STMicroelectronics STM8L050J3M3

Overview

STM8L050J3 from STMicroelectronics is an 8-bit ultra-low-power microcontroller featuring 8 Kbytes of Flash, 256 bytes of data EEPROM with ECC, a BCD real-time clock (RTC) with ±0.5 ppm digital calibration, two 16-bit timers, a 12-bit ADC up to 1 Msps, and dual ultra-low-power comparators - deployed in battery-powered sensor nodes and portable medical devices requiring sub-µA active-halt operation.

For engineers reviewing the STM8L050J3 datasheet, STM8L050J3 pinout, STM8L050J3 application, or STM8L050J3 equivalent, key selection criteria include Halt-mode current (350 nA), RTC accuracy under LSE (±0.5 ppm), 1.8–3.6 V operating range, and SWIM-based non-intrusive debugging support for rapid firmware iteration.

Technical Context

The STM8L050J3 implements a Harvard-architecture STM8 core with 3-stage pipeline, delivering 16 CISC MIPS at 16 MHz while supporting five low-power modes - including Active-halt with RTC (1.3 µA) and Halt (350 nA) - enabled by independent voltage regulator and ultra-low leakage I/Os (50 nA per pin).

Its clock system integrates three oscillators: factory-trimmed 16 MHz RC, 38 kHz low-consumption RC, and external 32 kHz crystal (LSE), all managed via Clock Security System (CSS); the RTC operates autonomously in Halt mode with periodic auto-wakeup capability and LSE security monitoring.

Key Specifications

Pinout & Package

STM8L050J3 is housed in an SO8N package (4.9 × 6 mm, 150 mil body width, 1.27 mm pitch), compliant with ECOPACK® RoHS requirements and optimized for compact PCB layouts in space-constrained wearables and IoT endpoints.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-power 8-bit microcontroller applications.

Compared with STM8L050J3, STM8L052C6 offers scalability at the expense of size and cost, while EFM8LB12F32ES1 trades ultra-low-power integrity for mixed-signal flexibility - making STM8L050J3 optimal for cost-sensitive, battery-limited applications where RTC accuracy and 350 nA Halt current are non-negotiable.

Availability

STM8L050J3 is available at Aetrix Electronics and suitable for smart utility metering, portable medical sensors, industrial wireless sensor nodes, and asset tracking beacons requiring stable component supply across multi-year production cycles.

Supply support for STM8L050J3 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 management ICs, MEMS, and automotive-grade components since 1987.

The STM8L Value line targets ultra-low-power embedded applications - specifically optimizing for battery longevity, RTC precision, and minimal system-level bill-of-materials in cost-sensitive IoT and portable electronics.

FAQ

Does STM8L050J3 support external 1–16 MHz crystals?

No. The STM8L050J3 supports only 32 kHz external crystals (LSE) for RTC operation. Its high-speed oscillator (HSE) input is not implemented - the maximum system clock is derived from the internal 16 MHz RC oscillator or external 32 kHz crystal multiplied via PLL (not available on this variant). This design choice prioritizes ultra-low-power RTC stability over high-frequency flexibility.

Can the 12-bit ADC operate during Low-power Run mode?

Yes. The ADC functions fully in Low-power Run mode (5.1 µA), achieving up to 1 Msps with internal reference. Conversion accuracy remains within ±2 LSB (typical) at VDDA = 3.3 V, and the peripheral clock can be sourced from HSI or LSI - enabling continuous sensor sampling while maintaining sub-µA system-level current draw.

What is the maximum sink current capability of PA0?

PA0 supports 20 mA sink current at VDD = 3.0 V with VOL ≤ 0.4 V, verified per Table 38 in DS12167 Rev 7. This allows direct driving of LEDs or small relays without external drivers - a feature absent on other I/O pins, which are limited to standard GPIO drive strength (max 10 mA sink).

Is SWIM debugging compatible with production firmware lock settings?

Yes. SWIM retains full read/write access to Flash and option bytes even when read-out protection (ROP) level 1 is enabled - allowing secure field updates without exposing source code. However, ROP level 2 permanently disables SWIM access, so level 1 is recommended for production deployments requiring post-deployment firmware upgrades.