AWU timer, and dual watchdogs - enables multi-rate timing, motor commutation, and fail-safe timeout monitoring. |
| I/O Count | Up to 28 I/Os in 32-pin packages, including 21 high-sink outputs - supports direct LED driving, relay control, and robust interfacing with noisy industrial environments. |
| Supply Range | 2.95 V to 5.5 V operating voltage - allows direct connection to 3.3 V or 5 V rails without level-shifting, simplifying power design in mixed-voltage systems. |
| Debug Interface | Single Wire Interface Module (SWIM) - enables full in-circuit debugging and programming using only one pin, reducing PCB footprint and test point count. |
Pinout & Package
LQFP32 (7 × 7 mm) and UFQFPN32 (5 × 5 mm) packages are supported; both use identical pin mapping per DS6210 Rev 13 Section 5.4–5.5. Pin functions include dedicated SWIM, NRST, VCAP, and configurable alternate-function I/Os with remappable peripherals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (NRST) | Active-low reset input | Asynchronous reset with internal pull-up; accepts 10 µs minimum pulse width - ensures reliable initialization under brown-out or ESD events. |
| 2 (PA0) | Port A bit 0 / ADC1_IN0 | Configurable GPIO or analog input for first ADC channel - enables direct sensor connection without external muxing. |
| 3 (PA1) | Port A bit 1 / TIM1_CH1 | Timer capture/compare output or general-purpose I/O - supports edge-triggered input capture for frequency measurement or PWM generation. |
| 4 (PA2) | Port A bit 2 / TIM1_CH2 | Dual-function pin for second TIM1 channel - critical for complementary PWM pair generation with dead-time control in half-bridge drivers. |
| 5 (PA3) | Port A bit 3 / TIM1_CH3 | Third TIM1 channel output - enables three-phase motor control or multi-channel PWM signal routing within single timer resource. |
| 6 (PA4) | Port A bit 4 / TIM1_CH4 | Fourth TIM1 CAPCOM channel - supports synchronized triggering of external circuits or auxiliary PWM signals with phase alignment. |
| 7 (PA5) | Port A bit 5 / SPI_MOSI | Master Out Slave In for SPI interface - allows daisy-chained sensor or actuator communication at up to 8 Mbit/s. |
| 8 (PA6) | Port A bit 6 / SPI_MISO | Master In Slave Out for SPI - enables full-duplex data exchange with external ADCs, DACs, or flash memory. |
| 9 (PA7) | Port A bit 7 / SPI_SCK | SPI clock output - drives synchronous serial peripherals with programmable polarity and phase for legacy device compatibility. |
| 10 (PB0) | Port B bit 0 / UART_TX | UART transmit output - supports asynchronous serial communication, LIN master mode, and IrDA physical layer signaling. |
| 11 (PB1) | Port B bit 1 / UART_RX | UART receive input - includes noise filtering and start-bit detection logic for reliable low-speed serial link recovery. |
| 12 (PB2) | Port B bit 2 / I2C_SCL | I²C clock line - open-drain output with internal pull-up option; supports standard (100 kbit/s) and fast-mode (400 kbit/s) operation. |
| 13 (PB3) | Port B bit 3 / I2C_SDA | I²C data line - bidirectional open-drain with arbitration and clock stretching support for multi-master bus configurations. |
| 14 (PB4) | Port B bit 4 / ADC1_IN1 | Second ADC input channel - enables differential or ratiometric measurements when paired with PA0 reference path. |
| 15 (PB5) | Port B bit 5 / ADC1_IN2 | Third ADC input - supports simultaneous sampling across multiple analog sensors in time-critical acquisition sequences. |
| 16 (PB6) | Port B bit 6 / ADC1_IN3 | Fourth ADC input - configurable as internal temperature sensor input or external voltage monitor for system health diagnostics. |
| 17 (PB7) | Port B bit 7 / ADC1_IN4 | Fifth ADC input - allows integration of potentiometer feedback or battery voltage monitoring without external signal conditioning. |
| 18 (PC0) | Port C bit 0 / ADC1_IN5 | Sixth ADC input - supports external reference voltage measurement for calibration traceability in metrology-grade applications. |
| 19 (PC1) | Port C bit 1 / ADC1_IN6 | Seventh ADC input - enables full 7-channel scan mode for multi-sensor data logging with automatic channel sequencing. |
| 20 (PC2) | Port C bit 2 / SWIM | Single Wire Interface Module debug pin - carries bidirectional debug traffic and programming commands using Manchester-encoded protocol. |
| 21 (PC3) | Port C bit 3 / VCAP | External 1 µF decoupling capacitor connection for internal voltage regulator - stabilizes core supply during dynamic code execution. |
| 22 (VDD) | Power supply (2.95–5.5 V) | Main digital supply rail - powers CPU, memories, and I/Os; requires local ceramic decoupling per datasheet layout guidelines. |
| 23 (VSS) | Ground reference | Digital ground return path - must be connected to low-impedance plane to minimize noise coupling into analog and timing circuits. |
| 24 (VDDA) | Analog power supply | Separate 2.95–5.5 V analog rail - isolates ADC and internal reference from digital switching noise for ±1 LSB accuracy. |
