Feature: Medical


per megahertz (μA/MHz) at 3.0 volts. In standby mode, it retains its state or completely powers down several blocks to achieve a power consumption of only 2.1 μA at 3.0 volts, while enabling the device to resume operation in only 14.7 microseconds (μs) (Figure 3). Along with their low-power operating


Figure 2: Running on the MAX32655’s Arm Cortex-M4 with FPU, RISC-V and radio, a full Bluetooth 5.2 stack supports a complete set of features for direction fi nding, high-throughput communication and long-range operation. (Image source: Analog Devices)


Analog Devices’ MAX32690 microcontroller offers a 120 MHz Arm Cortex-M4 with FPU along with 3 Mbytes of flash, 1 Mbyte of SRAM and 16 Kbytes of cache memory. In addition to the analog comparators and digital peripherals in the MAX32655, the MAX32690 integrates a HyperBus/ Xccela bus interface for high-speed execution from external flash and SRAM when memory requirements exceed on-chip resources. Like the MAX32655, the MAX32690 integrates a 32-bit RISC-V processor, which is available for standalone processing and Bluetooth processing support. To help developers optimise


power consumption, each of the four microcontrollers mentioned earlier supports several low-power operating modes. In the MAX32655 and MAX32690, the low power modes include: • Sleep, where the Arm Cortex-M4 with FPU (CM4) and 32-bit RISC-V (RV32) are in sleep mode, but peripherals remain on


• Low-Power Mode (LPM), where the CM4 is in sleep state with state retention while the RV32 remains active to move data from enabled


32 March 2025 www.electronicsworld.co.uk peripherals


• Micro Power Mode (UPM), where the CM4, RV32, and certain pins retain state, but a watchdog timer, analog comparators and low-power UART remain available to wake the microcontroller


• Standby, where the real-time clock remains on, and all peripherals retain state


• Backup, where the real-time clock remains on, and system memory retains its state In addition, the MAX32655 offers a


Power Down Mode (PDM) designed for use during end-product storage and distribution. In PDM mode, the MAX32655 is powered off, but an internal voltage monitor remains operational. As a result, end users can quickly power up MAX32655-based products by removing a protective battery tab or otherwise applying power to the product. These operating modes can offer


significant power savings even with ultra-low-power microcontrollers by selectively powering down different hardware blocks. For example, the MAX32655 in normal active operating mode consumes only 12.9 microamps


capabilities, these devices' high level of integration helps developers reduce design complexity and meet the requirements for a minimal footprint. For example, the MAX32655’s integrated single-inductor multiple-output (SIMO) switch-mode power supply requires only a single inductor/capacitor pair. As a result, developers can more easily create compact designs powered by a single lithium cell to meet the package requirements in applications such as asset tracking, wearables, hearables and similar space-constrained products. For a true wireless stereo (TWS) earbud design, for example, developers can implement an eff ective solution using the MAX32655 with minimal additional components beyond a codec and battery power management. Combining a MAX32655 with these devices and a DS2488 1-wire dual-port link provides a complete design for a TWS earbud and its charging cradle (Figure 4). To speed evaluation and prototyping


with these microcontrollers, developers can take advantage of multiple Analog Devices development resources, including: • MAX32655 evaluation kit (MAX32655EVKIT)


• MAX32655 feather board (MAX32655FTHR)


• MAX32690 evaluation kit (MAX32690EVKIT)


• MAX32690 Arduino form-factor development platform (AD- APARD32690-SL)


A more effective solution to mixed-signal design requirements While the MAX32655 and MAX32690 address the need for compact battery- powered Bluetooth-capable products, Analog Devices’ MAX32675C low-power


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