NXP Semiconductors DSPB56721AF

Overview

DSPB56721AF from Freescale Semiconductor is a dual-core 24-bit audio DSP engineered for high-fidelity, multi-stream audio processing in automotive and consumer systems. It delivers 200 MIPS per core at 200 MHz internal clock, integrates two DSP56300 cores, on-chip ASRC, ESAI, S/PDIF, and Inter-Core Communication (ICC), and targets HD-Audio decoding (Dolby TrueHD, DTS-HD) in car audio amplifiers and A/V receivers.

For engineers reviewing the DSPB56721AF datasheet, DSPB56721AF pinout, DSPB56721AF application, or DSPB56721AF equivalent, key selection factors include its 80-pin LQFP package, absence of external memory interface (vs. DSP56720), 1.0 V core / 3.3 V I/O supply scheme, and dedicated audio peripherals including three ESAI modules and dual SHI interfaces.

Technical Context

The DSPB56721AF implements two independent DSP56300 24-bit CPU cores sharing 64 KB of on-chip RAM across eight 8-KB blocks, with dedicated DMA engines and arbitration logic. Its audio subsystem includes three Enhanced Serial Audio Interfaces (ESAI_1/2/3), one Asynchronous Sample Rate Converter (ASRC), and dual Serial Host Interfaces supporting SPI and I²C protocols.

Unlike the DSP56720, the DSPB56721AF omits the External Memory Controller (EMC) and HDI24 host interface, confirming its role as a self-contained, memory-limited audio co-processor optimized for deterministic real-time audio routing and effects processing rather than expandable system control.

Key Specifications

Pinout & Package

80-pin plastic LQFP package, 14 mm × 14 mm body, 0.65 mm lead pitch, exposed pad not specified. Pin functions validated per Figure 4 (DSP56721 80-Pin Package Pinout) in DSP56720EC Rev. 5.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-core audio DSP applications.

Compared with AK4128A and TMS320C6748, the DSPB56721AF provides native multi-channel audio I/O concurrency and hardware ASRC - reducing BOM cost and firmware development effort for automotive and home theater applications requiring ≥5.1-channel processing.

Availability

DSPB56721AF is available at Aetrix Electronics and suitable for automotive infotainment, premium home theater receivers, and professional studio monitor controllers requiring stable component supply and long-term production continuity.

Supply support for DSPB56721AF 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

Freescale Semiconductor (now part of NXP Semiconductors) is a fabless semiconductor company specializing in microcontrollers, analog, and digital signal processors for automotive, industrial, and networking markets.

The DSP5672x family, including DSPB56721AF, was designed specifically for high-performance, low-latency audio signal processing in resource-constrained embedded systems - emphasizing plug-and-play peripheral integration and deterministic real-time execution.

FAQ

What is the core voltage requirement for stable operation of the DSPB56721AF?

The DSPB56721AF requires a tightly regulated 1.0 V ±10% (0.9–1.1 V) core supply (CORE_VDD) for stable operation at 200 MHz. Deviation beyond this range risks timing violations or reset assertion. The datasheet specifies maximum core supply ramp time of 10 ms to ensure proper power-on reset behavior. DSPB56721AF must be powered with this precision rail to maintain 200 MIPS/core performance and avoid functional failure.

Does the DSPB56721AF support external SDRAM expansion like the DSP56720?

No, the DSPB56721AF does not support external SDRAM expansion. Unlike the DSP56720, which includes an External Memory Controller (EMC), the DSPB56721AF omits this interface entirely. Its memory subsystem relies solely on 64 KB of on-chip RAM distributed across eight 8-KB blocks. This architectural difference confirms DSPB56721AF's role as a fixed-function audio co-processor rather than a general-purpose system controller.

How many independent serial audio interfaces does the DSPB56721AF provide?

The DSPB56721AF provides three independent Enhanced Serial Audio Interfaces (ESAI_1, ESAI_2, ESAI_3), each supporting up to 8 TDM time slots and configurable as transmitter, receiver, or bidirectional. This enables simultaneous connection to multiple audio components - for example, ESAI_1 to ADCs, ESAI_2 to DACs, and ESAI_3 to digital amplifiers - without multiplexing or time-sharing constraints. DSPB56721AF's triple-ESAI capability is a key differentiator for complex multi-zone audio systems.

What clock sources does the DSPB56721AF accept for audio master timing?

The DSPB56721AF accepts either a 24.576 MHz crystal connected between EXTAL and XTAL pins (for low-jitter audio clock generation) or an external square-wave clock applied to EXTAL alone. The on-chip PLL generates internal 200 MHz core clocks and programmable audio sample rates (e.g., 44.1 kHz, 48 kHz, 96 kHz) from these sources. DSPB56721AF does not support spread-spectrum or variable-frequency clock inputs - only fixed-frequency crystal or clean square-wave reference.

Is the DSPB56721AF pin-compatible with any other members of the DSP5672x family?

No, the DSPB56721AF is not pin-compatible with the DSP56720 or the 144-pin variant of the DSP56721. It is exclusively offered in an 80-pin LQFP package (14 mm × 14 mm, 0.65 mm pitch), whereas the DSP56720 uses a 144-pin LQFP (20 mm × 20 mm, 0.5 mm pitch) and the DSP56721 144-pin variant uses identical dimensions to the DSP56720. PCB layout must be designed specifically for the 80-pin footprint of DSPB56721AF.