TMS320C6421ZWT5 DSP: A Full Technical Overview & Specs

Meta Description: Full technical overview for the TMS320C6421ZWT5 DSP. This guide covers the datasheet, specs, pinout, and legacy programming for this TI PowerQUICC II processor.

1.0 TMS320C6421ZWT5 Datasheet Overview

If you're an engineer, technician, or supply chain manager working with long-life-cycle equipment, the part number TMS320C6421ZWT5 is a name you'll recognize. This isn't a chip you'll find in a new 2025-era smartphone. This is a legacy workhorse, a high-performance Digital Signal Processor (DSP) from the Texas Instruments TMS320 family that was the engine behind a generation of video, imaging, and telecommunications hardware.

Why are we talking about a 15-year-old chip? Because the global market for Maintenance, Repair, and Operations (MRO) for this equipment is massive. A 2023 report on industrial automation highlighted that the average lifespan of critical factory equipment often exceeds 15-20 years. When a $50,000 medical imaging machine or a $100,000 telecom rack fails, you don't "just upgrade it." You repair it.

And that repair often hinges on sourcing this one specific, obsolete component. This guide is your technical deep-dive into the TMS320C6421ZWT5 datasheet. We'll cover its specs, pinout, and the critical (and tricky) legacy software you need to work with it.

1.1 What is the TMS320C6421ZWT5?

The TMS320C6421ZWT5 (often shortened to C6421) is a 32-bit, fixed-point Digital Signal Processor. It was developed by Texas Instruments and is part of the TMS320C64x+™ generation.

Its core purpose was to provide a low-cost, high-performance platform for applications that needed to move and process large streams of data in real-time. This made it a go-to choice for:

• Video Processing: Compressing and decompressing digital video streams.
• Imaging: Analyzing data from medical (CT, MRI) or industrial (machine vision) scanners.
• Telecommunications: Handling voice and data packets in carrier-grade equipment.

1.2 The TMS320C64x+ DSP Core: VLIW Architecture

This isn't a simple microcontroller. The C64x+ core is a VLIW (Very Long Instruction Word) powerhouse. This architecture allows it to execute up to eight 32-bit instructions in a single clock cycle.

Analogy: Think of a standard processor as a single-lane road. A VLIW processor is an eight-lane superhighway. For the right kind of traffic (like processing pixels in an image or samples in an audio stream), it is incredibly fast and efficient. This parallel processing capability is what makes it a DSP.

1.3 Decoding the Part Number: TMS320C6421ZWT5

The part number is a technical code that tells you exactly what you're holding.

• TMS320: The Texas Instruments Digital Signal Processor family.
• C6421: The specific device model.
• ZWT: This is the package type: a 361-pin MicroStar BGA (Ball Grid Array).
• 5: This is the speed grade, indicating a 500 MHz clock speed.

2.0 Status in 2025: A Critical Legacy Processor

2.1 A Legacy 500MHz Video/Telecom Processor

The TMS320C6421ZWT5 was a high-performance part for its time, offering 500 MHz of processing power (4000 MIPS) in a low-cost package. It was a "media processor" before the term was common, designed to handle the complex math of video codecs and communication protocols.

2.2 Obsolescence & MRO (Maintenance, Repair, Operations)

Official Status: OBSOLETE / END-OF-LIFE (EOL)

Let's be clear: the TMS320C6421ZWT5 and the entire C642x family are obsolete. They are no longer manufactured by Texas Instruments and are Not Recommended for New Designs (NRND).

This chip's entire value today is as a critical MRO component. Because it is in a specific 361-ball BGA package and requires a massive amount of legacy software, there is no modern, drop-in replacement. Repairing a board with a failed C6421 requires sourcing a genuine, identical part.

3.0 TMS320C6421ZWT5 Applications

3.1 Primary Use: Video, Imaging, and Telecom

You will find this processor in long-life-cycle equipment where high-speed data streaming is essential.

• Video Conferencing: Codec (H.263, H.264) processing.
• Digital Video: Recorders (DVRs) and video-over-IP gateways.
• Telecommunications: 3G/4G wireless infrastructure, VoIP gateways, and echo cancellation.
• Industrial: High-speed machine vision and inspection systems.

3.2 Medical and Industrial Imaging

A key application was in medical imaging. The C6421 had the raw processing power to handle data streams from MRI, CT, and ultrasound sensors, performing the filtering and image reconstruction in real-time. This is a primary reason why the part is still in high demand for MRO—you can't simply stop servicing a million-dollar MRI machine because a processor is obsolete.

