Low-Power ARM Cortex-M4 with FPU-Based Microcontroller with Bluetooth 5 for Wearables

Generation UB MCUs are Built to Run Complex Applications Demanded by Battery-Powered and Wirelessly Connected Devices

Please check latest availability status for a specific part variant.


DARWIN is a new breed of low-power microcontrollers built to thrive in the rapidly evolving Internet of Things (IoT). They are smart, with the biggest memories in their class and a massively scalable memory architecture. They run forever, thanks to wearable-grade power technology. They are durable enough to withstand the most advanced cyberattacks. DARWIN microcontrollers are designed to run any application imaginable—in places where you would not dream of sending other microcontrollers.

Generation UB microcontrollers are designed to handle the increasingly complex applications demanded by today's advanced battery-powered devices and wirelessly connected devices, while providing robust hardware security and Bluetooth® 5 Low Energy (BLE) radio connectivity.

The MAX32665–MAX32668 UB class microcontrollers are advanced systems-on-chips featuring an Arm® Cortex®-M4 with FPU CPU for efficient computation of complex functions and algorithms with integrated power management. They also include the newest generation Bluetooth 5 Low Energy radio with high throughput (2Mbps) and Maxim's best-in-class hardware security suite trust protection unit (TPU). The devices offer large on-board memory with 1MB flash and up to 560KB SRAM that can be configured as 448KB SRAM with error correction coding (ECC). Split flash banks of 512KB each support seamless over the air upgrades, adding an additional degree of reliability. Memory scalability of data (SRAM) and code (flash) space is supported by two SPI execute-in-place (SPIX) interfaces.

Multiple high-speed interfaces are supported including HS-USB, secure digital interface (SD, SDIO, MMC, SDHC, and microSD™), SPI, UART, and I2C serial interfaces, and an audio subsystem supporting PDM, PCM, I2S, and TDM interfaces. An 8-input, 10-bit ADC is available to monitor analog inputs from external sensors and meters. The devices are available in 109-bump WLP (0.35mm pitch) and 121-bump CTBGA (0.65mm pitch).

MAX32665, MAX32666, MAX32667, MAX32668: Simplified Block Diagram MAX32665, MAX32666, MAX32667, MAX32668: Simplified Block Diagram Enlarge+

Key Features

  • High-Efficiency Microcontroller and Audio DSP for Wearable and Hearable Devices
    • Arm Cortex-M4 with FPU Up to 96MHz
    • Optional Second Arm Cortex-M4 with FPU Optimized for Data Processing
    • Low-Power 7.3728MHz System Clock Option
    • 1MB Flash, Organized into Dual Banks 2 x 512KB
    • 560KB (448KB ECC) SRAM; 3 x 16KB Cache
    • Optional Error Correction Code (ECC-SEC-DED) for Cache, SRAM, and Internal Flash
  • Bluetooth 5 Low Energy Radio
    • 1Mbps and 2Mbps Data Throughput
    • Long Range (125kbps and 500kbps)
    • Advertising Extension
    • Rx Sensitivity: -95dbm; Tx Power Up to +4.5dbm
    • On-Chip Matching with Single-Ended Antenna Port
  • Power Management Maximizes Operating Time for Battery Applications
    • Integrated SIMO SMPS for Coin-Cell Operation
    • Dynamic Voltage Scaling Minimizes Active Core Power Consumption
    • 27.3µA/MHz at 3.3V Executing from Cache
    • Selectable SRAM Retention in Low Power Modes with RTC Enabled
  • Multiple Peripherals for System Control
    • Three QSPI Master/Slave with Three Chip Selects Each, Three 4-Wire UARTs, Three I2C Master/Slave, Up to 50 GPIOs
    • QSPI (SPIXF) with Real-Time Flash Decryption
    • QSPI (SPIXR) RAM Interface Provides SRAM Expansion
    • 8-Input, 10-Bit Delta-Sigma ADC 7.8ksps
    • USB 2.0 HS Engine with Internal Transceiver
    • PDM Interface Supports Two Digital Microphones
    • I2S with TDM, Six 32-Bit Timers, Two High-Speed Timers, 1-Wire Master, Sixteen Pulse Train (PWM) Engines
    • Secure Digital Interface Supports SD3.0/SDIO3.0/eMMC4.51
  • Secure Valuable IP/Data with Hardware Security
    • Trust Protection Unit (TPU) with MAA Supports Fast ECDSA and Modular Arithmetic
    • AES128/192/256, DES, 3DES, Hardware Accelerator
    • TRNG Seed Generator, SHA-2 Accelerator
    • Secure Bootloader


  • Connected Home
  • Gaming Devices
  • Hearables
  • Industrial Sensors
  • Payment/Fitness/Medical Wearables
  • Telemedicine

See parametric specs for Microcontrollers (55)

Part NumberMCU CoreCore Clock Speed
Data ProcessingInternal Flash
Internal SRAM
UARTsSPI BusI2C BusGPIO PinsPWMTimer FeaturesPackage/PinsBudgetary
maxmaxSee Notes
MAX32666 Dual ARM Cortex-M4F9632-bit1024560333 Master, 3 Slave486
Wake Up Timer
$6.23 @1k
MAX32668 ARM Cortex-M4F192

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX32665EVKIT: Evaluation Kit for the MAX32665/MAX32666/MAX32667/MAX32668
MAX32666EVKIT: Evaluation Kit for the MAX32665/MAX32666/MAX32667/MAX32668
MAX32666FTHR: Evaluation Kit for the MAX32666
Request Reliability Report for: MAX32666 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >


Related Resources

High Reliability, Ultra-Low Power Microcontroller Powered by Arm Cortex M4 Processor with FPU for Industrial and IoT

  • High-Efficiency Microcontroller for Low Power, High Reliability Devices
  • Flexible Clocking Schemes
  • Power Management Maximizes Uptime for Battery Applications

High Reliability, Ultra-Low Power Microcontroller Powered by Arm Cortex M4 Processor with FPU for Industrial and IoT

  • High-Efficiency Microcontroller for Low Power, High Reliability Devices
  • Flexible Clocking Schemes
  • Power Management Maximizes Uptime for Battery Applications

Type ID Title
User Guide 6971 MAX32665-MAX32668 User Guide
User Guide 6245 Getting Started with Eclipse