| 25 (VSSA) | Analog ground | Dedicated analog ground - routed separately from digital ground and joined at single point to prevent ground bounce in mixed-signal designs. |
| 26 (PC4) | Port C bit 4 / OSC_IN | Crystal oscillator input - accepts 1–16 MHz parallel-resonant crystals for precise clock source in timing-critical applications. |
| 27 (PC5) | Port C bit 5 / OSC_OUT | Crystal oscillator output - drives external crystal in Pierce configuration; supports optional external clock injection. |
| 28 (PD0) | Port D bit 0 / TIM5_CH1 | General-purpose timer channel - extends timing capability beyond TIM1 for independent PWM or input capture tasks. |
| 29 (PD1) | Port D bit 1 / TIM5_CH2 | Second TIM5 channel - enables dual-output PWM generation for stepper motor microstepping or dual-actuator control. |
| 30 (PD2) | Port D bit 2 / TIM5_CH3 | Third TIM5 channel - supports encoder quadrature decoding or gated pulse counting for position feedback systems. |
| 31 (PD3) | Port D bit 3 / TIM6_ETR | Basic timer external trigger input - synchronizes TIM6 counter with external event such as zero-crossing detection. |
| 32 (PD4) | Port D bit 4 / AWU_IT | Auto-wakeup unit interrupt output - generates wake-up request from low-power halt mode upon timer expiry or external event. |
Key Features
| Feature | Design Value |
|---|---|
| Low-power modes | Wait, active-halt, and halt modes with individual peripheral clock gating - reduces active current to 230 µA at 3.3 V (run mode) and 0.3 µA in halt mode. |
| Robust I/O structure | 21 high-sink I/Os capable of 20 mA per pin - drives LEDs, relays, or MOSFET gates directly without external buffers in cost-sensitive designs. |
| Hardware safety features | Clock security system with monitor, window/independent watchdogs, and power-on/power-down reset - meets IEC 61508 SIL-2 functional safety requirements. |
| True data EEPROM | 640 bytes of byte-erasable EEPROM with 300 kcycle endurance - stores calibration coefficients, device IDs, or usage logs without wear-leveling firmware. |
| Unique 96-bit ID | Factory-programmed serial number per die - enables secure device authentication, license binding, and anti-cloning in OEM production. |
| Flexible clock sources | Four selectable masters (HSE, HSI, LSI, external clock) with runtime switching - supports dynamic power/performance scaling and failsafe clock fallback. |
Applications
| Industrial Sensor Node | Smart Thermostat Controller |
|---|---|
|
Use Scenario: Standalone temperature/humidity sensor with local display and wireless uplink. IC Role / Device Role / Timing Role: Main system controller managing ADC sampling, LCD refresh, button debounce, and UART-based RF module interface. Use Value: Integrated 10-bit ADC, 28 I/Os, and low-power halt mode enable >5-year battery life with periodic wake-up and sensor readout. |
Use Scenario: Residential HVAC control unit with PID loop, fan speed modulation, and user interface. IC Role / Device Role / Timing Role: Real-time motor control processor executing PWM generation, thermal protection logic, and touch-key scanning. Use Value: TIM1's dead-time insertion and complementary outputs allow safe driving of BLDC fan inverters without external gate drivers. |
| Programmable Logic Relay | Energy Meter Front-End |
|
Use Scenario: DIN-rail mounted relay module with configurable I/O mapping and Modbus RTU over RS-485. IC Role / Device Role / Timing Role: Protocol stack executor and discrete I/O manager handling coil activation, contact status reporting, and CRC validation. Use Value: UART with clock output supports synchronous RS-485 transceiver control; 2.95–5.5 V range accommodates wide-input industrial power supplies. |
Use Scenario: Sub-metering node measuring voltage, current, and power factor in commercial building panels. IC Role / Device Role / Timing Role: Analog front-end coordinator acquiring synchronized samples from shunt/CT inputs and computing RMS values. Use Value: ADC scan mode with analog watchdog detects sensor disconnection or overvoltage faults before metering errors occur. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STM8L051F3P6 | Ultra-low-power variant (1.65–3.6 V), 32 Kbytes Flash, no TIM1 advanced timer, 12-bit ADC | Battery-powered IoT endpoints requiring sub-µA sleep but lacking motor control needs | Select when energy harvesting or coin-cell operation is mandatory and PWM complexity is low. |
| STM8AF6266TAY | Automotive-grade (AEC-Q100), 32 Kbytes Flash, CAN 2.0B interface, higher temp range (−40 to 125 °C) | Under-hood automotive body control modules requiring CAN connectivity and extended reliability | Choose for automotive applications needing CAN bus integration and qualification compliance. |
Compared with STM8S903K3B6, the STM8L051F3P6 trades advanced timer capability for deeper sleep efficiency, while the STM8AF6266TAY adds CAN and automotive qualification at the cost of higher BOM complexity and price - making STM8S903K3B6 optimal for industrial control where cost, mixed-signal integration, and moderate performance are balanced.
