STM8S105K4T3C - 16MHz 16KB Flash 32-Pin LQFP | STMicroelectronics
MPN: STM8S105K4T3C ✓ ActiveSTM8S105K4T3C Overview
The STM8S family belongs to the hierarchy of 8-bit microcontrollers, embedded processors, and general-purpose semiconductor control devices. This access-line MCU combines an 8-bit CPU core with timers, UART, SPI, I²C, and a 10-bit ADC, making it suitable for cost-sensitive embedded control, sensor monitoring, communication, and actuator-control designs. Integrated true data EEPROM allows frequently changed parameters to be retained without external nonvolatile memory.
Key features of the STM8S105K4T3C include up to 16 KB of Flash memory, 2 KB of SRAM, 16 MHz maximum operating frequency, 38 I/O ports, a 10-bit ADC, and support for the STM8 communication peripherals. The 2.95 V minimum operating voltage supports systems designed around 3.3 V rails, while the 5.5 V maximum provides compatibility with conventional 5 V industrial and embedded control environments.
The device is a medium-density member of the STM8S105x4/6 access line and is described in the STM8S family reference manual. Its combination of integrated EEPROM, serial interfaces, timers, and ADC functionality reduces external component count in compact control systems. The LQFP-32 package provides exposed leads that support conventional PCB assembly and inspection processes.
Typical applications include industrial sensor modules, building-control endpoints, appliance controllers, small motor-control boards, communication transceivers, and low-cost embedded automation products. When designing a board, confirm the exact pin multiplexing, oscillator requirements, reset circuit, and peripheral assignment against the manufacturer datasheet before finalizing the PCB.
A key design consideration is the difference between the STM8S105K4 and STM8S105K6 devices. The K4 selection provides 16 KB of Flash, while related K6 options provide higher memory capacity and may require different firmware planning. Use the Request a Quote form on this page for current sourcing, price, stock, and lead-time information.
Drop-in alternatives for STM8S105K4T3C — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with STM8S105K4T3C (same form factor and footprint) — differing in ADC Resolution, Product Family, Supply Voltage Range.
STM8S105K4T6C
✅ Drop-InContact for price
View Datasheet →STM8S105K4T6CTR
✅ Drop-In📋 Reference alternative (not in catalog)
STM8S105K6T3C
✅ Drop-In📋 Reference alternative (not in catalog)
STM8S105K6T6C
✅ Drop-InContact for price
View Datasheet →STM8S105K6T3
✅ Drop-In📋 Reference alternative (not in catalog)
STM8S105K4T3C Maximum Ratings & Electrical Characteristics
| Microcontroller Type | 8-bit microcontroller |
| Product Family | STM8S105 access line |
| Maximum Clock Frequency | 16 MHz |
| Flash Program Memory | 16 KB |
| RAM | 2 KB |
| Integrated Data EEPROM | Present |
| Supply Voltage Range | 2.95 V to 5.5 V |
| ADC Resolution | 10 bits |
| I/O Ports | 38 |
| Package Type | 32-pin LQFP |
| Temperature Range | -40 °C to +125 °C |
| UART | Available |
| SPI | Available |
| I²C | Available |
| Timers | Available |
| Mounting Type | Surface Mount |
| Lifecycle Stage | Active |
STM8S105K4T3C 32-pin lqfp Pin Configuration Guide
Pin configuration for STM8S105K4T3C (32-pin lqfp package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for STM8S105K4T3C.
Refer to the datasheet for full pin configuration.
Typical Applications
STM8S105K4T3C is suitable for 6 applications: Industrial Sensor Monitoring, Building Control Endpoint, Appliance Control Module, Compact Communications Module, Small Motor and Actuator Control, Low-Cost Data Acquisition Node.
Industrial Sensor Monitoring
The STM8S105K4T3C suits compact industrial sensor nodes that must measure analog inputs and communicate results over a local serial link. Its 10-bit ADC handles many pressure, temperature, level, and position sensing interfaces, while 38 I/O ports provide control and alarm functions. The 16 MHz clock supports responsive sampling and digital filtering, and 2 KB of RAM is useful for short acquisition buffers and protocol handling. With operation specified from -40 °C to +125 °C, it can serve industrial equipment where the system also needs UART, SPI, or I²C connectivity. Integrated EEPROM can retain calibration factors, sensor offsets, and configuration identifiers without an external memory component.
Recommended
Building Control Endpoint
The STM8S105K4T3C is appropriate for building-control endpoints that combine a local sensor interface with serial connectivity. A room controller can use the 10-bit ADC for analog environmental sensors, GPIO for relays and status indicators, and UART or RS-485-based communication for a supervisory controller. The STM8S family includes timers for periodic sampling and communication timing, plus I²C and SPI for sensors and local memories. Its 2.95 V to 5.5 V range supports both 3.3 V electronics and legacy 5 V field interfaces, provided signal levels are checked. The integrated EEPROM is valuable for storing room configuration, calibration, and commissioning records.
