Analog Devices Inc. LT3752MPFE-1#TRPBF

Overview

LT3752MPFE-1#TRPBF from Analog Devices is a high-voltage active clamp synchronous forward controller IC optimized for isolated DC/DC power supplies with input voltages >100V, featuring programmable volt-second clamp (DVSEC), 100–500kHz switching frequency, and integrated housekeeping DC/DC controller. It enables >50% primary duty cycle, reduces switch voltage stress via active clamp topology, and supports synchronous rectification control for high-efficiency (>94%) 12V/12.5A isolated converters in automotive and industrial systems.

For engineers reviewing the LT3752MPFE-1#TRPBF datasheet, LT3752MPFE-1#TRPBF pinout, LT3752MPFE-1#TRPBF application, or LT3752MPFE-1#TRPBF equivalent, key selection criteria include its –55°C to 150°C extended temperature rating, HI-side active clamp topology support, INTVCC regulation at 9.4–10.4V, UVLO threshold of 9.5–10.4V (ON) with 1.61–2.19V hysteresis, and AEC-Q100 qualification for automotive use.

Technical Context

The LT3752MPFE-1#TRPBF implements dual-loop control: a main forward controller with current-mode PWM, adaptive leading-edge blanking, and programmable tAO/tOA delays for HI-side active clamp MOSFET timing; and an independent housekeeping controller with HFB reference (0.90–1.10V), HOUT driver, and hiccup-mode overcurrent protection. Its architecture separates primary-side power switching (OUT/AOUT) from secondary-side synchronous rectification (SOUT) with precise, independently programmable edge delays (tSO/tOS).

It operates with VIN >100V (limited only by external components), uses a 38-lead TSSOP package with missing pins for HV spacing, and integrates a 9.4–10.4V linear regulator (INTVCC) with 7–7.4V UVLO(+) and 15.4–17.2V OVLO(–)/(+). The device supports external clock synchronization, soft-start/stop via SS1/SS2, and open-loop DVSEC clamp control without optocoupler feedback.

Key Specifications

Pinout & Package

The LT3752MPFE-1#TRPBF is housed in a 38-lead plastic TSSOP (FE package, variation FE38(31)) with exposed pad (Pin 39) soldered to PGND/GND for thermal and electrical integrity. High-voltage spacing is achieved via missing pins (NC) at positions 25, 27, 29, 31, 33, 35.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3752HFE-1#TRPBF, the LT3752MPFE-1#TRPBF adds –55°C startup capability and AEC-Q100 qualification, making it uniquely suited for automotive cold-cranking and military low-temp deployments; versus UCC28950PWPR, it offers topology-specific integration (active clamp forward + housekeeping) but lower maximum power scalability.

Availability

LT3752MPFE-1#TRPBF is available at Aetrix Electronics and suitable for automotive 48V/100V battery systems, industrial isolated auxiliary power supplies, and ruggedized military DC/DC modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT3752MPFE-1#TRPBF 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LT3752/LT3752-1 product line was designed specifically for high-efficiency, high-reliability active clamp forward converters in automotive and industrial isolated power applications, emphasizing integrated housekeeping regulation, precise timing control, and extended temperature operation.

FAQ

What is the maximum input voltage supported by the LT3752MPFE-1#TRPBF?

The LT3752MPFE-1#TRPBF has no internal VIN voltage limit - its operational input voltage is "limited only by external components" per the datasheet. While absolute maximum rating is 16V on the VIN pin itself, the device is architected for >100V system inputs using external high-voltage FETs and proper gate drive isolation. Designers must ensure external components (MOSFETs, snubbers, transformers) are rated accordingly. The LT3752MPFE-1#TRPBF's UVLO and INTVCC regulator are optimized for this high-input regime.

Does the LT3752MPFE-1#TRPBF support both HI-side and LO-side active clamp topologies?

No - the LT3752MPFE-1#TRPBF is specifically the -1 variant, which supports HI-side active clamp topology using an external NMOS clamp switch driven by the AOUT pin. The standard LT3752 (non-1) supports LO-side clamp with PMOS. This distinction is hardwired in the internal driver architecture and cannot be reconfigured. Using LT3752MPFE-1#TRPBF with a LO-side clamp will result in incorrect timing and potential shoot-through.

How does the DVSEC volt-second clamp function in the LT3752MPFE-1#TRPBF?

The DVSEC clamp in the LT3752MPFE-1#TRPBF is programmed via the UVLO_VSEC pin voltage (0.2–0.6V micropower threshold, 1.18–1.32V system UVLO). At a given UVLO_VSEC voltage (e.g., 2.5V), the device calculates and enforces a maximum duty cycle (e.g., 36.5% at 100V input) to maintain transformer volt-second balance. This is implemented in hardware without optocoupler or error amplifier feedback, enabling simple open-loop clamp control - a core feature of the LT3752MPFE-1#TRPBF.

Is the LT3752MPFE-1#TRPBF pin-compatible with other LT3752 variants?

Yes - all LT3752 and LT3752-1 variants (EFE, IFE, HFE, MPFE) share identical 38-lead TSSOP pinouts and footprint, including LT3752MPFE-1#TRPBF. However, functional differences exist: the -1 suffix denotes HI-side clamp support, and MP grade adds –55°C to 150°C operation and AEC-Q100 qualification. Electrical parameters (UVLO thresholds, INTVCC voltage) differ between -1 and non--1 versions, so direct substitution requires validation of timing and bias conditions.

What is the role of the housekeeping controller in the LT3752MPFE-1#TRPBF?

The housekeeping controller in the LT3752MPFE-1#TRPBF is a fully integrated DC/DC regulator that generates an auxiliary output rail (via HOUT) using the same transformer winding as the main output. It features its own error amplifier (HFB/HCOMP), current sensing (HISENSE), soft-start (HSS), and hiccup-mode OCP. This eliminates the need for a separate bias supply, reducing system cost and complexity - a defining capability of the LT3752MPFE-1#TRPBF in isolated forward designs.