4.0 TMS320C6421ZWT5 Key Technical Specifications

When you're sourcing a replacement, matching the TMS320C6421ZWT5 specs is vital.

4.1 Core Performance and Memory Specs

Feature	Specification
Family	TMS320C64x+ (C642x)
Core Speed	500 MHz
Performance	4000 MIPS
L1P Cache (Program)	32 KB
L1D Cache (Data)	32 KB
L2 RAM/Cache	128 KB
Core Voltage (VDD)	1.2V
I/O Voltage (VDDIO)	3.3V (1.8V for DDR2)
Package	361-pin MicroStar BGA (ZWT)
Temperature	Commercial (0°C to 90°C)

4.2 Peripheral and I/O Specs

* **Ethernet:** 1x 10/100 Ethernet MAC (EMAC). * **External Memory (EMIF):** 16-bit DDR2 (up to 200MHz) or 16-bit Async (SRAM, Flash). * **Serial Ports:** 2x McBSP (Multi-channel Buffered Serial Port), 2x I²C, 1x SPI. * **Timers:** 3x 64-Bit General-Purpose Timers. * **Host Port:** 1x 16-bit Host Port Interface (HPI16).

4.3 TMS320C6421ZWT5 vs. TMS320C6424: A Key Comparison

A common point of confusion is the C6421 vs. the C6424. They are not interchangeable. The C6424 is the C6421's "bigger brother."

Feature	TMS320C6421ZWT5	TMS320C6424ZWT (Typical)
Clock Speed	500 MHz	600 MHz
L2 RAM/Cache	128 KB	256 KB
Video Port Interface (VPI)	No	Yes (Critical for video I/O)
PCI Bus	No	Yes (32-bit, 33/66 MHz)
Ethernet	1x 10/100 EMAC	1x 10/100/1000 EMAC (Gigabit)
Use Case	Cost-effective DSP	High-I/O Video & Comms Hub

The takeaway: You cannot replace a C6424 with a C6421, as it lacks the VPI and PCI. You might be able to replace a C6421 with a C6424 (if the software is compatible), but it's not a guaranteed drop-in.

5.0 TMS320C6421ZWT5 Pinout and Programming

5.1 ZWT (361-BGA) Package Pinout

The TMS320C6421ZWT5 pinout is a 361-ball MicroStar BGA. This high-density package requires a BGA rework station for replacement and X-ray inspection to verify solder joints.

[Insert image: A clear pinout diagram of the TMS320C6421ZWT5 in the ZWT-361 package, showing the A1, B1, etc. ball grid.] Alt Text: TMS320C6421ZWT5 pinout diagram for the ZWT-361 BGA package.

5.2 How to Program the TMS320C6421ZWT5

This is the biggest hurdle for engineers working with these legacy parts. You cannot use the latest TI software.

1. Required Software: You must find and install a legacy version of Texas Instruments' Code Composer Studio (CCS). Modern CCS versions (v7+) do not support the C642x. You will need a version like CCS v3.3 or v4.x.
2. OS Compatibility: This old software often requires a 32-bit operating system like Windows XP or Windows 7 (32-bit). A virtual machine (VM) is your best friend here.
3. Programming Hardware: You need a compatible JTAG Emulator (debug probe). The modern XDS200/XDS2xx series may not work. You will need a legacy XDS510 or XDS560-class emulator.
4. Boot Process: The C6421 typically boots from an external 16-bit parallel flash, loading its program into DDR2 RAM at startup. The JTAG emulator is used to flash this memory or to load code directly into RAM for debugging.

Conclusion: A Specialized Core for Legacy Infrastructure

The TMS320C6421ZWT5 is not just another part number; it's a highly integrated system-on-a-chip that was the engine for a generation of high-speed video and networking hardware. Its powerful VLIW core made it a performance champion, but today, its legacy status makes it a critical MRO challenge.

As an engineer or supply chain manager, you know that a "line-down" situation costs more than just the price of a chip. It costs time, labor, and customer trust. Don't let a hard-to-find part be your bottleneck.

AichipLink specializes in sourcing high-quality, genuine legacy components, including communications processors from the TI TMS320 family. If you need to secure your supply of the TMS320C6421ZWT5, contact us today for a quote and keep your critical infrastructure running.

 

 

 

 

 

Written by Jack Elliott from AIChipLink.

 

AIChipLink, one of the fastest-growing global independent electronic   components distributors in the world, offers millions of products from thousands of manufacturers, and many of our in-stock parts is available to ship same day.

 

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