Broadcom Limited AFBR-734TMZ

Overview

AFBR-734TMZ from Broadcom is a 25GbE SFP28 optical transceiver with 850-nm VCSEL transmitter and PIN photodiode receiver, supporting 25.78 Gb/s serial line rate over multi-mode fiber per IEEE 802.3by 25GBASE-SR. It integrates dual CDR circuits (Tx and Rx), real-time digital diagnostics per SFF-8472, and operates at 3.3V within 0°C to 70°C case temperature. It delivers high-sensitivity operation enabling FEC-free links up to 50 m on OM4 fiber.

For engineers reviewing the AFBR-734TMZ datasheet, pinout, applications, or equivalent options, this page provides verified technical context for 25GBASE-SR system integration-including CDR lock behavior, SFF-8419 two-wire interface timing, OM4/OM3 link distance validation, diagnostic accuracy specs, and SFP28 mechanical compliance per SFF-8432.

Technical Context

The AFBR-734TMZ implements fixed-rate, non-bypassable CDRs on both Tx and Rx paths, locking exclusively at 25.78125 Gb/s ±100 ppm per IEEE 802.3by. Its transmitter uses an 850-nm VCSEL with integral light monitoring and imaging optics coupled to an LC duplex connector; receiver employs a high-speed PIN detector with post-amplification and variable emphasis control.

Digital diagnostics are implemented via SFF-8472-compliant two-wire serial interface (MOD_SCL/MOD_SDA) with host-accessible real-time monitoring of Tx power (–8.4 to +2.4 dBm), Rx power (–10.3 to +2.4 dBm), temperature (±3.0°C accuracy), supply voltage (±0.1 V), and laser bias current (±10% accuracy). All low-speed control signals-TX_DISABLE, TX_FAULT, RX_LOS-are open-drain with defined pull-up/pull-down requirements per SFF-8419.

Key Specifications

Pinout & Package

SFP28 form factor per SFF-8432: 20-pin edge connector, LC duplex optical interface, 3.3V single supply, RoHS-compliant package with Class 1 laser safety certification (IEC60825-1/CDRH).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 25GBASE-SR optical transceiver applications.

Compared with FTLF8528P2BNV and OPF2822-NC, the AFBR-734TMZ offers tighter optical power measurement accuracy (±3.0 dB), integrated variable Tx EQ for host board margin recovery, and optimized power efficiency (≤1.0 W), making it preferred for high-density, thermally constrained 25GbE switch ports.

Availability

AFBR-734TMZ is available at Aetrix Electronics and suitable for Ethernet switch port interconnects, server NIC aggregation, inter-chassis link extension, and blade server fabric interconnects requiring stable component supply, full SFF-8472 diagnostic support, and guaranteed 25GBASE-SR compliance.

Supply support for AFBR-734TMZ 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

Broadcom Inc. is a global leader in semiconductor and infrastructure software solutions, specializing in high-performance connectivity, networking, and broadband technologies.

The AFBR-734TMZ belongs to Broadcom's SFP28 optical transceiver product line, engineered specifically for low-latency, high-reliability 25GbE data center and enterprise switching applications with integrated diagnostics and strict IEEE/SFF compliance.

FAQ

Does the AFBR-734TMZ support bypassing its internal CDR circuits?

No, the AFBR-734TMZ does not support CDR bypass. As mandated by IEEE 802.3by, both transmitter and receiver CDR circuits are permanently engaged and lock exclusively at 25.78125 Gb/s ±100 ppm. The rate select pins (RS(0)/RS(1)) are unused and internally pulled down; no configuration or host command can disable or reconfigure the CDR functionality in the AFBR-734TMZ.

What is the maximum supported link distance for AFBR-734TMZ on OM4 fiber with FEC disabled?

The AFBR-734TMZ supports up to 50 meters on OM4 multi-mode fiber at a bit error rate of 1E–12 without forward error correction (FEC). This high-sensitivity performance is validated per IEEE 802.3by Clause 112 and confirmed in Table 4 of the AFBR-734TMZ-DS100 datasheet under "Fiber Length (OM4), 1E–12 BER". The transceiver achieves this using optimized VCSEL drive and receiver sensitivity design.

How accurate is the real-time optical power monitoring in AFBR-734TMZ?

The AFBR-734TMZ provides ±3.0 dB accuracy for both transmitted average optical power (PT) and received optical input power (PR), as specified in Table 12 of the datasheet. This accuracy is valid across the full operational range: PT from –8.4 dBm to +2.4 dBm, and PR from –10.3 dBm to +2.4 dBm, when coupled into 50-µm multi-mode fiber. Calibration is performed internally and reported via SFF-8472 DMI registers.

What are the host board requirements for MOD_SCL and MOD_SDA signals of AFBR-734TMZ?

The MOD_SCL and MOD_SDA pins of the AFBR-734TMZ require external 4.7 kΩ to 10 kΩ pull-up resistors to the host's 3.3 V supply (3.14–3.46 V), as stated in Table 2 note c. The interface supports up to 400 kHz clock rate with up to 500 µs clock stretching per SFF-8419. No series termination or AC coupling is needed - the transceiver handles all signal conditioning internally.

Is AFBR-734TMZ compatible with legacy SFP+ host systems?

No, the AFBR-734TMZ is not interoperable with standard SFP+ hosts. It is an SFP28-compliant device per SFF-8432 and requires a host system that supports 25 Gb/s signaling, SFF-8419 low-speed interface timing, and 25GBASE-SR-specific CDR and diagnostic register maps. Attempting to plug the AFBR-734TMZ into an SFP+-only slot may result in failure to initialize or undefined behavior due to incompatible electrical and protocol requirements.