NXP Semiconductors MK21DX256AVMC5R

Overview

MK21DX256AVMC5 from NXP Semiconductors (formerly Freescale) is a 50 MHz ARM® Cortex®-M4-based microcontroller with 256 KB flash, 64 KB SRAM, and DryIce tamper detection. It integrates USB LS/FS OTG 2.0 with embedded 3.3 V/120 mA LDO, 16-bit SAR ADC, and hardware AES/SHA-256 encryption-designed for secure, low-power electronic point-of-sale terminals.

For engineers reviewing the MK21DX256AVMC5 datasheet, MK21DX256AVMC5 pinout, MK21DX256AVMC5 application, or MK21DX256AVMC5 equivalent, key selection considerations include its 121-pin MAPBGA package, –40°C to 105°C industrial temperature range, 1.71–3.6 V supply, ultra-low 3.1 μA static power with full state retention, and support for USB device charger detection (USBDCD) in cost-sensitive embedded security applications.

Technical Context

The MK21DX256AVMC5 implements an ARM Cortex-M4 core with DSP extensions and a tightly coupled memory subsystem including FlexNVM/FlexRAM. Its clock system combines a 32 kHz RTC oscillator, 3–32 MHz crystal oscillator, and multipurpose clock generator supporting multiple low-power modes-including VLLS0 with 359 nA current draw and 6 μs wakeup from STOP mode.

Security architecture centers on DryIce tamper detection with active/passive pin monitoring, voltage/temperature/clock fault sensing, and hardware-accelerated cryptographic engines for DES, 3DES, AES, MD5, SHA-1, and SHA-256. Analog subsystem includes a 16-bit SAR ADC, dual comparators, 12-bit DAC, and voltage reference-all operating across the full 1.71–3.6 V supply range.

Key Specifications

Pinout & Package

Package: 121-pin MAPBGA (8 mm × 8 mm × 1.4 mm, 0.65 mm pitch). Pinout validated per Kinetis K21D Sub-Family Data Sheet Rev 6 (Document K21P121M50SF4V2).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MK21DX256AVMC5, MK21DN512AVMC5 offers direct scalability within the same footprint and security model, while MK22FN512VLH12 trades tamper protection for raw performance and interface breadth-making it unsuitable for PCI PTS or FIPS-aligned deployments despite higher clock speed.

Availability

MK21DX256AVMC5 is available at Aetrix Electronics and suitable for electronic point-of-sale terminals, secure industrial controllers, and low-power medical devices requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for MK21DX256AVMC5 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 embedded security.

The Kinetis K21D family-including MK21DX256AVMC5-is designed specifically for cost-sensitive, security-critical embedded applications such as payment terminals and industrial edge nodes, emphasizing tamper resistance, ultra-low-power operation, and USB-enabled connectivity.

FAQ

What is the maximum operating frequency of the MK21DX256AVMC5?

The MK21DX256AVMC5 operates at up to 50 MHz on its ARM Cortex-M4 core. This frequency is maintained in normal run mode with full peripheral enablement and is reduced to 4 MHz in Very-Low-Power Run (VLPR) mode to minimize dynamic power consumption while retaining full code execution capability. The core delivers 1.25 Dhrystone MIPS per MHz, enabling efficient signal processing and real-time control tasks within the MK21DX256AVMC5's power envelope.

Does the MK21DX256AVMC5 support USB device charger detection (USBDCD)?

Yes, the MK21DX256AVMC5 includes dedicated USB Device Charger Detect (USBDCD) circuitry compliant with USB Battery Charging Specification v1.2. This allows the MK21DX256AVMC5 to automatically identify downstream charging ports (SDP, CDP, DCP) without host intervention, enabling optimized battery charging profiles in portable devices. The feature operates independently of the USB OTG controller and requires no external components beyond standard USB termination resistors.

What security features does the MK21DX256AVMC5 provide for tamper-resistant applications?

The MK21DX256AVMC5 integrates Freescale's DryIce tamper detection engine, which monitors active and passive pins, supply voltage, temperature, and clock integrity in real time. Upon detecting anomalies, it triggers configurable responses including secure memory wipe, reset assertion, and interrupt generation. Combined with hardware AES/SHA-256 engines, 128-bit unique chip ID, and hardware RNG, these features meet requirements for PCI PTS v6.0 and other anti-tamper standards in the MK21DX256AVMC5's target applications.

What is the minimum supply voltage required for RAM retention in the MK21DX256AVMC5?

The MK21DX256AVMC5 retains full SRAM contents down to 1.2 V on the VDD rail, as specified in the "Voltage and current operating requirements" section of the datasheet. This enables extended operation during brown-out conditions and supports graceful shutdown sequences. Below 1.2 V, RAM retention is not guaranteed, and the device enters POR reset at 0.8–1.5 V depending on slew rate-ensuring deterministic behavior during power failure events affecting the MK21DX256AVMC5.

Is the MK21DX256AVMC5 pin-compatible with other Kinetis K21 family members?

The MK21DX256AVMC5 shares the same 121-pin MAPBGA package and pinout with MK21DX128AVMC5 and MK21DN512AVMC5, enabling direct PCB-level compatibility across flash variants. All three parts maintain identical peripheral signal assignments, power/ground pin locations, and debug interface placement-allowing firmware reuse and scalable memory selection without layout changes. However, MK21DX256AVMC5 is not pin-compatible with K22 or K6x series devices due to differing peripheral sets and package footprints.