NXP Semiconductors MKM35Z256VLL7R

Overview

MKM35Z256VLL7R from NXP Semiconductors is a 32-bit Arm® Cortex®-M0+ microcontroller optimized for high-accuracy electricity metering, featuring four 24-bit ΣΔ ADCs with programmable gain amplifiers, 256 KB flash/64 KB SRAM, hardware tamper detection with timestamping, and integrated segment LCD controller - deployed in revenue-grade 1-/2-/3-phase smart meters compliant with WELMEC/OIML recommendations.

For engineers reviewing the MKM35Z256VLL7R datasheet, MKM35Z256VLL7R pinout, MKM35Z256VLL7R application, or MKM35Z256VLL7R equivalent, this device delivers metrology-grade analog front-end performance, secure cryptographic acceleration (AES/MMCAU/RNG), low-power RTC with VBAT backup, and 13 configurable power modes - critical for utility-grade meter design, firmware validation, and tamper-resilient firmware architecture.

Technical Context

The MKM35Z256VLL7R integrates a dedicated Metering-specific Memory Mapped Arithmetic Unit (MMAU) to accelerate real-time energy calculations, and its AFE subsystem supports simultaneous sampling across four independent 24-bit ΣΔ ADC channels with PGA gain up to 32×, enabling direct connection to current transformers and shunt resistors without external signal conditioning. Its iRTC includes hardware tamper detection with time stamping and operates in VBAT domain at <1 μA, preserving calibration data and event logs during main supply loss.

Core clocking uses a multi-source architecture: 75 MHz internal reference (±0.5% over voltage/temp), FLL/PLL for system clock synthesis, and dual crystal support (32.768 kHz for iRTC, 1–32 MHz for main oscillator). The memory protection unit (MPU), MMCAU crypto engine, and PCRC integrity checker enforce secure boot and runtime code/data integrity - essential for certified meter firmware deployment.

Key Specifications

Pinout & Package

Package: 100-pin LQFP (14 mm × 14 mm, 0.5 mm pitch), RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MKM35Z256VLQ7R, MKM35Z256VLL7R offers identical metrology performance in a smaller 100-LQFP package - reducing PCB area by 30% and simplifying layout. Against STM32G071KBT6, MKM35Z256VLL7R provides end-to-end metrology integration, eliminating external component risk and certification overhead for utility-grade deployments.

Availability

MKM35Z256VLL7R is available at Aetrix Electronics and suitable for revenue-grade smart meters, prepayment energy meters, and industrial power monitors requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for utility-certified designs.

Supply support for MKM35Z256VLL7R 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 specializing in secure connectivity solutions for automotive, industrial, and IoT markets, with deep expertise in metrology and embedded security.

The KM35 sub-family targets electricity meter manufacturers seeking single-chip, WELMEC/OIML-compliant solutions - integrating metrology-grade AFE, tamper resilience, and secure firmware execution in one Arm® Cortex®-M0+ platform.

FAQ

What is the maximum operating frequency of the MKM35Z256VLL7R core?

The MKM35Z256VLL7R features an Arm® Cortex®-M0+ core rated for up to 75 MHz operation under normal run mode conditions. This frequency is supported across the full temperature range (–40 to 105 °C) and voltage range (2.7–3.6 V) when the AFE is active. In very-low-power run mode (VLPR), the core operates up to 4 MHz to minimize current draw while maintaining peripheral responsiveness. The 75 MHz capability enables real-time execution of metrology algorithms using the dedicated MMAU accelerator within MKM35Z256VLL7R.

Does the MKM35Z256VLL7R include hardware support for electricity meter certification standards?

Yes, the MKM35Z256VLL7R includes multiple hardware features required for IEC 62053-21/22, OIML R46, and WELMEC 7.2 compliance: four 24-bit ΣΔ ADCs with PGA, auto-compensated iRTC with tamper timestamping, hardware CRC and PCRC engines for firmware/data integrity, and memory protection unit (MPU) for secure boot enforcement. These capabilities are documented in the KM35 Sub-Family Data Sheet Rev. 2 and validated in NXP's certified meter reference designs - confirming MKM35Z256VLL7R's suitability as the metrology engine in Class B and C revenue meters.

What are the power consumption characteristics of the MKM35Z256VLL7R in deep sleep mode?

In deep sleep (VLLS0) mode with POR detect circuit disabled, the MKM35Z256VLL7R draws as low as 261 nA at 3.0 V and 25 °C - meeting EN 50470-3 standby current limits for Class B meters. With POR enabled, typical current rises to 559 nA. These values are characterized across –40 to 105 °C and include leakage from the VBAT domain powering iRTC and tamper registers. The ultra-low current is achieved via selective clock gating, retention RAM configuration, and optimized LDO biasing - all verified in MKM35Z256VLL7R production test data.

How does the MKM35Z256VLL7R handle tamper detection and evidence logging?

The MKM35Z256VLL7R implements four dedicated hardware tamper inputs (TAMPER0–TAMPER3) that trigger immediate interrupt generation and timestamp capture in the VBAT-powered iRTC domain. Tamper events are logged to tamper memory backed by VBAT, ensuring persistence during main supply loss. The device also supports tamper source identification (e.g., case open, magnetic attack, voltage glitch) via configurable GPIO mapping and includes hardware-enforced write protection for tamper registers - a requirement explicitly addressed in WELMEC 7.2 Annex D for MKM35Z256VLL7R-based meter certifications.

Is the MKM35Z256VLL7R pin-compatible with other KM35 family members?

No, the MKM35Z256VLL7R (100-pin LQFP) is not pin-compatible with MKM35Z256VLQ7R (144-pin LQFP) due to differing pin counts and physical layout - though both share identical electrical specifications, register maps, and firmware compatibility. Pinouts for MKM35Z256VLL7R are defined in Section 5.2 of the KM35 Sub-Family Data Sheet Rev. 2, covering signal multiplexing for all 100 pins including AFE, LCD, tamper, and communication interfaces. Migration between packages requires PCB redesign but preserves software investment across the KM35 family.