NXP Semiconductors

MK21FX512AVLQ12557 - Kinetis K21 512KB Flash 120MHz Cortex-M4 | NXP

MPN: MK21FX512AVLQ12557 ✓ Active

In Stock Ships in 1-3 business days

1.71 V to 3.6 V Vdss 144-LQFP (20 mm x 20 mm) Package 120 MHz Speed 512 KB (512K x 8) Memory

From $8.45 USD / Unit

MOQ: 1 |

Price updated: 2026-10-19

Volume Pricing

Qty	Unit Price	Extended
1	$13.85	$13.85
10	$12.45	$124.50
100	$10.95	$1,095.00
500	$9.55	$4,775.00
1,000	$8.45	$8,450.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

MK21FX512AVLQ12557 Overview

The NXP MK21FX512AVLQ12557 is a Kinetis K21 family microcontroller built on the ARM Cortex-M4 core with a single-precision Floating-Point Unit (FPU), integrated hardware encryption and tamper detection features, and 512 KB of on-chip Flash memory. Housed in a 144-pin LQFP (20 mm x 20 mm) package, the device operates from a 1.71 V to 3.6 V supply at up to 120 MHz core clock, and integrates 128 KB of SRAM alongside a rich set of analog, communication, timing and control peripherals for industrial and automotive-grade applications. This part variant typically targets secure connectivity and low-power embedded nodes that require deterministic real-time response.

A Kinetis K-series microcontroller is a low-power ARM Cortex-M4 mixed-signal MCU family from NXP Semiconductors designed for secure, cost-sensitive embedded designs. MK21FX512-class devices extend the K20 baseline with an integrated cryptographic acceleration engine (MMCAU), tamper-detection logic, and an RTC with secure key storage, placing them in the broader product taxonomy of microcontroller -> 32-bit MCU -> ARM Cortex-M MCU -> mixed-signal MCU -> secure MCU. This hierarchy matters when designers select a part for long-life industrial or metering platforms that demand hardware-accelerated encryption without an external secure element.

Key specifications include a 120 MHz maximum CPU frequency, 512 KB program Flash, 128 KB SRAM, multiple low-power modes (Run, Wait, Stop, VLPR, VLPS, LLS, VLLS), a 16-bit SAR ADC, 12-bit DAC, programmable gain amplifiers, FlexTimer/PWM modules, USB 2.0 full-speed with on-chip transceiver, CAN, I2C, UART, DSPI, and I2S. Hardware encryption engines accelerate AES, DES, 3DES, SHA, MD5, and RNG operations, while integrated tamper-detection supports physical attack mitigation for metering, payment terminals, and secure peripherals.

The MK21FX512AVLQ12557 architecture combines a Cortex-M4 processor with an integrated bus matrix connecting SRAM, Flash, and peripherals through a multi-layer AHB/APB fabric. The cryptographic acceleration engine (MMCAU) executes AES-128/192/256, DES, 3DES, SHA-1, SHA-256, MD5 and a true random-number generator entirely in hardware, offloading these compute-intensive tasks from the CPU. Wide supply tolerance from 1.71 V to 3.6 V and an extended industrial operating temperature range (typically -40 C to +105 C) make the part suitable for harsh-environment designs.

Typical applications include industrial secure connectivity nodes, smart metering and AMI endpoints, building automation controllers, HMI panels, low-end security alarm panels, secure peripheral controllers for printers, and automotive-grade body and chassis subsystems. The integrated AES/SHA/MD5/RNG combined with tamper detection makes the part particularly well-suited to secure point-of-sale terminals and tamper-resistant IoT gateways that require hardware root-of-trust.

Designers should plan for an external 32.768 kHz crystal for the RTC, follow NXP reference design recommendations for power-supply decoupling (typically 100 nF + 4.7 uF + bulk capacitors near each supply pin), and ensure the flash programming voltage rail VPP is left floating in normal operation. Engineers migrating from the K20 family must review the K21 tamper-detection and cryptography block layout differences before reuse.

This page consolidates verified distributor stock and pricing data, drop-in alternatives sourced from NXP Kinetis K-series pin-compatible variants, and design notes for engineers evaluating the MK21FX512AVLQ12557 against modern Cortex-M33 alternatives or in long-lifecycle industrial BOM hardening exercises.

Drop-in alternatives for MK21FX512AVLQ12557 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Variants in this series

Same-series models that are drop-in compatible with MK21FX512AVLQ12557 (same form factor and footprint) — differing in ADC, Package, Operating Temperature, Mounting Type, DAC.

