Analog Devices Inc. LT3952EFE#PBF

Overview

LT3952EFE#PBF from Analog Devices is a 42 V input, 60 V/4 A constant-current/constant-voltage multitopology LED driver IC with integrated 60 V DMOS power switch, pseudo-random spread spectrum frequency modulation (SSFM), and programmable oscillator via RT pin. It supports boost, buck-boost, SEPIC, and flyback topologies for high-brightness LED lighting in automotive, industrial, and signage applications.

For engineers reviewing the LT3952EFE#PBF datasheet, LT3952EFE#PBF pinout, LT3952EFE#PBF application, or LT3952EFE#PBF equivalent, this device delivers EMI reduction through unidirectional ±31% pseudo-random SSFM at f_SW/32 hop rate, 1% step resolution, and RAMP-pin-based modulation control - critical for CISPR-compliant LED systems operating across 100 kHz–30 MHz bands.

Technical Context

The LT3952EFE#PBF implements a current-mode PWM controller with internal 60 V, 4 A power switch, enabling direct drive of LED strings up to 60 V in boost or buck-boost configurations. Its oscillator supports precise RT-resistor programming (100 kHz–1 MHz nominal) and real-time pseudo-random frequency dithering.

SSFM operates by stepping the switching frequency upward from f_SW in discrete 1% increments up to +31%, updated at f_SW/32 rate, avoiding sensitive bands like AM radio (530–1710 kHz) without requiring external clock sources or phase-locked loops.

Key Specifications

Pinout & Package

LT3952EFE#PBF is housed in a 28-lead TSSOP package with exposed pad (EFE suffix), optimized for thermal dissipation in high-current LED driver applications. The exposed pad must be soldered to PCB ground plane for safe operation at full 4 A load.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver applications.

Compared with LT3795EFE#PBF and LM3409QMH/NOPB, the LT3952EFE#PBF uniquely combines integrated 60 V/4 A switching, unidirectional pseudo-random SSFM, and multitopology support - delivering faster time-to-compliance, lower thermal footprint, and fewer external components for 42 V-input LED systems.

Availability

LT3952EFE#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay fixtures, outdoor digital signage, and architectural accent lighting requiring stable component supply and guaranteed long-term availability.

Supply support for LT3952EFE#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The LT3952EFE#PBF belongs to Analog Devices' Power by Linear™ LED driver product line, engineered specifically for high-reliability, low-EMI solid-state lighting in automotive, industrial, and infrastructure applications.

FAQ

What is the maximum output current capability of the LT3952EFE#PBF?

The LT3952EFE#PBF integrates a 60 V, 4 A DMOS power switch and is specified for continuous 4 A LED current in boost and buck-boost topologies. At ambient temperatures ≤55°C with proper PCB copper area (≥4 cm² thermal pad), it sustains full 4 A output; derating applies above that temperature per the thermal resistance curve in the official LT3952 datasheet. The LT3952EFE#PBF achieves this without external FETs or gate drivers.

How does the SSFM function in the LT3952EFE#PBF differ from standard triangle-wave modulation?

Unlike triangle-wave SSFM (e.g., in LT8609), the LT3952EFE#PBF uses pseudo-random stepping - frequency increases in fixed 1% increments from f_SW to +31%, updated at f_SW/32 rate. This avoids periodic ripple and associated audio/display artifacts. The LT3952EFE#PBF's unidirectional method also allows intentional placement above sensitive bands (e.g., AM radio), confirmed in Figure 10 of the Analog Devices technical article.

Which topologies does the LT3952EFE#PBF support, and what external components define them?

The LT3952EFE#PBF supports boost, buck-boost, SEPIC, and flyback topologies. Topology is determined by external component configuration: boost uses single inductor and diode; buck-boost adds coupling capacitor; SEPIC replaces diode with second inductor; flyback substitutes transformer for inductor. All share identical LT3952EFE#PBF pin connections and feedback network - only passive layout changes are needed.

Can the LT3952EFE#PBF operate without the RAMP capacitor, and what is the impact?

Yes, the LT3952EFE#PBF operates in fixed-frequency mode when the RAMP pin is left open or tied to ground - SSFM is disabled. In this state, the LT3952EFE#PBF delivers standard PWM regulation with no frequency dither. EMI performance reverts to narrowband peaks; average and peak conducted emissions increase significantly, as shown in Figures 8 and 9 of the Analog Devices SSFM technical article.

What thermal management requirements apply to the LT3952EFE#PBF in 4 A operation?

The LT3952EFE#PBF requires its exposed pad soldered to ≥4 cm² of inner-layer copper connected to system ground. With 2 oz copper and 4 thermal vias (0.3 mm diameter), junction-to-ambient θ_JA is ~40°C/W. At 4 A/36 V output, power dissipation reaches ~2.5 W; this yields ~100°C junction rise above 25°C ambient - within the 125°C max rating. The LT3952EFE#PBF includes thermal shutdown at 165°C for protection.