An Industry Race to the Bottom
Low-power MCUs have become omnipresent, with good reason: the explosion in AIoT and wearable tech has created a great demand for minimizing energy consumption in virtually every application. This month’s Datasheet gallery represents just some of the great diversity of low-power MCUs available on the market today.
Low-power MCU” might be the second most ubiquitous phrase in the embedded systems industry, today—second only to “AI,” I would guess, and perhaps only slightly more widespread than the even more appealing “ultra-low-power MCU.” I’ve seen at least one major manufacturer touting “extreme low power,” and I’m sure that, in a year or two, we’ll have one or two more popular adjectives to describe this exploding trend in microcontroller technology.
I don’t mean to sound jaded! The demand for MCUs that use as little energy as possible is more than understandable. As IoT and wearable technology continue to grow at a tremendous speed, so too does the need for devices with long battery lifespans. No one wants to be glued to their chargers, and reducing energy consumption is a bonus. And outside of the home, in embedded applications within various industries, the desire to minimize energy usage needs, I assume, no explanation.
So we bring you nine MCUs, all from industry giants, for which low-power, or ultra-low-power, or hyper-nano-extreme-low-power, is a key feature. Each of these devices were released within the last 12 months, and there is some range in applications and specializations: from general-purpose offerings, to those geared toward connected smart devices in medical applications, to products suited for long-range wireless solutions, to sensing applications, to highly configurable devices, and more. My usual disclaimer applies, perhaps more than ever: the field of low-power applications is huge, the devices in this field are many, and hence nine products can only represent the tiniest sliver of what’s available. Still, I aimed to bring you some of the latest from some of the biggest names, and hope that this column might prove a useful start in your search for the right low-power MCU for your latest project.
Industry-Leading Capacitive Sensing Solution
Infineon’s PSoC 4000T is a best-in-class low-power capacitive sensing solution with unsurpassed signal-to-noise ratio, liquid tolerance, and multi-sense capabilities coupled with industry-leading reliability and robustness. PSoC 4000T microcontrollers expand the PSoC 4 product family of Arm Cortex-M0+ based microcontrollers and feature Infineon’s 5th Generation high-performance CAPSENSE capacitive sensing technology. Infineon’s 5th Generation CAPSENSE technology provides 10x higher SNR (signal-to-noise ratio) performance with 10x lower consumption than previous generations of CAPSENSE.
- 32-bit MCU subsystem: 48-MHz Arm Cortex -M0+ CPU with single-cycle multiply; Up to 64 KB of flash with read accelerator; Up to 8 KB of SRAM
- 5th generation CAPSENSE technology; supports both, self and mutual capacitive sensing techniques.
- 16 sensor inputs: Up to 16 self-capacitive inputs; Up to 64 mutual-capacitive inputs
- Up to 21 Programmable pins
- Two 16 bit-time/counter/pulse-width modulator (TCPWW) blocks
- Two configurable serial communication blocks (SCBs) to support I2C, SPI or UART interface.
- Best-in-class signal-to-noise ratio
An MCU Family for Multi-Sensor Systems
The PIC18-Q20 family of MCUs offers configurable peripherals and advanced communication interfaces and supports multiple voltage domains for embedded systems that have several sensors. These MCUs are equipped with I3C modules that have a fast communication rate, a high-speed 10-bit Analog-to-Digital Converter with Computation (ADCC), capacitive touch sensing and an 8-bit signal routing port to interconnect digital peripherals. This product family easily interfaces across multiple voltage domains without external components and supports 1V operation for I3C communication. With I3C support and the integrated level shifters, PIC18-Q20 MCUs are suitable for sensor interfacing in embedded designs with multiple voltage domains.