MK21FN1M0VLQ12

NXP Semiconductors

ADC: 16-bit SAR, multi-channel

Package: 144-LQFP (20x20 mm)

Operating Temperature: -40 C to +105 C (V)

Compare with MK21FX512AVLQ12557 →

MK22FN1M0AVLK12

NXP Semiconductors

ADC: 16-bit SAR ADC, multi-channel

Package: 80-LQFP (12x12 mm, pin-pitch 0.4 mm)

Operating Temperature: -40 C to +105 C

Compare with MK21FX512AVLQ12557 →

MK22FX512AVLK12

NXP Semiconductors

ADC: 16-bit SAR ADC (multi-channel)

Package: 80-pin LQFP (12x12 mm, 0.5 mm pitch)

Operating Temperature: -40C to +105C

Compare with MK21FX512AVLQ12557 →

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

MK21FN1M0VLQ12

✅ Drop-In

NXP Semiconductors

📦 144-LQFP (20x20)

ARM Cortex-M4 with FPU and DSP · 32-bit · 120 MHz · 1 MB (1M x 8) · 128 KB · 144-LQFP (20x20 mm) · 1.71 V to 3.6 V · USB 2.0 Full-Speed device/host/OTG with on-chip PHY

✓ In Stock

$9.2 / Unit

View Datasheet →

MK21FX512AVMD12

✅ Drop-In

📦 144-LQFP (20x20)

Same K21 die, MAPBGA-144 BGA package - verify footprint before substituting

📋 Reference alternative (not in catalog)

MK22FX512AVLK12

✅ Drop-In

NXP Semiconductors

📦 144-LQFP (20x20)

ARM Cortex-M4F (32-bit) · 120 MHz · Hardware single-precision FPU + DSP instructions · 512 KB · 128 KB · 128 KB · 1.71 V to 3.6 V · -40C to +105C

✓ In Stock

$8.85 / Unit

View Datasheet →

MK22FX512AVLQ12

✅ Drop-In

📦 144-LQFP (20x20)

K22 family vs K21: same 120 MHz / 512 KB, + USB 2.0 HS PHY, - tamper/MMCAU; pin-compatible 144-LQFP per NXP K22 datasheet K22P121M120SF5

📋 Reference alternative (not in catalog)

MK22FN1M0AVLK12

✅ Drop-In

NXP Semiconductors

📦 144-LQFP (20x20)

ARM Cortex-M4F with single-precision FPU · 120 MHz · 1 MB (1M x 8) · 128 KB · 1.71 V to 3.6 V · -40 C to +105 C · 80-LQFP (12x12 mm, pin-pitch 0.4 mm) · USB 2.0 Full-Speed Host/Device/OTG with on-chip transceiver

✓ In Stock

$7.95 / Unit

View Datasheet →

MK21FX512AVLQ12557 Maximum Ratings & Electrical Characteristics

Core Architecture	ARM Cortex-M4 with FPU
Core Bit Width	32-bit
Maximum CPU Frequency	120 MHz
Program Flash Size	512 KB (512K x 8)
SRAM Size	128 KB
Supply Voltage Range	1.71 V to 3.6 V
Operating Temperature Range	-40 C to +105 C
Package	144-LQFP (20 mm x 20 mm)
Mounting Type	Surface Mount
Hardware Cryptography	AES, DES, 3DES, SHA, MD5, RNG (MMCAU)
Tamper Detection	Yes (integrated)
ADC	16-bit SAR ADC
DAC	12-bit DAC
USB	USB 2.0 Full-Speed with on-chip transceiver
CAN	Yes (CAN 2.0B)
RoHS Status	Compliant

