STM32L100R8T6ATR Ultra-Low-Power MCU

The STM32L100R8T6ATR is an ultra-low-power 32-bit microcontroller from STMicroelectronics, based on the Arm Cortex-M3 processor core. Operating at up to 32 MHz, this MCU is part of the STM32L100 Value Line family, designed for applications that require high performance with minimal energy consumption. With 64 KB of Flash memory and 8 KB of RAM, and a wide operating voltage range (1.8 V to 3.6 V), the STM32L100R8T6ATR is suitable for industrial control, smart metering, medical devices, and battery-powered applications. The device is offered in the LQFP64 (10 mm × 10 mm) package with tape-and-reel (TR) shipping format.

Technical Specifications

Core: Arm 32-bit Cortex-M3 with MPU, operating at 32 MHz maximum frequency. Flash memory: 64 KB with ECC (Error Correction Code). RAM: 8 KB. Backup registers: 20 bytes. Power supply: 1.8 V to 3.6 V. Low-power modes: sleep, stop, and standby modes with consumption as low as 0.35 μA in standby. The device includes a real-time clock (RTC) with calendar functionality and backup registers. Communication interfaces: up to 2 I2C interfaces (SMBus/PMBus), 2 SPI interfaces (16 Mbit/s), 2 USART interfaces (ISO 7816, LIN, IrDA, modem control), and a USB 2.0 full-speed interface. Analog peripherals: 12-bit ADC with up to 20 channels and 1 μs conversion time, and a 12-bit DAC (one channel). Timers: three 16-bit timers with up to 4 IC/OC/PWM channels, one 16-bit basic timer, and two watchdogs. I/O: up to 51 I/O lines (all 5 V tolerant) in the LQFP64 package. CRC calculation unit for data integrity. Operating temperature range: -40°C to +85°C (industrial grade).

Key Features

• 32-bit Arm Cortex-M3 core, up to 32 MHz

• 64 KB Flash memory with ECC

• 8 KB SRAM

• Ultra-low power consumption: 0.35 μA in standby mode

• Wide supply voltage: 1.8 V to 3.6 V

• 12-bit ADC (20 channels, 1 μs conversion)

• 12-bit DAC (1 channel)

• Real-time clock (RTC) with calendar and alarm

• USB 2.0 full-speed interface

• I2C, SPI, and USART interfaces

• 51 5V-tolerant I/O pins in LQFP64 package

• Operating temperature: -40°C to +85°C

Ultra-Low-Power Architecture

The STM32L100 Value Line is built on an ultra-low-power process technology that reduces both dynamic and leakage current. The device features multiple power-saving modes: Sleep mode (CPU stopped, peripherals running), Stop mode (all clocks stopped, contents preserved, wake-up from any EXTI line or RTC), and Standby mode (lowest consumption, 0.35 μA typical, with backup registers retained). The dynamic run current is typically 9.2 mA at 32 MHz and 3.6 V. The internal voltage regulator can be configured for different performance and power trade-offs. The RTC runs from a separate 32 kHz oscillator and continues to operate even in Stop mode, allowing time-stamped wake-ups without consuming significant power.

Industrial Applications

The STM32L100R8T6ATR is designed for applications that require a balance of processing capability and power efficiency. Typical applications include industrial PLC I/O modules, process instrumentation (pressure, temperature transmitters), smart sensors and actuators, programmable controllers, and building automation devices (thermostats, lighting controls). The 12-bit ADC and DAC are suitable for closed-loop control systems and data acquisition. The 5V-tolerant I/O pins simplify interfacing with industrial sensors and actuators that operate at 5 V logic levels, without requiring external level shifters.

Development and Programming

The STM32L100R8T6ATR is supported by STMicroelectronics’ STM32Cube ecosystem, including the STM32CubeMX configuration tool and STM32CubeL1 firmware package (HAL and low-layer drivers). Development can be performed using Keil MDK, IAR EWARM, or ST’s free STM32CubeIDE. Debugging is supported via the Serial Wire Debug (SWD) interface, requiring only two pins for debug access. The MCU also includes a built-in bootloader supporting UART and USB for in-system programming without an external debugger.

Peripherals and Connectivity

The device integrates a comprehensive set of peripherals. The 12-bit ADC offers up to 20 input channels, scan mode, and analog watchdog. The 12-bit DAC (one channel) can be used for analog output generation or as a reference for external circuits. Communication interfaces include USB 2.0 full-speed (12 Mbit/s) with integrated transceiver (no external USB PHY required). The USART interfaces support LIN, IrDA, and ISO 7816 smart card protocols. The SPI interface operates up to 16 Mbit/s. The I2C interfaces support SMBus and PMBus. Timers include a 16-bit advanced-control timer with complementary PWM outputs for motor control, as well as general-purpose timers for waveform generation and input capture.

Package and Ordering

The STM32L100R8T6ATR is supplied in an LQFP64 (Low-Profile Quad Flat Package) with 64 pins, 10 mm × 10 mm body size, 0.5 mm pitch. The “TR” suffix indicates tape-and-reel packaging for automated assembly, with 1,000 units per reel (typical). The operating temperature range is -40°C to +85°C. The device is RoHS compliant and halogen-free. For engineering samples, the STM32L100R8T6 (non-TR) is available in tray packaging.

Environmental and Compliance

The STM32L100R8T6ATR is manufactured using a lead-free process (NiPdAu or SnAgCu pads). It is compliant with the European Union Directive 2011/65/EU (RoHS). The device meets JEDEC standards for moisture sensitivity (MSL 3). ESD protection is provided on all pins per JEDEC JS-001 and JS-002 standards.

Conclusion

The STM32L100R8T6ATR MCU offers an optimal combination of low power consumption, adequate performance (32 MHz Cortex-M3), and integrated peripherals for industrial and embedded applications. Its 64 KB Flash, 8 KB RAM, 12-bit ADC/DAC, and USB interface make it a suitable choice for cost-sensitive but power-conscious designs requiring reliable operation over the industrial temperature range.