Analog Devices Inc. LT3752EFE#PBF

Overview

LT3752EFE#PBF from Analog Devices is a current-mode PWM controller optimized for active clamp forward converter topologies, featuring integrated housekeeping DC/DC control, programmable volt-second clamp (DVSEC), and synchronous rectification support. It operates from 6.5V to 100V input, delivers up to 150W in isolated designs, and enables >50% primary duty cycle for high transformer utilization in telecom and industrial power supplies.

For engineers reviewing the LT3752EFE#PBF datasheet, LT3752EFE#PBF pinout, LT3752EFE#PBF application, or LT3752EFE#PBF equivalent, key selection criteria include its dual-loop control architecture (forward + housekeeping), active clamp timing programmability (tAO/tOA/tSO/tOS), 100–500kHz switching frequency range, and AEC-Q100 qualification for automotive isolated supplies.

Technical Context

The LT3752EFE#PBF implements a dual-controller architecture: a main forward controller with adaptive leading-edge blanking, programmable DVSEC clamp, and three independent gate drivers (OUT, AOUT, SOUT) for primary switch, active clamp MOSFET, and synchronous rectifier; plus a dedicated housekeeping controller with HFB/HCOMP pins, internal soft-start (2.2–4ms), and hiccup-mode overcurrent protection.

Its control logic supports both LO-side active clamp (LT3752) and HI-side active clamp (LT3752-1) topologies, with precise timing delays (e.g., tSO = tAO – tAS) set via external resistors (RTAO, RTAS, RTOS) and validated across –40°C to 125°C junction temperature. The INTVCC linear regulator provides 7.0V ±0.2V at up to 50mA for internal circuitry.

Key Specifications

Pinout & Package

The LT3752EFE#PBF is housed in a 38-lead plastic TSSOP package (FE38 variation) with missing pins for high-voltage spacing; exposed pad (Pin 39) is connected to PGND/GND and must be soldered to PCB for thermal and electrical integrity (θJA = 25°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar active clamp forward controller applications.

Compared with UCC2897A and MAX17596, the LT3752EFE#PBF uniquely integrates housekeeping regulation, supports 100V input, and enables programmable >50% duty cycle via DVSEC-critical for high-efficiency, high-power-density active clamp forward converters in telecom and automotive isolation.

Availability

LT3752EFE#PBF is available at Aetrix Electronics and suitable for telecom isolated power supplies, automotive battery-fed isolation, and industrial HV DC-DC conversion requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.

Supply support for LT3752EFE#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 (now part of Analog Devices, Inc., formerly Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving industrial, automotive, communications, and aerospace markets.

The LT3752 product line was designed specifically for high-efficiency active clamp forward converters in isolated power applications, emphasizing integration of housekeeping control, precise timing, and rugged operation across –40°C to +125°C.

FAQ

What is the maximum input voltage supported by the LT3752EFE#PBF?

The LT3752EFE#PBF supports an operational input voltage range of 6.5V to 100V, with an absolute maximum rating of 100V on the VIN pin. This enables direct connection to 48V and 72V industrial and telecom buses without external pre-regulation, as confirmed in the Absolute Maximum Ratings table (Rev. C, p.3) and Electrical Characteristics (p.4).

Does the LT3752EFE#PBF include an integrated auxiliary power supply?

Yes, the LT3752EFE#PBF includes a dedicated housekeeping DC/DC controller with HFB and HCOMP pins, providing independent regulation of an auxiliary output rail. Its 1.000V reference, PGOOD monitoring (0.92V/0.96V thresholds), and hiccup-mode overcurrent protection eliminate the need for an external bias supply, as detailed in the Housekeeping Controller section (pp.24–27) and Electrical Characteristics (p.7).

How is synchronous rectifier timing controlled in the LT3752EFE#PBF?

The LT3752EFE#PBF uses the SOUT pin to drive the secondary-side synchronous rectifier, with precise timing delays (tSO and tOS) programmable via external resistors RTAS and RTOS. Typical values range from 70ns to 164ns depending on resistor choice, ensuring zero-voltage switching and minimizing body diode conduction loss, as specified in the Electrical Characteristics table (p.6) and Applications Information (p.35).

What is the purpose of the DVSEC (volt-second clamp) function in the LT3752EFE#PBF?

The DVSEC function in the LT3752EFE#PBF programmably limits the volt-second product applied to the main transformer, enabling primary switch duty cycles above 50% while ensuring safe reset. At UVLO_VSEC = 2.50V and RT = 24.9kΩ, it achieves 36.5% max duty cycle-critical for high-power-density designs where transformer utilization directly impacts size and efficiency (Electrical Characteristics, p.7).

Is the LT3752EFE#PBF qualified for automotive applications?

Yes, the LT3752EFE#PBF is AEC-Q100 qualified for automotive applications (Grade 1: –40°C to +125°C), as explicitly stated in the Features list (p.1) and Order Information table (p.3). It supports micropower start-up (265µA max), wide input range (6.5V–100V), and robust protection features required for automotive isolated power supplies.