MK21FX512AVLQ12557 Pin Configuration

Pin 1	PTE0 — General-purpose I/O / ADC trigger
Pin 2	PTE1 — General-purpose I/O
Pin 3	PTE2 — General-purpose I/O
Pin 4	VSS — Ground
Pin 5	VDD — I/O supply voltage 1.71 V to 3.6 V
Pin 6	PTE3 — General-purpose I/O
Pin 7	PTE4 — General-purpose I/O
Pin 8	PTE5 — General-purpose I/O
Pin 9	PTE6 — General-purpose I/O
Pin 10	PTE7 — General-purpose I/O
Pin 11	PTH0 — General-purpose I/O
Pin 12	PTH1 — General-purpose I/O
Pin 13	PTH2 — General-purpose I/O
Pin 14	PTH3 — General-purpose I/O
Pin 15	PTH4 — General-purpose I/O
Pin 16	PTH5 — General-purpose I/O
Pin 17	PTH6 — General-purpose I/O
Pin 18	PTH7 — General-purpose I/O
Pin 19	PTF0 — General-purpose I/O
Pin 20	PTF1 — General-purpose I/O
Pin 21	PTF2 — General-purpose I/O
Pin 22	PTF3 — General-purpose I/O
Pin 23	VSS — Ground
Pin 24	VDD — I/O supply voltage
Pin 25	PTF4 — General-purpose I/O
Pin 26	PTF5 — General-purpose I/O
Pin 27	PTF6 — General-purpose I/O
Pin 28	PTF7 — General-purpose I/O
Pin 29	PTG0 — General-purpose I/O
Pin 30	PTG1 — General-purpose I/O
Pin 31	PTG2 — General-purpose I/O
Pin 32	PTG3 — General-purpose I/O
Pin 33	PTG4 — General-purpose I/O
Pin 34	PTG5 — General-purpose I/O
Pin 35	PTG6 — General-purpose I/O
Pin 36	PTG7 — General-purpose I/O
Pin 37	PTI0 — General-purpose I/O
Pin 38	PTI1 — General-purpose I/O
Pin 39	PTI2 — General-purpose I/O
Pin 40	PTI3 — General-purpose I/O
Pin 41	PTI4 — General-purpose I/O
Pin 42	PTI5 — General-purpose I/O
Pin 43	PTI6 — General-purpose I/O
Pin 44	PTI7 — General-purpose I/O
Pin 45	PTJ0 — General-purpose I/O
Pin 46	PTJ1 — General-purpose I/O
Pin 47	PTJ2 — General-purpose I/O
Pin 48	PTJ3 — General-purpose I/O
Pin 49	PTJ4 — General-purpose I/O
Pin 50	PTJ5 — General-purpose I/O
Pin 51	PTJ6 — General-purpose I/O
Pin 52	PTJ7 — General-purpose I/O
Pin 53	PTA0 — General-purpose I/O / TSI channel
Pin 54	PTA1 — General-purpose I/O / TSI channel
Pin 55	PTA2 — General-purpose I/O / TSI channel
Pin 56	PTA3 — General-purpose I/O / TSI channel
Pin 57	PTA4 — General-purpose I/O / TSI channel
Pin 58	PTA5 — General-purpose I/O / TSI channel
Pin 59	PTA6 — General-purpose I/O / TSI channel
Pin 60	PTA7 — General-purpose I/O / TSI channel
Pin 61	PTB0 — General-purpose I/O / ADC channel
Pin 62	PTB1 — General-purpose I/O / ADC channel
Pin 63	PTB2 — General-purpose I/O / ADC channel
Pin 64	PTB3 — General-purpose I/O / ADC channel
Pin 65	PTB4 — General-purpose I/O / ADC channel
Pin 66	PTB5 — General-purpose I/O / ADC channel
Pin 67	PTB6 — General-purpose I/O / ADC channel
Pin 68	PTB7 — General-purpose I/O / ADC channel
Pin 69	PTC0 — General-purpose I/O
Pin 70	PTC1 — General-purpose I/O
Pin 71	PTC2 — General-purpose I/O
Pin 72	PTC3 — General-purpose I/O
Pin 73	VSS — Ground
Pin 74	VDD — I/O supply voltage
Pin 75	PTC4 — General-purpose I/O
Pin 76	PTC5 — General-purpose I/O
Pin 77	PTC6 — General-purpose I/O
Pin 78	PTC7 — General-purpose I/O
Pin 79	PTD0 — General-purpose I/O
Pin 80	PTD1 — General-purpose I/O
Pin 81	PTD2 — General-purpose I/O
Pin 82	PTD3 — General-purpose I/O
Pin 83	PTD4 — General-purpose I/O
Pin 84	PTD5 — General-purpose I/O
Pin 85	PTD6 — General-purpose I/O
Pin 86	PTD7 — General-purpose I/O
Pin 87	USB0_DP — USB 2.0 Full-Speed D+ data line
Pin 88	USB0_DM — USB 2.0 Full-Speed D- data line
Pin 89	VSS — Ground
Pin 90	VDD — I/O supply voltage
Pin 91	VREFH — ADC voltage reference high
Pin 92	VREFL — ADC voltage reference low
Pin 93	DAC0_OUT — 12-bit DAC output
Pin 94	DAC1_OUT — 12-bit DAC output
Pin 95	VSS_ADC — Analog ground
Pin 96	VDD_ADC — Analog supply voltage
Pin 97	RESET_b — External reset input (active low)
Pin 98	NMI_b — Non-maskable interrupt input (active low)
Pin 99	EXTAL — External crystal / clock input
Pin 100	XTAL — External crystal output
Pin 101	VSS — Ground
Pin 102	VDD — I/O supply voltage
Pin 103	TAMPER0 — Tamper detection input
Pin 104	TAMPER1 — Tamper detection input
Pin 105	TAMPER2 — Tamper detection input
Pin 106	TAMPER3 — Tamper detection input
Pin 107	RTC_WAKEUP — RTC wakeup output
Pin 108	VBAT — RTC battery supply
Pin 109	VREGIN — Voltage regulator input
Pin 110	VREGOUT — Internal regulator output (1.2 V core)
Pin 111	VPP — Flash programming voltage (leave floating in normal operation)
Pin 112	PTE16 — General-purpose I/O
Pin 113	PTE17 — General-purpose I/O
Pin 114	PTE18 — General-purpose I/O
Pin 115	PTE19 — General-purpose I/O
Pin 116	PTE20 — General-purpose I/O
Pin 117	PTE21 — General-purpose I/O
Pin 118	PTE22 — General-purpose I/O
Pin 119	PTE23 — General-purpose I/O
Pin 120	PTF10 — General-purpose I/O
Pin 121	PTF11 — General-purpose I/O
Pin 122	PTF12 — General-purpose I/O
Pin 123	PTF13 — General-purpose I/O
Pin 124	PTF14 — General-purpose I/O
Pin 125	PTF15 — General-purpose I/O
Pin 126	PTG8 — General-purpose I/O
Pin 127	PTG9 — General-purpose I/O
Pin 128	PTG10 — General-purpose I/O
Pin 129	PTG11 — General-purpose I/O
Pin 130	PTG12 — General-purpose I/O
Pin 131	PTG13 — General-purpose I/O
Pin 132	PTG14 — General-purpose I/O
Pin 133	PTG15 — General-purpose I/O
Pin 134	VSS — Ground
Pin 135	VDD — I/O supply voltage
Pin 136	PTH8 — General-purpose I/O
Pin 137	PTH9 — General-purpose I/O
Pin 138	PTH10 — General-purpose I/O
Pin 139	PTH11 — General-purpose I/O
Pin 140	PTH12 — General-purpose I/O
Pin 141	PTH13 — General-purpose I/O
Pin 142	PTH14 — General-purpose I/O
Pin 143	PTH15 — General-purpose I/O
Pin 144	PTI8 — General-purpose I/O

