Texas Instruments FPC401RHUR

Overview

FPC401RHUR from Texas Instruments is a quad-port low-speed signal aggregator IC designed for SFP+, QSFP+, and SAS pluggable module control. It supports I²C (up to 1 MHz) or SPI (up to 10 MHz) host interface, provides <50 µs multi-port write latency in SPI mode, integrates programmable LED drivers, and features broadcast-mode writes across all four ports. It enables localized port control under press-fit connectors in ToR switches.

For engineers reviewing the FPC401RHUR datasheet, FPC401RHUR pinout, FPC401RHUR application, or FPC401RHUR equivalent, key selection criteria include its WQFN-56 package with exposed thermal pad, dual-voltage I/O support (1.8–3.3 V), compatibility with SFF-8431/8436/8449 management interfaces, and ability to eliminate discrete I²C muxes and FPGA-based control logic.

Technical Context

The FPC401RHUR implements a dedicated 100-kHz/400-kHz I²C interface per port and supports automatic pre-fetching of user-specified registers from connected modules. Its interrupt generation is configurable per port for critical events, eliminating continuous polling.

It operates with separate host-side I/O voltage (1.8–3.3 V), supports broadcast writes across all four ports simultaneously, and allows cascading multiple FPC401RHUR devices to manage up to 56 total ports via one host interface - enabling scalable, high-density port control architectures.

Key Specifications

Pinout & Package

The FPC401RHUR is housed in a 56-pin WQFN (RHU) package measuring 5.00 mm × 11.00 mm with 0.5-mm pitch and an exposed thermal pad requiring PCB soldering for thermal and mechanical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-port signal aggregation applications.

Compared with LAN9303 and ADM1278, the FPC401RHUR uniquely delivers integrated SFF-compliant port control, broadcast register access, and programmable LED drivers in a single WQFN-56 package - making it the only solution purpose-built for high-density optical module aggregation without external logic.

Availability

FPC401RHUR is available at Aetrix Electronics and suitable for ToR switches, video routers, SAS enclosures, and aggregation switches requiring stable component supply and long-term industrial lifecycle support.

Supply support for FPC401RHUR 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The FPC401RHUR belongs to TI's port control and module management IC product line, engineered specifically to simplify optical interconnect infrastructure by consolidating low-speed signal handling at the connector level.

FAQ

What communication protocols does the FPC401RHUR support for host interface?

The FPC401RHUR supports both I²C (up to 1 MHz) and SPI (up to 10 MHz) host interfaces, selected via hardware pin configuration. This dual-interface capability allows system designers to choose based on speed requirements and existing host controller resources. The FPC401RHUR uses standard I²C addressing and SPI frame formats without proprietary extensions, ensuring straightforward integration. Both interfaces provide full register access to all four ports and support broadcast commands.

Does the FPC401RHUR require external components for LED driving?

No, the FPC401RHUR integrates four programmable LED drivers (LED0–LED3), each capable of driving common-anode or common-cathode indicators with adjustable current and timing. These drivers support 8-bit dimming resolution and configurable blink periods without external transistors or current-limiting resistors. The FPC401RHUR's internal drivers eliminate the need for discrete LED driver ICs or GPIO-expander solutions in optical module applications.

How does the FPC401RHUR handle hot-plug detection for SFP+/QSFP+ modules?

The FPC401RHUR monitors the MOD_ABS (module present) signal on each port and generates configurable interrupt events upon insertion or removal. It also supports automatic polling of module EEPROMs post-insertion to validate compliance and populate cached registers. The FPC401RHUR's interrupt output (INT pin) signals the host immediately, enabling sub-100-ms response times. This behavior is defined in SFF-8431 and SFF-8436 and requires no host-side polling.

Can multiple FPC401RHUR devices be cascaded, and how many ports can they manage collectively?

Yes, up to 14 FPC401RHUR devices can be cascaded using daisy-chained I²C or shared SPI bus architectures to manage 56 total ports. Each device retains independent addressability while supporting broadcast writes across the entire chain. The FPC401RHUR's address pins allow unique I²C addresses, and its SPI chip-select lines enable selective access. This scalability is documented in the SNLS553 datasheet and validated in TI's FPC401 EVM reference design.

What is the thermal pad requirement for the FPC401RHUR WQFN package?

The FPC401RHUR's exposed thermal pad must be soldered to a solid copper thermal plane on the PCB to ensure reliable thermal dissipation and mechanical stability. TI recommends a minimum of 68% solder paste coverage and at least four thermal vias (1.28 mm diameter) connecting the pad to inner-layer ground planes. Failure to properly attach the thermal pad may result in parametric drift or premature failure under sustained operation at 85°C ambient.