NXP Semiconductors MIMXRT685SFVKBR

Overview

MIMXRT685SFVKBR from NXP Semiconductors is a dual-core Arm Cortex-M33 + Cadence Xtensa HiFi4 audio DSP microcontroller in VFBGA176 package, operating at up to 300 MHz (M33) and 600 MHz (HiFi4), with 4.5 MB shared SRAM and 128 KB TCM, designed for real-time voice processing in smart speakers and always-on audio edge devices.

For engineers reviewing the MIMXRT685SFVKBR datasheet, MIMXRT685SFVKBR pinout, MIMXRT685SFVKBR application, or MIMXRT685SFVKBR equivalent, key selection factors include dual-core asymmetric execution, on-chip AES256/PUF security, FlexSPI with 32 KB cache and OTF decryption, 8-channel digital microphone interface with Voice Activation Detect, and triple I/O voltage domains supporting mixed-voltage peripheral interfacing.

Technical Context

The MIMXRT685SFVKBR implements tightly coupled inter-processor communication via hardware mailboxes and semaphores, with a shared 4.5 MB SRAM space partitioned into 30 configurable blocks-each independently assignable to Cortex-M33, HiFi4, or DMA engines, and controllable for retention or power-off. The HiFi4 accesses RAM through a dedicated 256-bit interface with single-cycle cache, while the M33 uses the 32-bit AHB bus.

Its clock architecture includes a main system PLL supporting CPU operation without external high-frequency crystals, an independent fractional-divider audio PLL, and a second PLL output dedicated to the HiFi4 core when frequency separation is required. Power management supports deep-sleep mode with synchronous serial interfaces clocked by the 32 kHz RTC oscillator and wake-up via GPIO, RTC, or OS Event Timer interrupts.

Key Specifications

Pinout & Package

VFBGA176 package: 176-ball thin fine-pitch ball grid array, 9 mm × 9 mm × 0.98 mm body, 0.65 mm ball pitch, lead-free and RoHS compliant. Designed for automated SMT assembly and thermal performance in audio edge applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-core audio microcontroller applications.

Compared with MIMXRT685SFVKBR, the MIMXRT685SFFOB offers superior thermal and I/O scalability in fan-out packaging, while MIMXRT685SVFVKB delivers identical hardware with pre-integrated voice software-making MIMXRT685SFVKBR the optimal choice for custom voice algorithm development and cost-sensitive volume deployments where software stack is developed in-house.

Availability

MIMXRT685SFVKBR is available at Aetrix Electronics and suitable for smart speaker front-ends, always-on voice assistant modules, and industrial voice-controlled HMIs requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for production ramp.

Supply support for MIMXRT685SFVKBR 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 applications, with headquarters in Eindhoven, Netherlands.

The RT600 family-including MIMXRT685SFVKBR-is engineered specifically for high-fidelity, low-power voice and audio edge processing, combining Arm and Xtensa architectures to deliver deterministic real-time performance in resource-constrained embedded systems.

FAQ

What is the maximum operating frequency of each core in the MIMXRT685SFVKBR?

The MIMXRT685SFVKBR features an Arm Cortex-M33 core rated for up to 300 MHz and a Cadence Xtensa HiFi4 DSP core rated for up to 600 MHz. These frequencies are achievable under specified voltage (1.8 V ±5%) and temperature (-20 °C to +85 °C) conditions. Both cores operate independently with dedicated clock domains, allowing asymmetric workload distribution without contention. The MIMXRT685SFVKBR datasheet confirms these values in Section 1 General Description and Table 2 Ordering Options.

Does the MIMXRT685SFVKBR support secure boot and runtime encryption?

Yes, the MIMXRT685SFVKBR supports secure boot via ROM-based bootloader with configurable boot sources (FlexSPI, SDIO, UART, USB), AES256 encryption engine with on-the-fly decryption for FlexSPI XIP, SHA1/SHA2 hash module for firmware integrity verification, and Physical Unclonable Function (PUF) for hardware-derived key generation. These features are documented in Sections 2 Features and Benefits and 1.1 Peripherals of the RT600 datasheet, and are fully implemented in the MIMXRT685SFVKBR silicon revision B.

How many GPIO pins are available on the MIMXRT685SFVKBR in its VFBGA176 package?

The MIMXRT685SFVKBR in VFBGA176 package provides 96 general-purpose I/O pins, distributed across PIO0, PIO1, and PIO2 port groups. This count is confirmed in Table 2 (Ordering Options) of the RT600 datasheet, which lists "GPIO: 96" for both MIMXRT685SFVKB and MIMXRT685SVFVKB variants-identical package and pinout to MIMXRT685SFVKBR. All 96 pins support interrupt generation, pattern matching, and configurable pull-up/down resistors.

Can the MIMXRT685SFVKBR directly interface with PDM microphones?

Yes, the MIMXRT685SFVKBR includes a dedicated digital microphone (DMIC) interface supporting up to eight PDM input channels with integrated decimation filters and Voice Activation Detect (VAD) logic. Pins DMIC_CLK and DMIC_DATA[0:7] are assigned in the VFBGA176 pinout (Table 4), and the interface supports DMA-driven streaming to SRAM. This capability eliminates external PDM-to-I2S converters and is explicitly listed in Section 1.1 Peripherals and Table 2 as a standard feature of all RT685 variants including MIMXRT685SFVKBR.

What is the purpose of the triple I/O power supply in the MIMXRT685SFVKBR?

The triple I/O power supply (VDDIO0/VDDIO1/VDDIO2) in the MIMXRT685SFVKBR allows independent voltage configuration (1.71–3.6 V) for different GPIO port groups. This enables direct interfacing with peripherals operating at mismatched logic levels-such as 1.8 V sensors, 3.3 V audio codecs, or 2.5 V PMICs-without external level shifters. The feature is detailed in Section 2 Features and Benefits ("Triple I/O power") and Section 4.1 Ordering Options, and applies identically to all RT685 packages including MIMXRT685SFVKBR.