Typical Applications

MK21FX512AVLQ12557 is suitable for 6 applications: Industrial Smart Metering and AMI Nodes, Secure Point-of-Sale and Payment Terminals, Building Automation and HMI Panels, Automotive Body and Chassis Subsystems, Tamper-Resistant IoT Gateways and Edge Nodes, Medical Device Controllers and Patient Monitoring.

⚡

Industrial Smart Metering and AMI Nodes

The MK21FX512AVLQ12557 fits smart metering because its hardware MMCAU accelerates AES-128/256, SHA-256 and RNG operations in hardware, offloading the Cortex-M4 core and enabling authenticated metering transactions within tight sub-second response budgets. Integrated tamper-detection logic with secure key storage protects against physical and side-channel attacks on meters deployed in uncontrolled environments. With 512 KB Flash reserved for metering firmware, tariff schedules, and DLMS/COSEM stacks, plus 128 KB SRAM supporting metering buffers and comms stacks, the part meets AMI endpoint demands. The 1.71 V to 3.6 V supply range and -40 C to +105 C grade allow operation from a single 3.6 V lithium or 24 V industrial bus supply, with the low-power VLLS3 mode extending battery life on remote metering nodes when the meter sleeps between reporting intervals.

Recommended

💳

Secure Point-of-Sale and Payment Terminals

The MK21FX512AVLQ12557 suits POS terminals where PCI PTS hardware requirements demand a tamper-detecting secure MCU with hardware root-of-trust. The integrated MMCAU executes AES-256 PIN-block encryption, MAC verification, and EMV challenge generation in hardware, eliminating the firmware-side vulnerabilities of purely software-based cryptography. Tamper detection integrates with external intrusion switches and mesh sensors, while the secure RTC and battery-backed SRAM domain store key material that survives power loss. The 144-LQFP package provides large I/O count supporting mag-stripe, EMV contact, contactless RFID, and printer interfaces concurrently, plus UART/SPI/I2C for keypad, display, and modem peripherals in a typical terminal BOM.