Availability
STM8S903K3B6 is available at Aetrix Electronics and suitable for industrial sensor nodes, smart thermostat controllers, programmable logic relays, and energy meter front-ends requiring stable component supply across multi-year production cycles.
Supply support for STM8S903K3B6 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 targets cost-sensitive, resource-constrained embedded applications requiring robust analog integration, low-power operation, and mature toolchain support - optimized for rapid development in factory automation and home appliance control.
FAQ
What debug interface does STM8S903K3B6 support?
The STM8S903K3B6 uses the Single Wire Interface Module (SWIM), a proprietary ST protocol requiring only one pin (PC2) for full in-circuit debugging, flash programming, and real-time variable inspection. It operates at up to 2 MHz and is supported by ST Visual Develop, Cosmic C compiler, and ST-LINK/V2 hardware debuggers without additional level shifters or adapters.
Does STM8S903K3B6 support hardware CRC calculation?
No, the STM8S903K3B6 does not include a dedicated hardware CRC peripheral. CRC-8 or CRC-16 computation must be implemented in firmware using the built-in 8-bit ALU and lookup tables. Application notes AN2606 and AN4052 provide optimized assembly routines achieving <10 µs per 8-bit byte on the 16 MHz core.
Can STM8S903K3B6 operate from a 3.3 V supply with full 16 MHz performance?
Yes, the STM8S903K3B6 guarantees full 16 MHz operation down to 2.95 V per DS6210 Rev 13 Table 21. At 3.3 V, typical active current is 2.8 mA (run mode), and all peripherals - including ADC, timers, and communication interfaces - function within specification without derating.
Is there internal flash protection against unauthorized readout?
Yes, the STM8S903K3B6 implements option byte-based readout protection (ROP) with three levels: Level 1 (full readout disable), Level 2 (debug interface disabled), and Level 0 (no protection). ROP is enforced by hardware and survives power cycles; once enabled, flash contents cannot be extracted via SWIM without mass erase, which clears all user code and option bytes.
STM8S903K3B6 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- 32-SDIP (0.400", 10.16mm)
- Series:
- STM8S
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Core Processor:
- STM8
- Core Size:
- 8-Bit
- Speed:
- 16MHz
- Connectivity:
- I2C, IrDA, LINbus, SPI, UART/USART
- Peripherals:
- Brown-out Detect/Reset, POR, PWM, WDT
- Number of I/O:
- 28
- Program Memory Size:
- 8KB (8K x 8)
- Program Memory Type:
- FLASH
- EEPROM Size:
- 640 x 8
- RAM Size:
- 1K x 8
- Voltage - Supply (Vcc/Vdd):
- 2.95V ~ 5.5V
- Data Converters:
- A/D 7x10b
- Oscillator Type:
- Internal
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
STM8S903K3B6 FAQ
1.How can I place an order for STM8S903K3B6 through Aetrix?
Please submit a Request for Quotation (RFQ) for STM8S903K3B6 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for STM8S903K3B6 reliable?
The price and inventory of STM8S903K3B6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STM8S903K3B6 is usually 5 days.
3.What payment methods are accepted for STM8S903K3B6?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STM8S903K3B6 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for STM8S903K3B6?
STM8S903K3B6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your STM8S903K3B6 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for STM8S903K3B6?
For technical support, including STM8S903K3B6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STM8S903K3B6 requirements.
6.How does Aetrix verify that STM8S903K3B6 is sourced from the original manufacturer or authorized distributors?
All STM8S903K3B6 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that STM8S903K3B6 meets industry standards.
7.What is the process for return or replacement of STM8S903K3B6?
All STM8S903K3B6 units undergo pre-shipment inspection (PSI). If there is an issue with STM8S903K3B6, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The STM8S903K3B6 part is unused and in its original packaging.
Return procedure for STM8S903K3B6:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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