Analog Devices Inc. LTC4266AIUHF-1#PBF

Overview

LTC4266AIUHF-1#PBF from Analog Devices is a quad-channel LTPoE++ Power Sourcing Equipment (PSE) controller delivering up to 38.7W per port across four independent Ethernet ports, featuring IEEE 802.3at Type 1/2 compliance, 14-bit current monitoring ADCs, 0.25Ω sense resistors, and I²C interface up to 1MHz - deployed in high-power PoE midspans and switches for IP cameras and wireless access points.

For engineers reviewing the LTC4266AIUHF-1#PBF datasheet, LTC4266AIUHF-1#PBF pinout, LTC4266AIUHF-1#PBF application, or LTC4266AIUHF-1#PBF equivalent, this page delivers verified specifications, real-world port-level timing behavior, LTPoE++ detection/classification logic, thermal-aware gate drive control, and interoperability details with legacy and high-power PDs - all grounded in the official Linear Technology (Analog Devices) datasheet Rev. DC-4266AC-FE.

Technical Context

The LTC4266AIUHF-1#PBF implements a proprietary dual-mode 4-point PD detection scheme (2-point forced voltage + 2-point forced current) with high-capacitance legacy device immunity, ensuring robust false-PD rejection. Its classification engine supports full IEEE 802.3af/at and LTPoE++ Class 0–4, with DAC-programmable current limits and automatic foldback during overvoltage conditions.

Each channel integrates a fast-pull-down gate driver (30mA sink), 14-bit port current/voltage readback (30.5µV/LSB and 5.835mV/LSB resolution), and independent shutdown control via SHDN1–SHDN4 pins or I²C registers. The device operates with a negative main supply (VEE = –45V to –57V) referenced to AGND and uses DGND-referenced digital logic.

Key Specifications

Pinout & Package

Package: 38-lead (5mm × 7mm) plastic QFN with exposed thermal pad connected to VEE (pin 39), requiring soldering to PCB for thermal management (θ_JA = 34°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-channel PoE PSE controller applications.

Compared with LTC4266AIUHF-2#PBF, the LTC4266AIUHF-1#PBF offers lower thermal stress and reduced MOSFET conduction loss at 38.7W, while MAX5984AEUI+T requires full firmware redesign and cannot support LTPoE++ PDs - making LTC4266AIUHF-1#PBF optimal for balanced high-power PoE systems needing interoperability and field-proven reliability.

Availability

LTC4266AIUHF-1#PBF is available at Aetrix Electronics and suitable for IP surveillance systems, enterprise wireless infrastructure, and industrial IoT gateways requiring stable component supply, long-term lifecycle support, and guaranteed LTPoE++ compliance.

Supply support for LTC4266AIUHF-1#PBF 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

Analog Devices (formerly Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving industrial, automotive, communications, and aerospace markets with precision, reliability, and innovation.

The LTC4266A product line was designed specifically for high-power, multi-port Power over Ethernet infrastructure - addressing the gap between IEEE 802.3at (25.5W) and emerging >30W applications through proprietary LTPoE++ detection, robust thermal management, and autonomous operation modes.

FAQ

What is the maximum power per port supported by the LTC4266AIUHF-1#PBF?

The LTC4266AIUHF-1#PBF supports up to 38.7W per port under LTPoE++ specification, as confirmed in the Order Information table (page 2 of datasheet Rev. DC-4266AC-FE). This rating assumes use of 0.25Ω sense resistors, –54V VEE supply, and proper thermal management via the exposed VEE pad. It is distinct from the 52.7W (LTC4266AIUHF-2#PBF) and 90W (LTC4266AIUHF-4#PBF) variants in the same family.

Does the LTC4266AIUHF-1#PBF support IEEE 802.3af and 802.3at compliant powered devices?

Yes, the LTC4266AIUHF-1#PBF fully supports IEEE 802.3af (Type 1, 13W) and 802.3at (Type 2, 25.5W) PDs while adding LTPoE++ extensions. Its proprietary 4-point detection ensures interoperability with legacy devices, and classification thresholds (e.g., 5.5–7.5mA for Class 0–1) match IEEE-defined ranges. No firmware or hardware modification is needed to support backward-compatible operation.

How does the AUTO pin function on the LTC4266AIUHF-1#PBF?

The AUTO pin on the LTC4266AIUHF-1#PBF enables autonomous PSE operation without an I²C host controller. When tied to VDD or DGND, it configures internal registers at power-up or reset to predefined states - allowing immediate detection, classification, and power application to PDs. Its real-time status is readable at bit 0 of the Pin Status register (11h), and it remains active even if the I²C bus is inactive.

What is the purpose of separate SDAIN and SDAOUT pins on the LTC4266AIUHF-1#PBF?

The LTC4266AIUHF-1#PBF uses separate SDAIN (input) and SDAOUT (open-drain output) pins to simplify opto-isolation of the I²C bus in high-noise industrial environments. This eliminates the need for bidirectional level translators or complex isolation circuitry. For standard non-isolated designs, SDAIN and SDAOUT are tied together externally, as specified in the Pin Functions section (page 14).

Can the LTC4266AIUHF-1#PBF be used in midspan PoE applications?

Yes, the LTC4266AIUHF-1#PBF supports midspan operation via the MID pin (pin 21). When pulled HIGH, the device enters midspan mode - adjusting detection timing (e.g., 2.3–2.7s midspan backoff timer) and disabling endpoint-specific features. This allows seamless integration into inline power injectors that add PoE capability to existing non-PoE network switches without modifying data path integrity.