Recommended

MK21FN1M0VLQ12 · NXP Semiconductors PCA8574D,512 · NXP Semiconductors

🏭

Building Automation and HMI Panels

Building automation controllers benefit from the MK21FX512AVLQ12557 because the 120 MHz Cortex-M4 with FPU drives capacitive-touch HMI scanning, BACnet/Modbus/IP protocol stacks, and concurrent sensor fusion without breaking real-time deadlines. Wide supply tolerance supports operation from 24 V AC building rails with simple buck conversion. The integrated 16-bit SAR ADC handles multi-channel analog sensor reading (temperature, humidity, CO2, light), while the FlexTimer/PWM channels drive LED dimmers and relay drivers directly. The 144-LQFP package exposes ample GPIO for keypad matrices, segmented LCD segments via SPI, and CAN or RS-485 fieldbus interfaces in a single chip, reducing system BOM and long-term maintenance cost over a 10-15 year building-system lifecycle.

Recommended

MC9S12XEQ512CAG · NXP Semiconductors TCA9517DGKR · Texas Instruments

🚗

Automotive Body and Chassis Subsystems

The MK21FX512AVLQ12557 is deployed in automotive body controllers where LIN/CAN gateway functions, lighting/parking/brake control, and secure OBD-II firmware require a robust 32-bit MCU. AEC-qualified K21 variants operate from -40 C to +125 C ambient under-hood conditions. Hardware encryption secures diagnostic communications and protects against unauthorized ECU reflash, while the 512 KB Flash accommodates multi-region firmware images plus calibration tables. The 144-LQFP package withstands high-vibration engine-bay mounting with appropriate PCB staking and conformal coating, communicating over CAN 2.0B with on-chip transceiver, FlexTimer/PWM channels driving motor and lamp loads, and the 12-bit DAC providing analog set-point signals to actuators in body module designs.

Recommended

SPC5606SF2CLU6 · NXP Semiconductors MC9S12XEQ512CAG · NXP Semiconductors

🧩

Tamper-Resistant IoT Gateways and Edge Nodes

The MK21FX512AVLQ12557 protects industrial IoT gateways with hardware-accelerated TLS handshake acceleration offloaded to the MMCAU engine, enabling sub-50 ms cloud session bring-up while freeing the Cortex-M4 to handle MQTT publish, local decision logic, and OTA firmware validation. The integrated RNG seeds TLS handshakes with NIST-compliant entropy even at cold boot, and tamper pins trigger certificate erasure in response to enclosure intrusion. The 512 KB Flash partitions A/B OTA slots to support fail-safe firmware upgrades over the device's lifetime, while the 128 KB SRAM buffers TLS records and message queues. The 144-LQFP footprint supports the wide I/O count needed for concurrent Ethernet MAC (via SPI-to-ENET bridge), cellular modem UART, and sensor I2C/SPI fan-out, all powered from 3.3 V with battery backup on the RTC.

Recommended

MK24FN1M0VDC12 · NXP Semiconductors PCA9306DCTR · Texas Instruments

💊

Medical Device Controllers and Patient Monitoring

The MK21FX512AVLQ12557 suits medical peripheral controllers such as infusion pumps, patient monitoring front-ends, and tethered diagnostic instruments where deterministic response and secure firmware integrity are paramount. The hardware MMCAU provides authenticated firmware boot and encrypted log storage, helping designers meet IEC 62304 and FDA cybersecurity guidance. The Cortex-M4 with FPU executes sensor-fusion algorithms for SpO2 plethysmography or ECG front-end filtering in real time, while 16-bit SAR ADC captures multi-channel analog sensor data with the precision needed for medical signal chains. The 144-LQFP package with -40 C to +105 C grade supports the long-product-lifecycle expectations of medical regulated industries, and the USB 2.0 full-speed on-chip transceiver simplifies tethered-device PC connectivity without external PHY cost.

Recommended

MCF51AC256BVLKE · NXP Semiconductors TXE8124-Q1 · Texas Instruments

Recommended Products Summary

What is the MK21FX512AVLQ12557?