- C Compiler Optimized RISC Architecture
- Operating Speed: DC—64MHz clock input; 62.5ns minimum instruction cycle
- Four Direct Memory Access (DMA) Controllers
- Vectored Interrupt Capability
- 128-Level Deep Hardware Stack
- Low-Current Power-on Reset (POR)
- Configurable Power-up Timer (PWRT)
- Brown-out Reset (BOR)
- Low-Power BOR (LPBOR) Option
- Windowed Watchdog Timer (WWDT)
Flash-Embedded 1T 8051-based MCUs
The Low Power MUG51 series is a Flash-embedded 1T 8051-based low-power microcontroller. It runs up to 7.3728 MHz with 16 Kbytes embedded Flash memory, 1 Kbytes embedded SRAM, 4 Kbytes Flash loader memory (LDROM), 1.8V ~ 5.5V operating voltage, and -40°C ~105°C operating temperature. The Low Power MUG51 series supports enhanced low current consumption at 200μA while CPU Power-on before Flash memory is initialized. Its low-power feature makes it suitable for battery-free device which harvests power from the magnetic field of coil such as stylus pen powered by EMR (Electro-magnetic Resonance) technology and RFID card.
- Voltage range: 1.8V to 5.5V
- Temperature range: -40°C to 105°C
- EFT 4.4KV
- ESD HBM 7KV
- 1T 8051-based core running up to 7.3728MHz
- 16KB Flash; 1KB SRAM; Up to 4 KB Flash for user program loader (LDROM); ISP/ICP/IAP programming; 128 Bytes SPROM
- Internal 7.3728 MHz MIRC oscillator with variation ±10% within all temperature range; Internal 38.4kHz LIRC for low-power operating mode
Mainstream, Small, And Yes, Ultra-Low Power
The Kinetis KL1x is a general-purpose ultra-low-power MCU family, providing additional memory, communications and analog peripheral options beyond those offered in the Kinetis KL0x MCU family. The KL1x MCU family is compatible with Kinetis K10 MCUs (based on Arm Cortex-M4) and with all other Kinetis KL1x, KL2x, KL3x and KL4x series MCUs, providing a migration path to higher performance and feature integration.
- 32-bit Arm Cortex-M0+ core
- Single-cycle fast I/O access port facilitates bit banging and software protocol emulation, keeping an 8-bit “look and feel”
- Multiple flexible low-power modes, including new compute clocking option which reduces dynamic power by placing peripherals in an asynchronous stop mode
- LPUART, SPI, I2C, FlexIO, ADC, DAC, LP timer and DMA support low-power mode operation without waking up the core
- Up to 256KB flash with 64-byte flash cache, up to 32KB RAM
- Security circuitry to prevent unauthorized access to RAM and flash contents
- 16KB ROM and built-in boot loader simplifies the effort to program MCU and allows for easy flash upgrades
BLE Wireless MCU for Industrial/Medical Smart Devices
RSL15 is an ultra-low power secure Arm Cortex-M33 processor-based Bluetooth Low Energy 5.2 wireless MCU designed for connected smart devices in industrial and medical applications. The comprehensive, yet easy-to-use Software Development Kit (SDK) provides sample applications that demonstrate the hardware capabilities to enable security with the Cybersecurity Platform, acquire sensor data in Smart Sense mode, configure the built-in power management, and utilize Bluetooth Low Energy features.
- Bluetooth Low Energy 5.2 Certified with Key Features: Up to 10 simultaneous connections; Long Range (Coded PHY) 2Mbit PHY (High Speed); Extended Advertising; Backwards compatibility and support for earlier Bluetooth Low Energy specifications
- Ultra-low Power Operation: Sleep Mode (GPIO Wakeup) @ 3V VBAT: 36nA; Sleep Mode (Crystal Oscillator, RTC Timer Wakeup) @ 3V VBAT: 57nA Smart Sense Mode allows some digital and analog peripherals to remain active to monitor and acquire data from external sensors at a very low system-level power consumption; Continuous ADC operation in Smart Sense Mode with wakeup on ADC threshold @ 3V VBAT: 206nA
A General Purpose Ultra-Low Power MCU
The RA2L1 group is based on the Arm Cortex-M23 core, the most energy-efficient CPU among Arm Cortex-M today. The optimized processing and Renesas’ low power process technology makes it the industry’s most energy-efficient ultra-low power microcontroller. The RA2L1 group supports a wide operating voltage range of 1.6V to 5.5V, and a maximum CPU clock frequency of 48MHz, lower active mode current and standby mode current. The RA2L1 group also features an enhanced Capacitive Touch Sensing Unit (CTSU2), a set of serial communication interfaces, highly accurate converters and timers. The products are available with pin counts ranging from 48-pin to 100-pin.
