Maxim Integrated Unveils “World’s Most Secure IoT Microcontroller”

February 28, 2020 by Gary Elinoff

The MAX32520, based on the Arm Cortex-M4 processor, features physically unclonable function (PUF) technology to enhance security.

Maxim Integrated has announced the new MAX32520 microcontroller, which integrates Maxim's ChipDNA technology and Arm's Cortex-M4 processor. Maxim claims the new device is the first MCU featuring on-board physically unclonable function (PUF) technology.

In addition, the MAX32520 includes DeepCover embedded security solutions that are said to provide advanced key-protection technology for IoT edge devices and other applications requiring the highest levels of security.


Extended Secure Serial Boot/External Code Flash with Secure System

A diagram of MAX32520's secure serial boot/external code flash. Image used courtesy of Maxim Integrated


IoT applications, in ever-increasing numbers, are being deployed in open, potentially hostile locations, where they are exposed to hardware attacks. The MAX32520 with its ChipDNA technology deploys tamper-proof PUF circuitry to generate encryption keys that aim to withstand even those threats.


What Is ChipDNA PUF?

Maxim Integrated explains that its ChipDNA PUF technology enables protection against invasive physical attacks. It works by exploiting the small, random variations of semiconductor devices that inevitably occur during wafer fabrication.

Based on these tiny variations, ChipDNA circuitry generates a unique output value that doesn’t vary over temperature, time, or operating voltage. Any attempts to observe or probe ChipDNA operation modifies the underlying circuit characteristics. This prevents attackers from finding out the unique value of the cryptographic functions of the chip. 

Accordingly, the MAX32520 utilizes the ChipDNA output to cryptographically secure all of the device’s stored content, including firmware. User firmware encryption is a powerful method for the vital task of software IP protection. 


Use cases for ChipDNA PUF embedded security technology

A few use cases for ChipDNA PUF embedded security technology. Image used courtesy of Maxim Integrated

The ChipDNA can also generate a private key for the Elliptic Curve Digital Signature Algorithm (ECDSA) signing operation. Bitcoin uses this algorithm to prevent unauthorized access to funds. 

Kris Ardis, executive director of the security and software business unit at Maxim Integrated, describes, “The threats to IoT systems are getting more advanced all the time, and tools to attack systems move from the realm of academia to the realm of open source every day.”

He goes on to state that “MAX32520 with ChipDNA is a step forward. Built around the most advanced key security technology and targeting IoT applications, it will protect your data and IP, and has the technology to future-proof designs against tomorrow’s system threats.”


Key Specifications of MAX32520

The MAX32520 incorporates an Arm Cortex-M4F with FPU that can be clocked at speeds of up to 120 MHz. There are 2 MB of flash memory, 136 KB of SRAM and 34 KB of error-correcting code ECC memory. There is also 128 KB of boot ROM and 8 KB of user-programmable, one-time programmable (OTP) memory.



Simplified block diagram of the MAX32520. Image used courtesy of Maxim Integrated


The device supports SPI, UART, and an I2C interface. An SPI port supports a serial flash emulation mode for direct code fetching, enabling secure boot for a host MCU.

The MAX32520 can run on 3.3 V, 2.5 V, and 1.8 V power supplies. It draws 3.2 µA in backup mode and can wake up in 15 microseconds from standby mode.


Designed for High Security

The MAX32520 is designed for applications in which security is of paramount importance. Maxim Integrated has identified a few possible uses: 

  • IoT nodes and gateways at the edge
  • Banking and financial applications
  • Secure industrial controllers, sensors, and appliances
  • Embedded communications equipment, such as gateways and routers
  • Set-top boxes


Support Tools

The MAX32520 evaluation kit enables designers to assess the MAX32520's capabilities.



The MAX32520 evaluation kit. Image used courtesy of Maxim Integrated


The evaluation kit includes a preprogrammed demo and an A to Micro B USB cable.


Feature image (modified) used courtesy of Mouser and Maxim Integrated



Has increased emphasis on secure hardware affected your design process? Share your experiences in the comments below.