Texas Instruments ONET8541TYS4

Overview

ONET8541TYS4 from Texas Instruments is a 11.3 Gbps limiting transimpedance amplifier (TIA) for optical receivers, featuring 9 GHz bandwidth, 4 kΩ differential small-signal transimpedance, 0.95 µA_RMS input-referred noise, and integrated RSSI functionality. It operates from a single 3.3 V ±10% supply, dissipates 90 mW typical power, and targets high-speed fiber optic links including 10G Ethernet and SONET OC-192.

For engineers reviewing the ONET8541TYS4 datasheet, ONET8541TYS4 pinout, ONET8541TYS4 application, or ONET8541TYS4 equivalent, this die-form TIA requires careful attention to bond pad layout, photodiode parasitics, supply filtering, and RSSI current-sinking resistor selection to achieve –20 dBm sensitivity and low deterministic jitter at 10.3125 Gbps.

Technical Context

The ONET8541TYS4 integrates a transimpedance amplifier stage with automatic gain control (AGC), a limiting voltage amplifier, and CML output buffers with on-chip 50 Ω back-termination. Its signal path supports PIN photodiodes biased via internal 220 Ω filter resistors and delivers differential outputs compliant with SFF-8431 requirements.

It features dual RSSI outputs-RSSI_IB for internally biased receivers and RSSI_EB for externally biased configurations-with current-mode outputs requiring external resistive loads. The die includes separate VCC_IN and VCC_OUT supplies, on-chip supply filter capacitors, and operates across –40°C to +100°C case temperature.

Key Specifications

Pinout & Package

ONET8541TYS4 is supplied as a bare die in WAFERSALE (YS) format, with dimensions 870 µm × 1036 µm and thickness 203 ± 13 µm. Bond pads are gold-plated, 105 µm × 65 µm, arranged in a fixed layout optimized for TO-can packaging with ground-signal-ground (GSG) photodiode integration.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar limiting transimpedance amplifier applications.

Compared with ONET8541TYS4, MAX3964A trades RSSI and bandwidth for lower cost and simpler biasing, while LMH6525 offers higher data-rate headroom but sacrifices noise performance and integration density-making ONET8541TYS4 optimal for space-constrained, RSSI-dependent telecom modules.

Availability

ONET8541TYS4 is available at Aetrix Electronics and suitable for 10G Ethernet optical modules, SONET OC-192 line cards, 10G EPON OLTs, and Fibre Channel HBAs requiring stable component supply, wafer-level sourcing, and long-lifecycle support.

Supply support for ONET8541TYS4 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 high-speed interface solutions, with decades of expertise in optical networking ICs.

The ONET8541TYS4 belongs to TI's ONET family of high-speed optical receiver ICs, designed specifically for compact, low-power, high-sensitivity fiber-optic links in telecom, datacom, and enterprise infrastructure.

FAQ

What is the primary function of the ONET8541TYS4 in an optical receiver?

The ONET8541TYS4 serves as a limiting transimpedance amplifier that converts weak photodiode current signals into robust CML-compatible differential voltage outputs. It performs automatic gain control, DC offset cancellation, and RSSI generation-all within a single die. Its design enables ONET8541TYS4 to deliver –20 dBm sensitivity and sub-14 ps deterministic jitter at 10.3125 Gbps in compact TO-can packages.

Does the ONET8541TYS4 require external termination resistors on its CML outputs?

No, the ONET8541TYS4 integrates 50 Ω on-chip pull-up resistors to VCC_OUT on both OUT+ and OUT– pins, eliminating the need for external termination. However, AC coupling capacitors (e.g., 0.1 µF) are mandatory between ONET8541TYS4 outputs and the next-stage receiver to block DC offset and ensure proper common-mode voltage alignment.

How does the RSSI functionality work on the ONET8541TYS4, and what are the differences between RSSI_IB and RSSI_EB?

ONET8541TYS4 provides two RSSI outputs: RSSI_IB mirrors input signal strength when the photodiode is biased via internal FILTER pins, while RSSI_EB does so under external bias conditions (e.g., APD drivers). Both are current-mode outputs requiring external resistors to ground; voltage at either pad must stay ≤ V_CC – 0.65 V. RSSI_IB is calibrated for internal bias accuracy; RSSI_EB offers flexibility but lower inherent precision.

What package form is the ONET8541TYS4 delivered in, and how is it intended to be assembled?

ONET8541TYS4 is shipped as a bare die in WAFERSALE (YS) format-i.e., as a single die on a wafer fragment-not as packaged units. It is designed for flip-chip or wire-bond assembly into hermetic TO-46 or TO-56 cans with ground-signal-ground photodiode layouts. TI provides detailed bond pad coordinates and TO-can layout examples to guide mechanical integration and parasitic control.

What are the critical layout considerations for achieving specified performance with the ONET8541TYS4?

Key layout rules for ONET8541TYS4 include: minimizing IN-pad capacitance (<0.2 pF) via low-C_PD photodiodes and short bond wires (<0.5 nH); using symmetrical, impedance-controlled traces for OUT+/OUT–; connecting ≥4 GND pads with low-inductance bonds; and placing external RSSI load resistors close to RSSI_IB/RSSI_EB pads. Failure to control these parasitics degrades bandwidth, increases jitter, and reduces sensitivity below –20 dBm.