Texas Instruments UCC24624DT

Overview

UCC24624 from Texas Instruments is a dual-channel synchronous rectifier (SR) controller optimized for LLC resonant converters, replacing output diodes with N-channel MOSFETs to improve efficiency. It features 23-ns turn-off delay, 230-V V_D pin rating, 4.25–26-V V_DD operation, proportional gate drive, and two-channel interlock-enabling high-frequency (up to 625 kHz), high-efficiency power supplies in server and industrial AC/DC systems.

For engineers reviewing the UCC24624 datasheet, UCC24624 pinout, UCC24624 application, or UCC24624 equivalent, key selection considerations include drain-sensing SR timing accuracy, adaptive blanking for DCM ring rejection, standby-mode current (180 µA), V_SS-based threshold adjustment, and SOIC-8 compatibility with high-voltage secondary-side placement.

Technical Context

The UCC24624 uses drain-to-source voltage (V_DS) sensing on both channels to trigger SR turn-on below –265 mV and turn-off above a programmable 10.5 mV threshold. Its internal 11-V linear regulator (powered from V_DD) supplies stable gate drive while supporting pass-through mode down to 4.25 V.

It integrates 475-ns on-time and 650-ns off-time blanking to suppress false triggering from parasitic ringing, plus adaptive turn-on delay and interlocked channel control to prevent shoot-through. Standby mode activates automatically below 9 kHz average switching frequency, reducing V_DD current to 180 µA.

Key Specifications

Pinout & Package

UCC24624 is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body size) with exposed pad not specified. The layout prioritizes short, non-overlapping traces for V_D1, V_D2, and V_SS to minimize parasitic inductance-induced sensing errors.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous rectifier controller applications.

Compared with UCC24624, UCC24612DR offers lower channel count and reduced feature set for simpler designs, while NCP4306A provides entry-level SR control without adaptive timing or ultra-low standby current-making UCC24624 the only option supporting high-efficiency, dual-channel, high-frequency LLC with programmable thresholds and automatic low-power mode.

Availability

UCC24624 is available at Aetrix Electronics and suitable for server power supplies, ATX desktop PSUs, and industrial AC/DC modules requiring stable component supply, long-lifecycle support, and compliance with energy efficiency standards including DoE Level VI and CoC Tier 2.

Supply support for UCC24624 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 power management technologies, with decades of expertise in high-efficiency power conversion ICs.

The UCC24624 belongs to TI's high-performance synchronous rectifier controller product line, designed specifically to maximize efficiency in resonant topologies-especially LLC converters-by combining precision V_DS sensing, adaptive timing, and robust dual-channel gate driving.

FAQ

What is the maximum LLC switching frequency supported by the UCC24624?

The UCC24624 supports LLC resonant converters operating up to 625 kHz. This capability is enabled by its 23-ns turn-off propagation delay and 475-ns minimum on-time blanking, which together ensure reliable SR timing even above resonant frequency where di/dt is highest. The UCC24624 datasheet confirms this limit under Recommended Operating Conditions (f_SW = 625 kHz max).

How does the UCC24624 achieve automatic standby mode without external components?

The UCC24624 implements automatic standby mode detection based on average switching frequency-entering standby when f_AVG falls below 9 kHz and waking when it exceeds 15.6 kHz. During standby, both VG outputs are actively held low and non-essential circuitry is disabled, reducing V_DD current to 180 µA. No external timer, microcontroller, or signal conditioning is required-the function is fully integrated within the UCC24624.

Can the UCC24624 be used with output voltages higher than 24.75 V?

Yes-the UCC24624 can operate with output voltages exceeding 24.75 V by leveraging its internal 27.5-V V_DD clamp. A series current-limiting resistor is added between the LLC output and the V_DD pin to restrict clamp current to <15 mA (e.g., ≥750 Ω for 36-V output). This preserves 11-V REG regulation and full gate-drive capability while relocating dissipation from the IC to the external resistor.

What is the purpose of the VSS pin on the UCC24624, and how is it used?

The VSS pin serves as the shared source reference for both SR channels' V_DS sensing. It enables precise turn-off threshold adjustment: adding a resistor between VSS and the MOSFET source pins injects offset current (typ. 330 µA), raising the effective turn-off threshold to counteract parasitic inductance-induced voltage spikes. Layout requires direct connection to both MOSFET sources and avoidance of shared power-path routing to maintain sensing integrity.

Does the UCC24624 support both N-channel and P-channel MOSFETs?

No-the UCC24624 is designed exclusively for N-channel MOSFETs. Its gate drivers (VG1/VG2) provide 1.5-A source and 4-A sink capability to drive N-channel devices in low-side configuration on the secondary side of LLC converters. The architecture relies on V_DS sensing relative to VSS and does not support high-side P-channel drive or level-shifting circuitry.