NXP Semiconductors MK21DX256VLK5

Overview

MK21DX256VLK5 from NXP Semiconductors (formerly Freescale) is a 32-bit ARM Cortex-M4 microcontroller with DSP extension, operating at up to 50 MHz, featuring 256 KB on-chip program flash with FlexMemory, 64 KB RAM, and integrated USB OTG, ADC, timers, and cryptographic accelerators. It targets industrial control, sensor hubs, and secure IoT edge nodes requiring low-power operation across –40°C to 105°C.

For engineers reviewing the MK21DX256VLK5 datasheet, MK21DX256VLK5 pinout, MK21DX256VLK5 application, or MK21DX256VLK5 equivalent, key selection considerations include its FlexNVM configuration (256 KB flash + 64 KB FlexNVM), 80-pin LQFP package, -40°C to 105°C temperature grade, USB full/low-speed OTG support, and hardware AES/SHA-256 acceleration for secure firmware updates.

Technical Context

The MK21DX256VLK5 implements an ARM Cortex-M4 core with DSP instructions and no FPU, clocked by a multi-purpose clock generator supporting 3–32 MHz crystal and 32 kHz RTC oscillators. Its memory subsystem includes 256 KB program flash, 64 KB SRAM, and FlexMemory comprising 64 KB FlexNVM and 4 KB FlexRAM - enabling EEPROM emulation and data logging without external storage.

Peripherals include a 16-bit SAR ADC with 16 channels, two analog comparators with integrated 6-bit DACs, eight-channel PWM timer, real-time clock, carrier modulator transmitter, and four UARTs. Security is enforced via hardware CRC, tamper detection, TRNG, and cryptographic engines for DES, 3DES, AES, MD5, SHA-1, and SHA-256.

Key Specifications

Pinout & Package

Package: 80-pin LQFP (12 mm × 12 mm), RoHS-compliant, moisture sensitivity level 3 (MSL3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microcontroller applications.

Compared with MK22FN512VLH12 and STM32L476RG, the MK21DX256VLK5 uniquely balances USB OTG with on-chip transceiver, FlexMemory for robust firmware/data partitioning, and analog subsystem depth - making it the most integrated solution for industrial USB peripherals and secure sensor edge nodes where pin count, BOM simplicity, and EEPROM emulation are design constraints.

Availability

MK21DX256VLK5 is available at Aetrix Electronics and suitable for industrial motor control, secure IoT edge nodes, medical patient monitors, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MK21DX256VLK5 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT markets, with deep expertise in ARM-based microcontrollers and edge AI processing.

The Kinetis K21 family, including MK21DX256VLK5, was designed specifically for cost-sensitive, low-power industrial and consumer applications demanding robust security, analog integration, and USB connectivity - bridging the gap between legacy 8-bit MCUs and high-end application processors.

FAQ

What is the maximum operating frequency of the MK21DX256VLK5?

The MK21DX256VLK5 operates at a maximum core/system clock frequency of 50 MHz. This is specified in the K21 Sub-Family Data Sheet (Rev. 4.1) under Device Clock Specifications, where fSYS is rated at ≤50 MHz in normal run mode. The MK21DX256VLK5 achieves 1.25 Dhrystone MIPS per MHz, delivering 62.5 DMIPS total - sufficient for real-time control tasks such as motor commutation and sensor fusion without requiring higher-clock alternatives.

Does the MK21DX256VLK5 include an integrated USB transceiver?

Yes, the MK21DX256VLK5 includes a full-/low-speed USB On-The-Go controller with an integrated transceiver. As confirmed in the K21 Sub-Family Data Sheet Section 6.8.1, the USB module supports both host and device roles and eliminates the need for an external USB PHY chip. This is implemented via dedicated USB0_DP and USB0_DM pins, enabling direct connection to USB connectors in compact industrial and medical designs.

What memory configuration does the MK21DX256VLK5 provide?

The MK21DX256VLK5 features 256 KB of program flash memory, 64 KB of general-purpose SRAM, and FlexMemory consisting of 64 KB FlexNVM and 4 KB FlexRAM. Per the K21 Sub-Family Data Sheet Section 5.4.1, this FlexNVM enables EEPROM emulation with byte-level write and 100k-cycle endurance, while FlexRAM serves as fast, non-volatile data cache - a key differentiator versus standard flash-only MCUs like the MK21DN512VLK5.

What is the operating temperature range for the MK21DX256VLK5?

The MK21DX256VLK5 is rated for an ambient operating temperature range of –40°C to +105°C, as defined by the 'V' suffix in its part number per the K21 Sub-Family Data Sheet Section 2.3. This wide industrial temperature grade is validated across all electrical specifications including flash programming, ADC linearity, and USB timing - making it suitable for under-hood automotive modules, industrial PLCs, and outdoor utility metering applications.

Which security features are hardware-accelerated in the MK21DX256VLK5?

The MK21DX256VLK5 integrates dedicated hardware accelerators for CRC-32, DES/3DES, AES-128/192/256, MD5, SHA-1, and SHA-256 cryptographic operations, plus a true random number generator (TRNG) and tamper-detect circuitry. These are documented in Sections 6.5 and 6.6 of the K21 Sub-Family Data Sheet. Unlike software-only implementations, these accelerators reduce AES-256 encryption latency by >95% and enable secure boot verification in <10 ms - critical for OTA firmware updates in constrained-edge devices.