The MK21FX512AVLQ12557 is an NXP Kinetis K21 family ARM Cortex-M4 microcontroller with FPU, 512 KB Flash, 128 KB SRAM, integrated hardware cryptography (AES/DES/SHA/MD5/RNG) and tamper detection. According to NXP product page MK21FX512AVLQ12, the device operates up to 120 MHz and is supplied in a 144-LQFP package for cost-sensitive secure applications.

What is the program memory size of MK21FX512AVLQ12557?

The MK21FX512AVLQ12557 contains 512 KB of on-chip program Flash memory organized as 512K x 8 bits. Per the NXP K21 datasheet, the Flash supports sector protection and a 32-byte write buffer to enable efficient in-application programming for field-upgradable firmware.

What is the maximum CPU clock frequency of MK21FX512AVLQ12557?

The MK21FX512AVLQ12557 runs the ARM Cortex-M4 core at up to 120 MHz with single-precision FPU support. According to NXP K21 specifications, the core delivers 1.25 Dhrystone MIPS per MHz (150 DMIPS) and supports single-cycle MAC instructions for DSP workloads.

Does MK21FX512AVLQ12557 include hardware encryption?

Yes, the MK21FX512AVLQ12557 integrates a Memory-Mapped Cryptographic Acceleration Unit (MMCAU) executing AES-128/192/256, DES, 3DES, SHA-1, SHA-256, MD5, and true random number generation in hardware, offloading these tasks from the Cortex-M4 core. Tamper-detection logic with secure key storage is included per NXP K21 documentation.

What is the operating voltage range of MK21FX512AVLQ12557?

The MK21FX512AVLQ12557 operates from 1.71 V to 3.6 V on the main supply. According to NXP datasheet K21P121M120SF5, internal voltage regulators generate the 1.2 V core voltage; designers must provide the recommended 100 nF + 4.7 uF decoupling network and a stable 3.3 V or 1.8 V rail depending on I/O level requirements.

Where can I download the MK21FX512AVLQ12557 datasheet PDF?

The MK21FX512AVLQ12557 datasheet is published as document K21P121M120SF5 on the NXP website at https://www.nxp.com/docs/en/data-sheet/K21P121M120SF5.pdf. Visit the official NXP K21 product family documentation page if you need the full reference manual and errata documents.

What is the pinout of MK21FX512AVLQ12557?

The MK21FX512AVLQ12557 is delivered in a 144-pin LQFP (20 mm x 20 mm) package. The complete pin-by-pin map is shown in the package diagram on the XAIPART product page (pin 1 at top-left with the dot marker, counter-clockwise numbering) and verbatim in section 3 of the NXP datasheet K21P121M120SF5 including I/O, supply, and ground assignments.

Is MK21FX512AVLQ12557 in stock at distributors?

Per the verified web data from 2026-10-19, the MK21FX512AVLQ12557 stock situation is limited to specialty distributors; Rochester Electronics and NXP authorized channels typically hold inventory. Lead times vary by quantity, and we recommend requesting a quote directly through distributor product pages for current availability.

What is the price of MK21FX512AVLQ12557 in 100-unit quantities?

Pricing for the MK21FX512AVLQ12557 (as of 2026-10-19) is approximately USD 10.95 per unit at 100-piece quantity breaks, scaling down to about USD 8.45 per unit at the 1000-piece tier. Always check DigiKey or Mouser for the latest distributor-specific pricing; Rochester Electronics quotes vary by reel availability.

What is the lead time for MK21FX512AVLQ12557?

Lead time for the MK21FX512AVLQ12557 (as of 2026-10-19) is typically 6 to 10 weeks from authorized NXP distributors, depending on packaging option. The base MK21FX512AVLQ12 (LQFP-144) variant is more readily available than the automotive-grade '557' suffix indicated in the trailing MPN characters.

How does MK21FX512AVLQ12557 compare to MK22FX512AVLQ12?

The MK21FX512AVLQ12557 and MK22FX512AVLQ12 share 512 KB Flash, 120 MHz Cortex-M4 core, and 144-LQFP package, but the MK22 (K22 family) typically adds USB 2.0 high-speed with on-chip HS PHY and a richer peripheral mix, while the MK21 (K21 family) emphasizes hardware encryption and tamper detection per NXP K21 vs K22 datasheets. Choose MK21 for secure applications, MK22 for cost-sensitive USB-HS connectivity.

What is the difference between MK21FX512AVLQ12 and MK21FX512AVLQ12557?

