STM8S003K3T6C — 8-Bit STM8 Value Line MCU in LQFP-32 for BLHeli_S ESC and BMS Applications

The STM8S003K3T6C is the LQFP-32 packaged variant of the popular STM8S003 Value Line family — delivering the same 8-bit STM8 core at 16 MHz with 8 KB Flash and 1 KB SRAM, but in a larger LQFP-32 (7×7 mm) footprint that provides 28 GPIO pins. With 12 more I/O pins than the TSSOP-20 variant, it is ideal for multi-motor ESC control, BMS cell-monitoring with external multiplexing, PDB controller with multiple sensor inputs, and addressable LED strip drivers requiring additional signal channels.

Part Number Decoded — Field by Field

Quick Specifications

Product Overview

The STM8S003K3T6C is the LQFP-32 member of the STM8S003 Value Line family. While retaining the same 8 KB Flash, 1 KB SRAM, and 128-byte EEPROM as the TSSOP-20 variant, the larger package unlocks 28 GPIO pins — a 75% increase over the 16 pins of the TSSOP-20. This additional I/O is critical for applications that need to control more MOSFET gate-driver signals, read multiple ADC channels simultaneously, or drive multiple LED strings in parallel.

In the drone ecosystem, the K3 variant serves in more complex BLHeli_S ESC designs that integrate onboard current sensing, voltage monitoring, and LED control on a single MCU. For BMS applications, the extra GPIOs enable direct connection to cell-balancing MOSFETs and multiple temperature sensors without external I/O expanders. For PDB controllers, it can simultaneously monitor 4 ESC current channels, main battery voltage, and 5V/12V regulator outputs while driving status LEDs.

Key Features & Benefits

28 GPIO Pins in LQFP-32 — Room for Multi-Channel ESC Control

With 28 GPIOs available after reserving SWIM, NRST, and VCAP, the K3 variant can control a dual-motor ESC (12 PWM channels for two 3-phase inverters) from a single MCU — enabling compact coaxial drone or tilt-rotor motor controller designs. Alternatively, it can dedicate 6 pins to the MOSFET bridge, 4 to ADC current sensors, 2 to UART, and still have 16 pins for LED strips and status indicators.

Hand-Solderable 0.8 mm Pitch — Prototype-Friendly

The LQFP-32 package with 0.8 mm pitch is the largest practical QFP pitch available — making it hand-solderable with a basic fine-tip iron or hot-air station. This is significantly more accessible than QFN or BGA packages, reducing the barrier for drone hobbyists and small-batch manufacturers to design custom ESC and BMS boards.

4-Channel 10-Bit ADC — Multi-Channel Voltage Monitoring

The ADC provides 4 multiplexed channels with 10-bit resolution at up to 1 Msps — sufficient for scanning individual LiPo cell voltages in a BMS application at 4.9 mV resolution (5V reference). With the extra GPIOs, external analog multiplexing can be controlled directly from the MCU to expand the effective ADC channel count for 6S-8S battery packs.

Target Applications

Dual-Motor Drone ESC (Coaxial / Tilt-Rotor)

The 28 GPIOs enable a single STM8S003K3 to drive two independent BLDC motors — perfect for coaxial drone platforms (where two motors share a single arm) or tilt-rotor VTOL aircraft where differential motor control is required. Two advanced timer channels (though only one advanced timer is available, general-purpose timers can generate PWM) provide the 12 gate-drive signals for two 3-phase inverters.

Advanced BMS with Cell Balancing Control

The extra GPIOs directly drive cell-balancing MOSFETs, temperature sensor inputs, and protection FET gate drivers — building a complete 3S–6S BMS controller without external I/O expansion. The 10-bit ADC scans cell voltages through an external multiplexer, and the UART communicates pack status (SOC, SOH, cell voltages, temperature) to the flight controller or OSD.

Full-Featured PDB Telemetry Controller

Monitors 4× ESC current sensors, main battery voltage, 5V/12V BEC output, and ambient temperature — all simultaneously through ADC scanning. Communicates aggregated power telemetry (total current, Watt-hours consumed, per-ESC current) to the flight controller via UART, providing the data for Betaflight/iNav OSD power elements.

Frequently Asked Questions

Is the STM8S003K3T6C code-compatible with the TSSOP-20 STM8S003F3P6?

Yes, fully. Both share the same STM8 core, Flash map, peripheral register map, and interrupt vectors. BLHeli_S firmware compiled for the F3 variant runs unmodified on the K3 variant — the only difference is that additional GPIO pins become available for application use. Pin assignments differ due to the different package, but the peripheral-to-pin mapping follows the same alternate-function scheme defined in RM0016.

Can BLHeli_S run on the LQFP-32 variant?

Yes, but most commercial BLHeli_S ESCs use the smaller TSSOP-20 package for cost and PCB area savings. The LQFP-32 variant is typically used in custom ESC designs that require additional onboard features (current sensing, LED control, dual motors) beyond what the 16-pin TSSOP-20 can accommodate. The additional I/O pins are unused by the standard BLHeli_S firmware but can be utilized by custom firmware forks.

Ordering Information

Design Resources

• Datasheet (DS7147): STM8S003F3 / STM8S003K3 — Complete specs covering both TSSOP-20 and LQFP-32 package variants, including LQFP-32 mechanical drawings, PCB land pattern, and thermal characteristics.
• Reference Manual (RM0016): STM8S Series — Register-level documentation with alternate-function mapping for LQFP-32 pinout.
• BLHeli_S GitHub: bitdump/BLHeli — Open-source BLHeli_S firmware, although targeted at TSSOP-20, the source can be adapted for LQFP-32 pinout.
• STVD (ST Visual Develop): Free IDE with COSMIC C compiler and SWIM debug support — recommended for custom STM8 ESC and BMS firmware development.
• Application Note AN2860: EMC Design Guide for STM8 — Layout recommendations for the LQFP-32 package in high-noise ESC and motor-drive environments.

Request a Quote

SUPERB Automation supplies genuine STMicroelectronics STM8S003K3T6C LQFP-32 MCUs with full traceability and batch-level QA documentation. The K3 LQFP-32 variant provides the same proven STM8S003 core with 75% more GPIO — ideal for custom drone ESCs and BMS designs that need more I/O without moving to a more expensive 32-bit MCU. Whether you need prototype quantities for ESC firmware development or production volumes for drone BMS and PDB controller manufacturing, we source through verified channels with competitive lead times. Contact us with your target quantity, delivery date, and any special packaging or marking requirements — we'll respond with a detailed quotation within 24 hours.