- 48MHz Arm Cortex-M23
- 128kB/256kB Flash Memory and 32kB SRAM with ECC
- 8kB Data Flash to store data as in EEPROM
- Scalable from 48-pin to 100-pin packages
- Internal voltage regulators
- Enhanced Capacitive Touch Sensing Unit (CTSU2)
- 12-bit ADC, 12-bit DAC, LPACMP
Software-Compatible 32-Bit MCU
The EFM32PG28 32-bit microcontroller (MCU) family is a software-compatible MCU-only version of the EFR32xG28 wireless SoC platform (ZG28, FG28 and SG28). PG28 32-bit MCUs are ideal for enabling a wide range of low-power and high-performance embedded IoT applications. The highly efficient PG28 offers an 80 MHz ARM Cortex-M33, LCD controller, rich analog and communication peripherals, and more GPIOs to address complex systems. The PG28 is also the first EFM32 device with a hardware AI/ML accelerator allowing for faster inferencing at the edge with lower power consumption
- Low Power System-on-Chip
- High Performance 32-bit 80MHz ARM Cortex-M33 with DSP instruction and floating-point unit for efficient signal processing
- Up to 1024kB flash program memory
- Up to 256kB RAM data memory
- Low Energy Consumption
- 26μA/MHz in Active Mode (EM0) at 80MHz
- 2.6μA EM2 DeepSleep current (256kB RAM retention and RTC running from LFXO)
- 1.1μA EM2 DeepSleep current (16kB RAM retention and RTC running from LFXO)
Ultra-Low Power Multi-Modulation Wireless MCUs
Based on Arm Cortex-M0+ core, sub-GHz radio, and wideband wake-up radio, STM32WL3x microcontrollers support multiple modulations and an IQ interface for custom modulations for even more flexibility. The STM32WL3 is a highly integrated long-range wireless solution for IoT devices offering a simplified design approach and low power consumption for extended battery life. By contributing to longer battery lives, reducing the power consumption of wireless applications, and with its use of energy harvesting, this MCU is ideal for wireless IoT devices.
- Includes ST state-of-the-art patented technology
- Ultra-low power sub-1GHz wireless system-on-chip
- Core: Arm Cortex-M0+ 32-bit, running up to 64 MHz
- Program memory: 128-Kbyte / 256-Kbyte flash memory
- Data memory: 16-Kbyte / 32-Kbyte SRAM (full retention)
- Additional storage: 1-Kbyte OTP (user data)
- Frequency bands: 413-479 MHz, 826-958 MHz
- Air data rate from 0.1 to 600 kbit/s
- Programmable TX power up to +20dBm
- RX sensitivity @ 1% BER: -132 dBm
High-Performance Analog Peripheral Integration
Texas Instruments’ MSPM0L130x Arm Cortex-M0+ MCU features integrated 2KB SRAM, a 12-bit ADC, a comparator, and an op-amp. They are part of MSP’s highly-integrated, ultra-low-power 32-bit MSPM0 MCU family that is based on the enhanced Arm Cortex-M0+ core platform and operates at a frequency of up to 32MHz. These cost-optimized MCUs offer high-performance analog peripheral integration, support an extended temperature range of -40°C to +125°C, and operating supply voltages ranging from 1.62V to 3.6V.
- Flash: up to 64KB
- SRAM: up to 4KB
- One analog-to-digital converter (ADC): 12-bit 1.68Msps with up to ten total external channels
- Configurable internal ADC voltage reference (VREF): 1.4V or 2.5V
- Two zero-drift/crossover chopper op amps (OPA)
- One general-purpose amp (GPAMP)
- One high-speed comparator (COMP) with an 8-bit reference DAC
- Programmable analog connections between the ADC, OPAs, COMP, and the DAC
- Integrated temperature sensor
- GPIOs: up to 28 GPIOs
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • JANUARY 2024 #402 – Get a PDF of the issue
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Sam Wallace - became Circuit Cellar's Editor-In-Chief in August 2022.
His experience in writing, editing, and teaching will provide a great perspective on the selection, presentation, and clarity of editorial content. The Circuit Cellar audience will benefit from his strong academic background encompassing a Master of Fine Arts in Writing and a Bachelor of Science in Mathematics with honors. His passion for learning and teaching is a great fit for Circuit Cellar's continuing mission of Inspiring the Evolution of Embedded Design.
