Texas Instruments FPC401RHUT

Overview

FPC401RHUT from Texas Instruments is a quad-port low-speed signal aggregator IC for SFP+, QSFP+, and SAS pluggable modules, supporting I²C (up to 1 MHz) and SPI (up to 10 MHz) host interfaces, <50 µs multi-port write latency in SPI mode, and automatic pre-fetching of user-specified module registers. It serves as centralized port control logic in high-density switch/router line cards.

For engineers reviewing the FPC401RHUT datasheet, FPC401RHUT pinout, FPC401RHUT application, or FPC401RHUT equivalent, key selection criteria include its QFN-56 package with exposed thermal pad, dual-mode host interface, broadcast-write capability across four ports, programmable LED dimming/blink control, and compatibility with SFF-8431/SFF-8436/SFF-8449 management protocols.

Technical Context

The FPC401RHUT implements a dedicated 100-kHz/400-kHz I²C interface per port for compliance with SFF-8431/8436/8449, plus general-purpose I/Os for LED driving and power-switch control. Its internal register map enables configurable interrupt events and user-defined prefetch sequences.

It supports cascading up to 14 devices for 56-port control via shared host bus, uses separate 1.8-V to 3.3-V host-side I/O supply, and places all low-speed signal conditioning locally beneath press-fit connectors to minimize PCB routing congestion and reduce FPGA/CPLD I/O count requirements.

Key Specifications

Pinout & Package

Package: WQFN-56 (RHU), 5.00 mm × 11.00 mm body, 0.8 mm max height, 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 MAX5487ATJ+ and TCA9548A, the FPC401RHUT delivers integrated port intelligence - combining I²C aggregation, programmable LED control, interrupt event filtering, and register prefetch - reducing total system component count and host software overhead in dense pluggable-module systems.

Availability

FPC401RHUT is available at Aetrix Electronics and suitable for ToR switches, video routers, SAS enclosures, and aggregation switch modules requiring stable component supply and long-term industrial lifecycle support.

Supply support for FPC401RHUT 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 delivering analog and embedded processing solutions, with leadership in high-reliability interface and signal-chain ICs for communications infrastructure.

The FPC401RHUT belongs to TI's port control and module management product line, designed specifically to simplify low-speed signal handling in high-port-count optical and storage interconnect systems.

FAQ

What host interface modes does the FPC401RHUT support?

The FPC401RHUT supports both I²C (up to 1 MHz) and SPI (up to 10 MHz) host interfaces, selected at power-up via strap pin configuration. This dual-mode flexibility allows integration with legacy I²C-based management systems or high-speed SPI-capable microcontrollers. The FPC401RHUT automatically adapts its command protocol and timing based on the selected mode, ensuring reliable communication without host firmware rework.

How does the FPC401RHUT handle LED control for port status indication?

The FPC401RHUT integrates four dedicated current-sink LED driver outputs (LED0–LED3), each supporting programmable blink frequency, duty cycle, and dimming levels per port. These drivers eliminate external LED driver ICs and allow dynamic status encoding - such as solid-on for link-up, slow-blink for fault, and PWM-dimmed for low-power standby. The FPC401RHUT executes LED behavior autonomously after initial configuration, reducing host CPU load.

Can multiple FPC401RHUT devices be cascaded for higher port counts?

Yes, up to 14 FPC401RHUT devices can be cascaded via shared I²C or SPI bus to manage 56 ports with a single host interface. Each device uses configurable address pins to avoid bus contention, and broadcast commands propagate across the chain to synchronize writes. This architecture maintains deterministic latency and simplifies firmware design for large-scale switch/router platforms using the FPC401RHUT.

What standards does the FPC401RHUT comply with for optical module management?

The FPC401RHUT complies with SFF-8431 (SFP+), SFF-8436 (QSFP+), and SFF-8449 (SAS) low-speed management interface specifications, including dedicated 100-kHz and 400-kHz I²C channels per port. It correctly interprets module EEPROM addresses, page select mechanisms, and alarm/warning flag mappings defined in those standards - ensuring seamless interoperability with certified optical and active copper modules in production networks.

What is the thermal pad requirement for the FPC401RHUT's WQFN-56 package?

The FPC401RHUT's WQFN-56 (RHU) package requires the exposed thermal pad to be soldered to a dedicated PCB copper pour for thermal dissipation and mechanical stability. TI recommends minimum 68% solder paste coverage and use of thermal vias under the pad connected to inner-layer ground planes. Failure to properly attach the thermal pad may result in degraded thermal performance and long-term reliability risk for the FPC401RHUT in sustained operation.