Texas Instruments ONET8541TY

Overview

ONET8541TY 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. It operates from a single 3.3 V ±10% supply and dissipates 90 mW typical power in die form for TO-can packaging.

For engineers reviewing the ONET8541TY datasheet, ONET8541TY pinout, ONET8541TY application, or ONET8541TY equivalent, this device serves as a high-speed photodiode front-end in 10G Ethernet, Fibre Channel, and EPON systems-where low-noise amplification, deterministic jitter control (<16 ps_PP), and on-chip photodiode bias filtering are critical selection criteria.

Technical Context

The ONET8541TY implements a three-stage signal path: a transimpedance amplifier with AGC-driven gain reduction above ~250 µA_PP, a limiting voltage amplifier, and a CML output buffer with on-chip 50 Ω back-termination to V_CC. Its dual-supply architecture isolates V_{CC_IN} (TIA stage) from V_{CC_OUT} (voltage/CML stages) to suppress supply coupling.

It integrates photodiode bias filtering via internal 220 Ω resistors and on-die capacitors at FILTER1/FILTER2 pins, enabling low-pass corner <5 MHz for PIN diodes. The RSSI circuitry provides two current-mode outputs-RSSI_IB for internally biased receivers and RSSI_EB for externally biased APD/PIN configurations-with gain accuracy of ±2% and offset current ≤16 µA (no-light condition).

Key Specifications

Pinout & Package

ONET8541TY is supplied in die form (DIESALE package), sized 870 µm × 1036 µm, optimized for TO-can assembly with ground-signal-ground (GSG) photodiode layouts. Bond pad pitch is standardized for wire bonding; die thickness is 203 ± 13 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, ONET8541TY delivers superior integration (on-chip RSSI, photodiode bias filter, 50 Ω termination) and lower power (90 mW vs. ≥145 mW), making it optimal for space- and thermal-constrained TO-can optical modules targeting 10G standards with built-in diagnostics.

Availability

ONET8541TY is available at Aetrix Electronics and suitable for 10G Ethernet, Fibre Channel, and EPON optical receiver designs requiring stable component supply, long-term lifecycle continuity, and traceable sourcing for production deployment.

Supply support for ONET8541TY 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 specializing in analog, embedded processing, and connectivity technologies, with leadership in high-speed optical interface solutions.

The ONET8541TY belongs to TI's ONET family of optical networking ICs, designed specifically for next-generation fiber-optic receiver front-ends requiring high sensitivity, low jitter, and integrated diagnostics in compact packages.

FAQ

What is the operating temperature range for the ONET8541TY?

The ONET8541TY is characterized for operation from –40°C to +100°C case temperature (measured at the IC back side). This range supports deployment in industrial and telecom environments including outdoor ONU enclosures and central office line cards. Thermal derating is not required within this specification, and all key parameters-including transimpedance, bandwidth, and RSSI gain-are guaranteed across the full range.

Does the ONET8541TY require external supply decoupling capacitors?

No, the ONET8541TY integrates on-chip supply filter capacitors for both VCC_IN and VCC_OUT rails, eliminating the need for external bypass capacitors. However, TI recommends adding a 0.1 µF ceramic capacitor close to the VCC_OUT and VCC_IN pads if board-level noise exceeds –15 dB PSNR, particularly in multi-channel modules sharing common power planes.

How does the RSSI functionality differ between RSSI_IB and RSSI_EB on the ONET8541TY?

RSSI_IB is intended for use when the photodiode is biased from the ONET8541TY's internal FILTER1/FILTER2 nodes; it mirrors the photodiode current with 0.5 A/A gain. RSSI_EB is used when an external bias source (e.g., APD high-voltage supply) is employed, offering 0.6 A/A gain and optimized for accuracy under externally regulated conditions. Both outputs require an external load resistor to GND, with voltage constrained to ≤ VCC – 0.65 V.

Can the ONET8541TY be used with avalanche photodiodes (APDs)?

Yes-the ONET8541TY supports APD-based receivers via the RSSI_EB pin and external photodiode biasing. While its TIA input stage is optimized for PIN diodes (2.5 mAPP overload), the AGC and RSSI circuits remain functional with APD current outputs. Designers must ensure external APD bias circuitry provides stable voltage and low-noise operation, as the ONET8541TY does not generate high-voltage bias.

What is the recommended photodiode capacitance and bond-wire inductance for achieving the specified 9 GHz bandwidth?

To achieve the rated 9 GHz small-signal bandwidth, TI specifies 0.2 pF photodiode capacitance and 0.3 nH total bond-wire inductance (including both IN and GND paths). Layout best practices include minimizing IN pad capacitance, placing the photodiode adjacent to the die, and using symmetric, short bond wires-deviations beyond ±0.1 pF or ±0.1 nH degrade bandwidth and increase deterministic jitter.