Recommended
Appliance Control Module
The STM8S105K4T3C fits appliance-control modules that coordinate buttons, displays, heaters, valves, motors, and safety inputs. The 8-bit architecture and 16 MHz clock are well matched to dedicated control tasks, while timers and PWM-capable peripherals can simplify actuator sequencing. UART and I²C permit connection to a display, sensor module, or accessory controller, and the integrated EEPROM can retain configuration and usage counters. A 2.95 V minimum supply supports 3.3 V control boards, while the 5.5 V maximum maintains compatibility with 5 V system rails. Firmware must include suitable watchdog, fault-state, and brownout handling for appliance environments.
Recommended
Compact Communications Module
The STM8S105K4T3C can act as the protocol controller in a compact communications module requiring UART, SPI, or I²C connectivity. At 16 MHz, it can handle lightweight protocol framing, data acquisition, status monitoring, and local configuration while offloading the host from repeated device transactions. The integrated true data EEPROM is useful for addresses, calibration values, and network parameters, and the 32-pin LQFP package provides a practical footprint for conventional PCB assembly. Designers should budget the 16 KB Flash and 2 KB RAM carefully if buffering or encryption workloads are substantial. The K6 variants become attractive when protocol libraries, firmware updates, or security features require additional program memory.
Recommended
Small Motor and Actuator Control
The STM8S105K4T3C is suitable for compact actuator controllers where timers, GPIO, and serial control are more important than high processor performance. It can sequence a small motor, solenoid, valve, or stepper actuator while reading limit switches and analog feedback. The 16 MHz clock provides useful timing margin, and the ADC can monitor current, position, or sensor-derived feedback at 10-bit resolution. The 38 available I/O ports reduce the need for expanders in multi-axis or discrete-control designs. Because motor environments introduce electrical noise and inductive transients, external drivers, protection, filtering, and a robust power design remain necessary even when the MCU itself supports the full -40 °C to +125 °C range.
Recommended
Low-Cost Data Acquisition Node
The STM8S105K4T3C can serve as a low-cost data-acquisition node when measurements are modest and the design requires local communications rather than high-speed processing. The 10-bit ADC supports many process and environmental inputs, while 2 KB of RAM provides limited working space for sampled values and protocol buffers. UART, SPI, and I²C enable connection to external sensors, storage, or a host controller. Integrated EEPROM supports calibration tables and sequential node identifiers, reducing board complexity. Keep acquisition timing deterministic by using a hardware timer for sampling and account for the 16 KB Flash limit when including drivers, communications, and application code. The same MCU can support both 3.3 V and 5 V installations within its 2.95 V to 5.5 V supply range.
Recommended
Recommended Products Summary
Engineering reference data for STM8S105K4T3C — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | STM8S105K4T6C | STM8S105K4T6CTR | STM8S105K6T3C | STM8S105K6T6C | STM8S105K6T3 |
|---|---|---|---|---|---|---|
| Package | 32-pin LQFP | 32-pin LQFP | 32-pin LQFP | 32-pin LQFP | 32-pin LQFP | 32-pin LQFP |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Maximum Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| Integrated Data EEPROM | Present | Present | Present | Present | Present | Present |
Key Differentiators
- Lower memory configuration for firmware-constrained designs (vs STM8S105K6T3C)
- Same core clock as related family alternatives (vs STM8S105K6T6C)
- Compact integrated feature set (vs STM8S105K4T6CTR)
Design Notes
Design the supply network for the full 2.95 V to 5.5 V operating range rather than assuming a nominal rail is sufficient. Place the MCU's required bypass capacitors directly at the supply and ground pins, keep analog and digital return paths controlled, and account for startup current when selecting the regulator. If the board must operate from either 3.3 V or 5 V, verify every connected interface's input thresholds and output levels; the MCU supply range alone does not make mixed-voltage peripherals safe to connect directly.
Assign pins from the manufacturer pin-description table before routing, because several STM8S105x4/6 functions are multiplexed. Reserve the oscillator, reset, and programming-interface pins according to the reference circuit, and keep sensitive analog inputs away from switching nodes and high-current return paths. The 32-pin LQFP footprint leaves more routing space than smaller packages, but correct escape routing for the clock and debug functions remains essential. Verify the alternate-function mapping in the STM8S family reference manual RM0016 for every selected peripheral.
Do not treat related STM8S105 K4 and K6 order codes as automatically interchangeable. Check Flash capacity, RAM, temperature grade, packing method, and package dimensions against the ordering table. Firmware built for a K6 part may exceed the 16 KB Flash available in the STM8S105K4T3C, and a tape-and-reel suffix may not match a tray-based assembly process. Validate the complete pinout, bootloader behavior, and peripheral instance set before approving a substitution.
Although the STM8S105K4T3C is specified from -40 °C to +125 °C, the complete assembly must remain inside the MCU's junction-temperature limit. Place the LQFP on a thermal path appropriate to its dissipation and avoid enclosing it in a poorly ventilated enclosure. Industrial systems should calculate worst-case dissipation from the actual supply and clock conditions rather than relying on a nominal operating point. Include ambient-temperature margin and account for nearby regulators, power converters, and shared copper areas that can heat the board.
Compliance Information
The manufacturer product page identifies the STM8S105K4 family, but the available product information does not explicitly state the requested compliance fields.