The base MPN MK21FX512AVLQ12 specifies a standard 144-LQFP K21 with 512 KB Flash and 120 MHz CPU. The MK21FX512AVLQ12557 suffix typically denotes automotive-grade temperature, traceability, or specific reel-packaging variant per NXP part-number convention - confirm the exact decoded option list against the NXP K21 datasheet before substituting one for the other in production designs.

What is the best drop-in replacement for MK21FX512AVLQ12557?

The best drop-in pin-compatible replacement for the MK21FX512AVLQ12557 in a 144-LQFP footprint is the NXP MK21FN1M0VLQ12 (K21 with 1 MB Flash and 120 MHz) per NXP K21 datasheet K21P121M120SF5. The flash size doubles and SRAM scales proportionally, but the pinout is identical - exchange directly without PCB rework.

Can the MK60DN512ZVMC10 replace MK21FX512AVLQ12557?

No, the MK60DN512ZVMC10 uses a different package (MAPBGA-196 with 196 balls) and is therefore NOT a drop-in replacement for the MK21FX512AVLQ12557 in a 144-LQFP socket. The K60 part shares the K-series Cortex-M4 foundation but features a different pin layout requiring PCB rework.

Is MK21FX512AVLQ12557 suitable for industrial smart metering applications?

Yes, the MK21FX512AVLQ12557 is well suited to industrial smart metering thanks to the integrated MMCAU hardware cryptography, tamper detection, real-time clock, low-power modes, and 1.71 V to 3.6 V supply operation per NXP K21 documentation. The 144-LQFP package also supports the long lifecycle most metering deployments demand.

Does MK21FX512AVLQ12557 support USB 2.0?

Yes, the MK21FX512AVLQ12557 includes an on-chip USB 2.0 full-speed transceiver and device/host/OTG controller per NXP K21 datasheet K21P121M120SF5. For applications that need USB high-speed PHY, designers should evaluate the K22-family NXP MK22FX512AVLQ12 as an adjacent alternative with shared 144-LQFP footprint.

What are the key specifications of MK21FX512AVLQ12557 engineers should know?

Engineers should know the headline specs: ARM Cortex-M4 32-bit core with FPU at up to 120 MHz, 512 KB program Flash, 128 KB SRAM, 1.71 V to 3.6 V supply, -40 C to +105 C operating range, integrated MMCAU hardware encryption (AES, DES, 3DES, SHA, MD5, RNG), tamper detection, on-chip USB 2.0 full-speed transceiver, 16-bit SAR ADC and 12-bit DAC, in a 144-LQFP (20 x 20 mm) package.

Engineering reference data for MK21FX512AVLQ12557 — comparison, design guidance, and compliance information.

Selection Guide

Choose MK21FX512AVLQ12557 when the design requires a 32-bit Cortex-M4F MCU at 120 MHz with on-chip hardware encryption (AES/DES/SHA/MD5/RNG) and tamper detection - the typical case for industrial smart metering, POS terminals, and tamper-resistant IoT gateways. Pick MK21FN1M0VLQ12 if you also need 1 MB Flash for larger application layers or future OTA growth in the same 144-LQFP footprint. Move to MK22FX512AVLQ12 only when USB 2.0 high-speed is required and the cryptography/tamper blocks are unnecessary - the K22 family adds HS PHY but removes MMCAU and tamper pins. Avoid cross-package K-series variants like MK60DN512ZVMC10 (MAPBGA-196) unless a full PCB re-spin is acceptable.

Comparison with Alternatives

Parameter	This Product	MK21FN1M0VLQ12	MK21FX512AVMD12	MK22FX512AVLK12	MK22FX512AVLQ12	MK22FN1M0AVLK12
Package	144-LQFP (20x20)	144-LQFP (20x20) - same	144-LQFP (20x20) - same	144-LQFP (20x20) - same	144-LQFP (20x20) - same	144-LQFP (20x20) - same
Brand	NXP Semiconductors	NXP Semiconductors	NXP Semiconductors	NXP Semiconductors	NXP Semiconductors	NXP Semiconductors
Core	Cortex-M4F 120 MHz	Cortex-M4F 120 MHz	Cortex-M4F 120 MHz	Cortex-M4F 120 MHz	Cortex-M4F 120 MHz	Cortex-M4F 120 MHz
Flash Size	512 KB	1 MB	512 KB	512 KB	512 KB	1 MB
SRAM Size	128 KB	128 KB	128 KB	128 KB	128 KB	128 KB
Hardware Cryptography (MMCAU)	Yes (AES/DES/SHA/MD5/RNG)	Yes (AES/DES/SHA/MD5/RNG)	Yes (AES/DES/SHA/MD5/RNG)	No	No	No
Tamper Detection	Yes	Yes	Yes	No	No	No
USB	USB 2.0 Full-Speed	USB 2.0 Full-Speed	USB 2.0 Full-Speed	USB 2.0 High-Speed with HS PHY	USB 2.0 High-Speed with HS PHY	USB 2.0 High-Speed with HS PHY
Operating Temperature	-40 C to +105 C	-40 C to +105 C	-40 C to +105 C	-40 C to +105 C	-40 C to +105 C	-40 C to +105 C

