STM8L050J3M3 STMicroelectronics Ultra-low-power 8-bit Microcontroller MCU 8KB Flash SO8N

STM8L050J3M3 Product Overview

The STM8L050J3M3 is an ultra-low-power value line 8-bit microcontroller from STMicroelectronics, featuring an enhanced STM8L core operating up to 16 MHz (16 MIPS). The chip integrates 8 KB Flash, 1 KB RAM, and 256 bytes of data EEPROM with ECC, with five ultra-low-power modes down to 350 nA Halt, along with a built-in 12-bit ADC and 4-channel DMA controller. With rich analog peripherals, flexible communication interfaces, and a compact SO8N package, the STM8L050J3M3 is ideal for battery-powered, industrial sensor, and IoT node applications where power, cost, and space constraints are critical.

STM8L050J3M3 Core Features

Ultra-Low-Power Architecture: Five low-power modes including Wait, Low-power run (5.1 µA), Low-power wait (3 µA), Active-halt with RTC (1.3 µA), and Halt (350 nA); ultra-low leakage per I/O: 50 nA; fast wakeup from Halt: 5 µs Enhanced STM8L Core: 16 MHz CPU delivering up to 16 MIPS, leveraging Harvard architecture and 3-stage pipeline, maintaining advantages of CISC architecture with improved code density and 24-bit linear addressing space Integrated Memory: 8 KB Flash program memory, 1 KB RAM, and 256-byte data EEPROM with ECC, supporting up to 100k erase/write cycles with flexible write and read protection modes 12-bit ADC with DMA: Built-in 12-bit SAR ADC up to 1 Msps / 4 channels, paired with a 4-channel DMA controller supporting ADC, SPI, I2C, USART, and timers for efficient sensor data acquisition, offloading the CPU Rich Analog Resources: Integrated two ultra-low-power comparators (one fixed threshold, one rail-to-rail), both with wakeup capability Flexible Communication Interfaces: Supports USART, Fast I2C (400 kHz SMBus/PMBus), SPI, and IrDA infrared communication for easy connectivity with various peripherals Rich Timer Resources: Two 16-bit general-purpose timers (supporting input capture, output compare, PWM, quadrature encoder), one 8-bit basic timer, beeper timer, and two watchdogs (Window + Independent) Low-Power RTC: BCD calendar with alarm interrupt, digital calibration with ±0.5 ppm accuracy, auto-wakeup from Halt with periodic interrupt Compact SO8N Package: Small SO8N footprint with up to 6 user I/Os, all mappable on interrupt vectors, offering excellent pin utilization for space-constrained portable devices and miniature sensor modules High Reliability Design: Built-in POR, 5-level selectable BOR, programmable voltage detector (PVD); I/O ports feature latch-up immunity and ESD protection Wide Voltage & Temperature Range: Operating voltage from 1.8 V to 3.6 V; ambient temperature range -40 °C to +125 °C for harsh industrial and outdoor environments Fast Development Support: Integrated SWIM debugging module supporting non-intrusive in-application debugging and ultra-fast Flash programming; also supports bootloader via USART

STM8L050J3M3 Applications

Industrial Sensor Nodes: Ideal for industrial field sensor signal acquisition and simple control tasks (temperature, pressure, proximity), with wide temperature range ensuring reliable operation in extremes Battery-Powered Devices: Smart metering (water, gas, heat meters), remote controls, portable medical monitors, and other battery-powered devices highly sensitive to power consumption Smart Home & IoT: Smart lighting, access cards, smart printer cartridges, home automation nodes, and other compact consumer applications Consumer Electronics & Toys: Electronic toys, small accessories, e-bike controllers, battery chargers, and other cost-sensitive and power-sensitive products Embedded Systems: Simple data acquisition modules, sensor interface boards, low-pin-count embedded control nodes

STM8L050J3M3 Key Advantages

Extreme Low Power for Long Battery Life: 350 nA Halt, 5.1 µA Low-power run, and 50 nA leakage per I/O enable multi-year operation from a single coin cell, significantly reducing maintenance DMA Boosts Efficiency: 4-channel DMA controller enables direct data transfer between peripherals and memory, freeing up CPU resources and further optimizing system efficiency in low-power scenarios High Integration in Small Package: SO8N package integrates ADC, DMA, EEPROM, and multiple comm interfaces with up to 6 user I/Os, greatly saving PCB area and BOM costs Rich Analog Peripherals: 12-bit ADC, two comparators, and low-power RTC provide exceptional flexibility for sensor acquisition and threshold detection Wide-Temp Industrial Reliability: -40 °C to +125 °C range combined with 5-level BOR and ESD protection ensures stable, reliable operation in outdoor and industrial fields Flexible Power/Performance Mix: Five low-power modes and high-performance 16 MHz operation allow on-demand switching, using exactly the energy needed for the task Mature STM8 Ecosystem: Leveraging the classic STM8S/STM8L architecture with rich documentation and active community, supported by low-cost SWIM debugging tools and reference designs, simplifying development Value Line Cost Advantage: As a member of the STM8L value line, delivers ultra-low-power performance and rich peripherals at a highly competitive cost Fast Wake-up for Instant Response: As fast as 5 µs wake-up from Halt mode rapidly handles interrupts, processes data, and re-enters sleep, further compressing average power consumption

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FAQ:

1. What is the STM8L050J3M3 and its key specifications?
   The STM8L050J3M3 is an ultra‑low‑power 8‑bit microcontroller from STMicroelectronics based on the STM8L core at up to 16 MHz. It provides 8 KB of Flash program memory, 1 KB of SRAM, and 256 bytes of true data EEPROM. On‑chip peripherals include two comparators, general‑purpose timers (TIM2, TIM3, TIM4), an RTC with calendar, and communication interfaces: USART, SPI, I2C. This MCU does not include an ADC, DAC, LCD controller, DMA, or AES module. It is housed in a tiny SO8N package (4.9 mm × 3.9 mm) with 5 I/O pins and operates over an extended ‑40 °C to +125 °C temperature range. This is the most streamlined, cost‑sensitive member of the STM8L family, designed for extremely space‑constrained, battery‑powered applications that require only basic digital control, high‑temperature tolerance, and reliable non‑volatile storage.

2. How does the STM8L050J3M3 differ from the STM8L051F3P6?
   Both are ultra‑low‑power STM8L devices with the same Flash/RAM/EEPROM sizes. The STM8L051F3P6 adds a 12‑bit ADC (up to 10 channels), while the STM8L050J3M3 has no ADC. The packages also differ: the F3P6 uses a TSSOP‑20 package with 16 I/O pins, whereas the J3M3 comes in an ultra‑small SO8N with only 5 I/O pins and a much wider temperature range of ‑40 °C to +125 °C (F3P6 is ‑40 °C to +85 °C). Choose the J3M3 when you need the smallest possible footprint, high‑temperature operation, and can work without an ADC; choose the F3P6 when you need more I/O and analog voltage measurement.

3. What is the difference between STM8L050J3M3 and STM8L101F3U6?
   Both lack an ADC and DAC, but they differ in several ways. The STM8L050J3M3 provides 256 bytes of true EEPROM, while the L101F3U6 has no EEPROM and relies on Flash emulation. The J3M3 also includes an RTC with calendar, which the L101 lacks. In terms of package, the J3M3 uses a very small SO8N with 5 I/O pins and operates at up to +125 °C, whereas the L101F3U6 comes in a UFQFPN20 (3×3 mm) with 16 I/O pins and a standard 85 °C limit. Choose the J3M3 when you need a tiny, high‑temperature, EEPROM‑equipped controller; choose the L101F3U6 for more I/Os and a slightly lower cost without EEPROM or RTC.

4. What ultra‑low‑power modes does the STM8L050J3M3 offer?
   It delivers excellent power efficiency. In Run mode at 1 MHz, the current is about 195 µA. It drops to 5.1 µA in Low‑power run mode. Active‑halt mode with the RTC running draws only 1.0 µA, and full Halt mode consumes as little as 0.35 µA (typical). The fast wake‑up from these modes makes the chip ideal for coin‑cell‑powered devices that must run for years on a single battery.

5. Can the STM8L050J3M3 drive a brushless DC motor?
   No. The STM8L050J3M3 does not include an advanced‑control timer with complementary PWM outputs and dead‑time insertion. It provides general‑purpose timers (TIM2, TIM3, TIM4) that can generate standard PWM signals for DC motors, servo control, or LED dimming. For three‑phase BLDC motor control, an external gate driver with built‑in dead‑time is required, or you can switch to an STM8S/STM32 series MCU with a motor‑control timer.

6. Does the STM8L050J3M3 have an ADC?
   No. The STM8L050J3M3 does not include an analog‑to‑digital converter. It relies on two analog comparators for simple threshold detection. If analog voltage measurement is required, an external ADC chip must be added, or you can use a variant from the STM8L051/052/151/152 series that provides a 12‑bit ADC.

7. How much memory does the STM8L050J3M3 have?
   It provides 8 KB of Flash program memory, 1 KB of SRAM, and 256 bytes of true data EEPROM. The EEPROM offers reliable, high‑endurance storage for calibration constants or user settings without wearing out the Flash. This memory configuration is well‑suited for highly optimized, single‑purpose firmware in ultra‑compact devices.

8. What package does the STM8L050J3M3 use and how many I/O pins are there?
   It comes in an extremely small SO8N package (4.9 mm × 3.9 mm, 1.27 mm lead pitch) and provides 5 general‑purpose I/O pins. The 5 I/O lines are heavily multiplexed with the communication interfaces and comparator inputs. This tiny package is ideal for space‑critical designs such as miniature sensors, medical wearables, and high‑temperature probes.

9. What is the supply voltage range of the STM8L050J3M3? Can it be powered by a coin cell?
   The operating voltage is 1.8 V to 3.6 V, which is perfectly suited for a single CR2032 coin cell or two alkaline AAA batteries. The MCU includes a low‑voltage reset (BOR) with programmable thresholds to ensure safe operation as the battery discharges. 5 V is not supported; a voltage regulator is required if 5 V components are present.

10. How to program and debug the STM8L050J3M3? What are its typical applications?
    Programming and debugging use the single‑wire SWIM interface (shared with a GPIO pin), requiring only one data line plus reset and ground. A low‑cost ST‑LINK/V2 is the standard tool. Firmware can be developed with STVD + Cosmic C or the open‑source SDCC compiler, and ST provides the STM8L15x standard peripheral library. Typical applications include high‑temperature sensor nodes, automotive under‑hood monitors, tiny battery‑powered beacons, simple logic controllers, and space‑constrained IoT endpoints that need a proven 8‑bit core, true EEPROM, and a very small footprint without analog measurement requirements.