Analog Devices Inc. LTC4269CDKD-1#PBF

Overview

LTC4269CDKD-1#PBF from Analog Devices (formerly Linear Technology) is an IEEE 802.3at Type 2 Powered Device (PD) controller with integrated synchronous flyback regulator. It delivers up to 25.5W output, features a 0.7Ω integrated Hot Swap MOSFET, supports 2-event classification, and operates from 18V–60V input for VoIP phones and PTZ security cameras.

For engineers reviewing the LTC4269CDKD-1#PBF datasheet, LTC4269CDKD-1#PBF pinout, LTC4269CDKD-1#PBF application, or LTC4269CDKD-1#PBF equivalent, key selection criteria include PoE interface compliance, isolated flyback efficiency >92%, programmable class current via RCLASS, thermal/overvoltage protection, and DFN-32 package thermal performance.

Technical Context

The LTC4269CDKD-1#PBF integrates a current-mode synchronous flyback controller with patented No-Opto feedback, eliminating optocouplers while maintaining tight multi-rail regulation. Its state machine handles IEEE 802.3at 2-event classification and asserts T2P to signal Type 2 PSE presence.

It embeds a 100V-rated 0.7Ω Hot Swap MOSFET with inrush control, undervoltage lockout referenced to VPORTP (not VCC), and dual PWRGD outputs - one referenced to VNEG (active-high, 14V-clamped), one to VPORTN (active-low). Soft-start, switching frequency (100kHz typ), and minimum on-time are externally programmable.

Key Specifications

Pinout & Package

Package: 32-lead (7mm × 4mm) plastic DFN with exposed thermal pad (Pin 33) soldered to VNEG plane for enhanced thermal dissipation (θ_JA = 34°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Powered Device controller applications.

Compared with MAX5974CETJ+T and TPS23754PWPR, the LTC4269CDKD-1#PBF uniquely combines No-Opto isolation, integrated 0.7Ω Hot Swap FET, and dedicated T2P signaling - enabling compact, high-efficiency 25.5W PD designs without external complexity.

Availability

LTC4269CDKD-1#PBF is available at Aetrix Electronics and suitable for VoIP phones, wireless access points, PTZ security cameras, and RFID readers requiring stable component supply and full IEEE 802.3at compliance.

Supply support for LTC4269CDKD-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 acquired Linear Technology in 2017 and maintains its legacy of high-performance analog and power management ICs for demanding industrial and communications applications.

The LTC4269-1 product line delivers complete IEEE 802.3at Type 2 PD solutions with integrated Hot Swap, No-Opto flyback control, and classification intelligence - targeting space-constrained, thermally sensitive PoE-powered endpoints.

FAQ

What is the maximum power delivery capability of the LTC4269CDKD-1#PBF?

The LTC4269CDKD-1#PBF is IEEE 802.3at Type 2 compliant and supports up to 25.5W of delivered power at the PD input. Its integrated 0.7Ω Hot Swap MOSFET and synchronous flyback controller enable high-efficiency conversion, with isolated output efficiency exceeding 92% and >88% including diode bridge and FET losses. This makes the LTC4269CDKD-1#PBF suitable for power-hungry endpoints like PTZ cameras and dual-radio access points.

How does the LTC4269CDKD-1#PBF implement IEEE 802.3at 2-event classification?

The LTC4269CDKD-1#PBF implements 2-event classification through dedicated hardware logic and the T2P (Type 2 PSE) pin (Pin 2). After detecting a valid signature, it performs classification per IEEE 802.3at, and upon successful 2-event handshake, asserts T2P low. This signal informs the host microcontroller that a Type 2 PSE is present, enabling firmware to safely enable higher-power loads. The LTC4269CDKD-1#PBF also supports 1-event classification for backward compatibility with 802.3af systems.

What is the purpose of the No-Opto feedback architecture in the LTC4269CDKD-1#PBF?

The No-Opto feedback architecture in the LTC4269CDKD-1#PBF eliminates the need for an optocoupler in isolated flyback designs by using a third winding on the transformer to sense output voltage during the flyback period. This patented method provides full IEEE 802.3 isolation while reducing BOM cost, improving long-term reliability (no LED aging), and simplifying layout. The LTC4269CDKD-1#PBF's FB pin (Pin 16) interfaces directly with this sensing network to maintain tight regulation across multiple outputs.

Can the LTC4269CDKD-1#PBF operate with auxiliary power sources?

Yes, the LTC4269CDKD-1#PBF supports auxiliary power dominance via the SHDN (Shutdown) pin (Pin 1). Driving SHDN high disables the PD interface, corrupts the signature resistance below 11kΩ (invalidating IEEE detection), and disconnects the load from the PoE input. This allows seamless switchover to an external 5V or 12V supply. When unused, SHDN must be tied to VPORTN. The LTC4269CDKD-1#PBF's VCC UVLO and wide 18V–60V input range further enhance auxiliary power flexibility.

What thermal management features does the LTC4269CDKD-1#PBF include?

The LTC4269CDKD-1#PBF includes thermal shutdown protection and a thermally enhanced 7mm × 4mm DFN package with an exposed pad (Pin 33) that must be soldered to a VNEG-connected heat sinking plane. Its θ_JA is 34°C/W and θ_JC is just 2°C/W, enabling high-power operation in compact enclosures. Internal thermal monitoring disables the Hot Swap FET if junction temperature exceeds 125°C (T_JMAX). The LTC4269CDKD-1#PBF's low 0.7Ω R_DS(on) further minimizes self-heating under full 25.5W load.