Texas Instruments ONET8531TYS9

Overview

ONET8531TYS9 from Texas Instruments is a 11.3 Gbps limiting transimpedance amplifier (TIA) optimized for optical receivers in SFP+ and 10G Ethernet systems. It delivers 4.5 kΩ differential small-signal transimpedance, 10 GHz bandwidth, and integrated RSSI functionality, operating from a single 3.3 V supply with 100 mW typical power dissipation.

For engineers reviewing the ONET8531TYS9 datasheet, ONET8531TYS9 pinout, ONET8531TYS9 application, or ONET8531TYS9 equivalent, key selection criteria include input overload current (2.5 mA_p-p), CML output termination (on-chip 50 Ω to VCC), die-level packaging for TO-can integration, and RSSI output options for internal/external photodiode biasing.

Technical Context

The ONET8531TYS9 implements a three-stage signal path: a transimpedance amplifier with AGC-driven gain limiting, a voltage-limiting amplifier, and a CML output buffer with on-chip 50 Ω back-termination. Its dual supply architecture separates VCC_IN (for TIA) from VCC_OUT (for voltage/CML stages), enabling independent noise isolation.

It integrates on-die supply filtering via internal 220 Ω filter resistors and capacitors for PIN photodiode biasing, supports both internal (RSSI_IB) and external-bias (RSSI_EB) RSSI modes, and features DC offset cancellation using internal low-pass filters to maintain TIA linearity under varying photocurrent conditions.

Key Specifications

Pinout & Package

ONET8531TYS9 is supplied as a bare die (DIESALE package) with 19 bond pads, intended for integration into TO-can optical modules. The die thickness is 203 ±13 μm, and each pad measures 105 × 65 μm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX3748AETE+ and LMH6525MA/NOPB, ONET8531TYS9 uniquely combines 10 GHz bandwidth, on-die RSSI, AGC, and CML termination in a die form factor optimized for TO-can optical assembly - eliminating four external components versus typical discrete TIA designs.

Availability

ONET8531TYS9 is available at Aetrix Electronics and suitable for SFP+, 10G Ethernet, and SONET OC-192 optical receiver designs requiring stable component supply, high-volume die procurement, and long-term lifecycle support.

Supply support for ONET8531TYS9 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 for communications, industrial, and automotive markets.

The ONET8531TYS9 belongs to TI's ONET family of optical receiver ICs, engineered specifically for cost-sensitive, high-volume fiber-optic transceiver modules demanding low-power, high-bandwidth, and integrated diagnostics.

FAQ

What is the primary function of the ONET8531TYS9 in an optical receiver?

The ONET8531TYS9 serves as a limiting transimpedance amplifier that converts photodiode current into a clean, differential CML data output. It integrates automatic gain control (AGC), received signal strength indication (RSSI), and on-chip supply filtering - making it a complete analog front-end for 10.3125 Gbps optical receivers such as those used in SFP+ modules. Its design eliminates the need for external termination resistors or VCC bypass capacitors.

Does the ONET8531TYS9 support both PIN and APD photodiodes?

Yes, the ONET8531TYS9 supports both PIN and APD photodiodes through dual RSSI configurations: RSSI_IB is used when the photodiode is biased via the internal FILTER pins (typical for PIN diodes), while RSSI_EB is intended for externally biased photodiodes like APDs. The device's 2.5 mA_p-p input overload current and AGC ensure stable operation across wide photocurrent ranges encountered with either detector type.

What package form is the ONET8531TYS9 delivered in?

The ONET8531TYS9 is supplied as a bare die (DIESALE package) measuring 940 × 1195 μm, with 19 bond pads arranged for direct integration into TO-46 or similar hermetic optical cans. It is not offered in leaded or laminate packages. The die thickness is 203 ±13 μm, and each bond pad is 105 × 65 μm - optimized for wire bonding in high-frequency optical assemblies.

How does the ONET8531TYS9 handle power supply noise?

The ONET8531TYS9 achieves –15 dB power supply noise rejection (PSNR) below 10 MHz when implemented per SFF-8431 guidelines. This is enabled by its split-supply architecture (VCC_IN for TIA, VCC_OUT for output stages) and on-die filtering on both supply domains. The internal 220 Ω filter resistors and capacitors on FILTER1/FILTER2 further isolate photodiode bias from supply ripple, critical for maintaining low-jitter performance in noisy system environments.

Can the ONET8531TYS9 be used without connecting the RSSI outputs?

Yes, the ONET8531TYS9 operates fully without RSSI connections: RSSI_IB and RSSI_EB pads may be left open if signal strength monitoring is not required. However, if RSSI is unused while operating with internal photodiode bias (FILTER pins), the RSSI_IB pad must remain unconnected - floating - to avoid unintended current paths. No pull-up or pull-down is needed, and leaving it open has no impact on TIA or output performance.