Texas Instruments FPC402RHUR

Overview

FPC402RHUR from Texas Instruments is a quad-port low-speed signal aggregator IC designed for optical module management in high-density networking hardware. It consolidates I²C, status inputs (IN_A/B/C), and control outputs (OUT_A/B/C/D) across four SFP/QSFP/OSFP ports into a single host interface, supports up to 1 MHz I²C or 10 MHz SPI host communication, operates with dual supplies (VDD1 = 3.3 V, VDD2 = 1.8–3.3 V), and delivers programmable LED blinking/dimming via dedicated OUT_C/OUT_D drivers.

For engineers reviewing the FPC402RHUR datasheet, FPC402RHUR pinout, FPC402RHUR application, or FPC402RHUR equivalent, this device addresses port-count scalability, PCB routing reduction under press-fit connectors, elimination of discrete I²C muxes and FPGA-based control logic, and synchronized LED status indication across multi-controller systems - all critical in ToR switch, baseband unit, and storage rack designs.

Technical Context

The FPC402RHUR implements a dual-voltage architecture: VDD1 powers internal logic and port-side I²C masters (MOD_SCL/SDA), while VDD2 independently supplies host-side CTRL[4:1] pins - enabling interoperability with 1.8 V, 2.5 V, or 3.3 V host controllers. Its PROTOCOL_SEL pin selects between I²C (up to 1 MHz Fast-mode Plus) and SPI (up to 10 MHz) host interfaces, with dedicated open-drain MOD_SCL/SDA outputs per port supporting SFF-8431/8436/8449 compliance.

Each of the four ports features four bidirectional low-speed control/status channels: IN_A/B/C for module presence, fault, and loss-of-signal detection; OUT_A/B for Tx_Disable/ResetL and LPMode control; and OUT_C/D for active-low LED driving with built-in dimming and blink timing. The device supports broadcast writes across cascaded FPC402RHUR units and automatic prefetching of user-defined module registers to minimize host polling overhead.

Key Specifications

Pinout & Package

The FPC402RHUR is housed in a 56-pin WQFN package (RHU) measuring 5.00 mm × 11.00 mm, optimized for bottom-side PCB placement beneath press-fit optical connectors to minimize trace length and layer congestion.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-port optical module control applications.

Compared with FPC401RHUR, the FPC402RHUR adds SPI support, broadcast capability, and data prefetch - enabling scalable multi-controller systems. Against MAX5980GTJ+, it trades power control for comprehensive signal aggregation and LED management, making it unsuitable for rail supervision but optimal for status/control consolidation.

Availability

FPC402RHUR is available at Aetrix Electronics and suitable for ToR switch, wireless infrastructure BBU, and storage rack applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing for industrial-grade deployments.

Supply support for FPC402RHUR 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 leader specializing in analog, embedded processing, and connectivity solutions, with decades of expertise in high-reliability communications ICs.

The FPC402RHUR belongs to TI's optical module interface product line, engineered specifically to reduce system complexity in high-port-count networking equipment by replacing FPGA-based glue logic with integrated, standards-compliant port control.

FAQ

What host interface protocols does the FPC402RHUR support?

The FPC402RHUR supports two mutually exclusive host-side protocols selected by the PROTOCOL_SEL pin: I²C up to 1 MHz (Fast-mode Plus compliant) or SPI up to 10 MHz. In I²C mode, CTRL1–CTRL4 function as SCL, SDA, SET_ADDR_N, and ADDR_DONE_N; in SPI mode, they become SCK, SS_N, MOSI, and MISO. The FPC402RHUR does not support concurrent or auto-sensing operation between the two interfaces.

How does the FPC402RHUR handle LED control for optical modules?

The FPC402RHUR provides dedicated active-low LED drivers on OUT_C[3:0] and OUT_D[3:0], each capable of sinking up to 18 mA. These outputs support programmable blink frequency (0.1–10 Hz), duty cycle (10–90%), and dimming (8-level current control). The FPC402RHUR uses internal timers - no host CPU involvement is required once configured - and supports synchronized blinking across multiple FPC402RHUR units via SPI_LED_SYNC in SPI mode.

Can multiple FPC402RHUR devices be cascaded, and how is communication managed?

Yes, up to 14 FPC402RHUR devices can be cascaded to manage 56 ports total. They share a common host interface (I²C or SPI) using individual I²C addresses or daisy-chained SPI. Broadcast writes - enabled via register bit - allow simultaneous configuration of identical registers across all devices. Interrupts (HOST_INT_N) can be wired-OR'd to a single host line, with source identification handled through device-specific status registers in the FPC402RHUR.

What is the role of the CAPL pin on the FPC402RHUR?

The CAPL pin on the FPC402RHUR requires connection to a single 2.2-µF capacitor tied to GND. This capacitor stabilizes the internal low-dropout regulator that supplies core logic voltage, ensuring reliable power-on reset (TPOR) behavior and noise immunity during dynamic port activity. Omitting or undersizing the CAPL capacitor may cause intermittent initialization failures or I²C communication dropouts, especially under hot-plug transients.

Does the FPC402RHUR support hot-plug detection and automatic module enumeration?

Yes, the FPC402RHUR natively supports hot-plug detection via its weak-pullup IN_A[3:0] inputs (ModPrsL/Mod_ABS), which trigger configurable interrupts on module insertion/removal. It does not perform autonomous enumeration; instead, it provides ready-access registers indicating port presence, fault state, and LOS condition. Host firmware uses these flags to initiate I²C reads of module EEPROM (via MOD_SDA/SCL), with optional prefetch acceleration for frequently accessed DOM registers.