Texas Instruments USBN9604-28MX/NOPB

Overview

USBN9604-28MX/NOPB from National Semiconductor is a full-speed USB 1.1 node controller IC integrating transceiver, 3.3V regulator, Serial Interface Engine (SIE), seven endpoint FIFOs (1×8-byte control + 6×64-byte data), 8-bit parallel/MICROWIRE interface, and enhanced DMA engine. It operates at 5V or 3.3V, supports 24 MHz crystal input with internal 48 MHz PLL clock generation, and targets embedded host-peripheral bridge applications in industrial instrumentation and legacy PC peripheral controllers.

For engineers reviewing the USBN9604-28MX/NOPB datasheet, USBN9604-28MX/NOPB pinout, USBN9604-28MX/NOPB application, or USBN9604-28MX/NOPB equivalent, key selection criteria include its non-multiplexed/multiplexed CPU interface flexibility, automatic DMA (ADMA) mode for CPU-independent bulk transfers, programmable interrupt polarity, and pin-to-pin compatibility with USBN9602-28M for drop-in upgrades.

Technical Context

The USBN9604-28MX/NOPB implements a complete USB 1.1-compliant Physical Layer (PHY) and Media Access Controller (MAC) in its SIE, including NRZI decoding, bit stuffing/unstuffing, CRC generation/checking, and clock recovery from 48 MHz derived via PLL from 24 MHz input. Its transceiver meets USB 1.1 Chapter 7 electrical requirements with differential receiver, single-ended receivers (0.8–2.0 V threshold), and slew-rate-controlled transmitter.

Endpoint Pipe Controller (EPC) manages seven dedicated FIFO-based pipes: one bidirectional control endpoint (EP0) and six unidirectional endpoints (three TX, three RX), each with autonomous NAK/STALL response logic and PID toggling. The 8-bit parallel interface supports both Intel-compatible multiplexed (ALE-driven) and non-multiplexed (A0-addressed) modes selected by MODE1–MODE0 pins.

Key Specifications

Pinout & Package

USBN9604-28MX/NOPB is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 300 mil body width, compatible with standard SO-28 PCB footprints and reflow soldering profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar USB node controller applications.

Compared with USBN9603-28MX/NOPB, the USBN9604-28MX/NOPB offers improved clock synchronization during hardware reset, while CP2102-GM provides turnkey UART bridging but sacrifices endpoint flexibility and host-CPU interfacing capability essential for custom USB device development.

Availability

USBN9604-28MX/NOPB is available at Aetrix Electronics and suitable for industrial data acquisition, legacy peripheral bridging, and embedded test instrumentation requiring stable component supply and long-term lifecycle support.

Supply support for USBN9604-28MX/NOPB 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

National Semiconductor was a U.S.-based semiconductor company specializing in analog and interface ICs, acquired by Texas Instruments in 2011; its legacy USB controller portfolio remains widely deployed in industrial systems.

The USBN960x family was designed as a cost-optimized, full-speed USB node controller for resource-constrained embedded systems requiring minimal external components and flexible host interface options.

FAQ

What USB specification versions does the USBN9604-28MX/NOPB support?

The USBN9604-28MX/NOPB supports USB Specification versions 1.0 and 1.1 only - it is a full-speed (12 Mbps) node controller and does not implement USB 2.0 high-speed (480 Mbps) functionality. All SIE logic, transceiver behavior, and descriptor handling comply strictly with USB 1.1 requirements, including Chapter 7 electrical compliance and Chapter 8 protocol stack implementation. USBN9604-28MX/NOPB cannot enumerate or operate on USB 2.0 hubs unless operating in full-speed fallback mode.

Does the USBN9604-28MX/NOPB require an external crystal, or can it use an external clock source?

The USBN9604-28MX/NOPB accepts either a 24 MHz fundamental crystal connected between XIN and XOUT, or a 24 MHz square-wave clock signal applied to XIN with XOUT left unconnected. The internal oscillator circuit is optimized for AT-cut crystals with 20 pF load capacitance and ≤50 Ω series resistance. Using an external clock eliminates crystal layout sensitivity but requires tight signal integrity control on the XIN trace to avoid jitter-induced USB packet errors. USBN9604-28MX/NOPB does not support frequencies other than 24 MHz for clock input.

How does the Automatic DMA (ADMA) mode function in the USBN9604-28MX/NOPB?

ADMA mode in the USBN9604-28MX/NOPB enables fully CPU-independent USB data transfers by chaining 64-byte packets up to 16 KB total (256 × 64 bytes). Once configured via DMACNTRL and DMACNT registers, the ADMA engine handles PID toggling, NAK recovery, and FIFO servicing without software intervention. This allows the host microcontroller to enter low-power states or service other tasks during sustained bulk transfers - a critical advantage in battery-powered or real-time embedded USBN9604-28MX/NOPB implementations.

What is the purpose of the V3.3 pin on the USBN9604-28MX/NOPB, and how should it be decoupled?

The V3.3 pin on the USBN9604-28MX/NOPB serves as either the output of the internal 3.3 V regulator (when enabled) or as an external 3.3 V supply input for the transceiver. When used as regulator output, it must be decoupled with a 1 µF tantalum capacitor to AGND - ceramic capacitors are insufficient due to ESR requirements specified in the datasheet. If the system operates at 3.3 V and the regulator is disabled, V3.3 becomes an input requiring clean, low-noise 3.3 V supply. USBN9604-28MX/NOPB's transceiver will not function without proper biasing of this pin.

Is the USBN9604-28MX/NOPB pin-compatible with the earlier USBN9602-28M device?

Yes - the USBN9604-28MX/NOPB is explicitly documented as pin-to-pin compatible with USBN9602-28M in the "Available in two packages" section of the datasheet, supporting drop-in replacement in existing SO-28 layouts. All signal names, pin positions, and DC/AC timing parameters match. However, USBN9604-28MX/NOPB adds DLL-based clock synchronization during hardware reset, which improves timing stability but does not affect pin-level interoperability. No PCB changes are required when upgrading from USBN9602-28M to USBN9604-28MX/NOPB.