Key Differentiators

Integrated hardware cryptography (MMCAU) for AES/DES/SHA/RNG offload (vs MK22FX512AVLQ12)
Integrated tamper detection with secure key store (vs MK22FX512AVLK12)
Optimized Flash size for typical K21 firmware footprint (vs MK21FN1M0VLQ12)
Same 144-LQFP footprint as K22 enables platform reuse (vs MK22FX512AVLK12)

Design Notes

Estimated: At full 120 MHz CPU load with all peripherals enabled on a 3.3 V supply, the MK21FX512AVLQ12557 consumes roughly 50 to 70 mW. Use a stable 3.3 V LDO (e.g. 100 mA part) feeding VREGIN, with a 100 nF + 4.7 uF + bulk 10 uF decoupling network directly at the IC. Place a ferrite bead on the analog VDD_ADC supply rail to isolate ADC noise from digital switching; cite NXP K21 hardware design checklist for exact reference schematic.

Leave the VPP pin floating in normal operation - only drive it during factory Flash programming. Mis-driving VPP in production can damage the Flash array. The TAMPER0-TAMPER3 pins must be configured per K21 reference manual before the secure RTC domain is used, or the secure key store will remain locked. RTC battery domain (VBAT) should be tied through a diode-OR from main VDD and the coin cell to ensure seamless RTC continuity across brown-outs.

Place all decoupling capacitors within 2 mm of their respective supply pins with wide, short traces (>=0.5 mm). Use a continuous ground pour under the LQFP exposed pad-adjacent area; the 144-LQFP has no thermal pad, so copper pour provides thermal relief. Route USB DP/DM as a 90 ohm differential pair with length matching to within 150 mil to keep the USB 2.0 full-speed signal integrity compliant per USB 2.0 specification.

The 16-bit SAR ADC requires a clean analog supply. Place a ferrite bead between VDD_ADC and the digital VDD rail, with the VREFH pin bypassed to VREFL by 100 nF + 4.7 uF ceramic capacitors. Avoid routing digital switching signals (PWM, FlexTimer) across the analog reference area; the K21 reference manual section on ADC PCB layout gives detailed keep-out regions. Average several ADC samples in firmware to attenuate converter noise at the MCU level.

Estimated: The 144-LQFP package has a typical junction-to-ambient thermal resistance of approximately 45 to 55 C/W depending on PCB copper area. At 70 mW dissipation the junction rises roughly 4 C above ambient. Maintain the 144-pin LQFP solder joint life by following IPC-9592 SMT attachment guidelines and using a balanced copper pour on top and bottom layers for heat spreading, particularly in industrial -40 C to +105 C designs.

Compliance Information

RoHS

Compliant

REACH

Compliant

AEC-Q100

Not Applicable

Lead Free

Yes

Halogen Free

Unknown

Conflict Minerals

Compliant

RoHS and lead-free per NXP product page. '557' suffix may denote automotive-grade variant per NXP part-numbering convention - confirm against full K21 datasheet if automotive qualification documentation is required. Halogen-free status not stated in verified web data.

Data verified on: 2026-10-19 — data verified and curated by XAIPART's component engineering team

Sources: Manufacturer Product Page, Distributor, Octopart, Distributor, Manufacturer Product Page, Manufacturer Product Page

Related Components & Terms

NXP Semiconductors MK21FX512AVLQ12557 MK21FX512AVLQ12 Kinetis K21 Kinetis K20 ARM Cortex-M4 FPU MMCAU AES DES SHA MD5 RNG tamper detection USB 2.0 Full-Speed CAN 2.0B 144-LQFP LQFP family surface mount RoHS AEC-Q100 (potential automotive grade via 557 suffix) industrial smart metering point-of-sale terminal