Analog Devices Inc. LT3952EFE#TRPBF

Overview

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

For engineers reviewing the LT3952EFE#TRPBF datasheet, LT3952EFE#TRPBF pinout, LT3952EFE#TRPBF application, or LT3952EFE#TRPBF equivalent, key selection criteria include its 4 A peak switch current rating, SSFM-enabled EMI reduction (±31% unidirectional frequency sweep), 100 kHz to 1 MHz programmable f_SW, RAMP-pin-based modulation control, and thermal shutdown with hysteresis.

Technical Context

The LT3952EFE#TRPBF 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 multiple DC-DC configurations. Its oscillator supports precise RT-resistor programming and integrates a dedicated RAMP pin for triangle-wave injection to enable SSFM.

SSFM operates via pseudo-random frequency stepping from nominal f_SW to +31% in 1% increments at a hop rate of f_SW/32, avoiding narrowband interference (e.g., AM radio band) without introducing periodic ripple. The device includes analog current sense with ±3% accuracy, soft-start, and open/short LED fault protection.

Key Specifications

Pinout & Package

LT3952EFE#TRPBF is housed in a 28-lead TSSOP package with exposed pad (EFE), 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 switch current.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3795EFE#TRPBF and LT8390AIFE#TRPBF, the LT3952EFE#TRPBF uniquely combines 42 V input, integrated 4 A switch, and pseudo-random SSFM across five topologies-making it optimal for cost-sensitive, space-constrained automotive and industrial LED systems requiring EMI certification.

Availability

LT3952EFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp modules, industrial high-bay luminaires, and architectural LED signage requiring stable component supply, long-term lifecycle support, and full traceability.

Supply support for LT3952EFE#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, headquartered in Norwood, MA, with design centers and manufacturing worldwide.

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

FAQ

What is the maximum output voltage supported by the LT3952EFE#TRPBF?

The LT3952EFE#TRPBF supports up to 60 V output voltage in boost, buck-boost, SEPIC, and flyback configurations. This rating is defined by its internal 60 V power switch breakdown voltage and is validated across temperature and process corners. Exceeding 60 V risks permanent damage to the integrated MOSFET. The LT3952EFE#TRPBF does not support output voltages above this limit even with external components.

How does SSFM work in the LT3952EFE#TRPBF, and what capacitor value should I use on the RAMP pin?

The LT3952EFE#TRPBF implements pseudo-random SSFM with a hop rate of f_SW/32 and a +0% to +31% frequency sweep. A capacitor on the RAMP pin sets the modulation frequency; 6.8 nF yields ~1 kHz, which is recommended for initial peak EMI testing. Values between 4.7 nF and 10 nF allow fine-tuning to suppress specific interference bands observed during pre-compliance scans. The LT3952EFE#TRPBF requires no external triangle generator-the internal circuitry produces the waveform automatically.

Can the LT3952EFE#TRPBF operate in buck topology with an input voltage higher than the LED string voltage?

Yes, the LT3952EFE#TRPBF fully supports buck topology when the input voltage exceeds the forward voltage of the LED string. In this mode, it regulates LED current using high-side current sensing and internal PWM control. The device maintains ±3% current accuracy from 10% to 100% load and includes built-in slope compensation for stable operation at duty cycles above 50%. The LT3952EFE#TRPBF's buck implementation requires no external components beyond the inductor, diode, and sense resistor.

What thermal considerations apply to the LT3952EFE#TRPBF in continuous 4 A operation?

The LT3952EFE#TRPBF's 28-lead TSSOP-EFE package requires the exposed pad to be soldered to a minimum 200 mm² copper area connected to ground for thermal conduction. At 4 A continuous switch current and 42 V input, junction temperature must remain below 125°C. With 4-layer PCB, 2 oz copper, and 200 mm² thermal pad, typical θ_JA is 42°C/W. Derating is required above 85°C ambient; the LT3952EFE#TRPBF includes thermal shutdown with 20°C hysteresis to protect against sustained overload.

Does the LT3952EFE#TRPBF support PWM dimming, and how is it implemented?

Yes, the LT3952EFE#TRPBF supports true PWM dimming via its CTRL pin, which accepts 0–1.25 V analog control or 100 Hz–20 kHz digital PWM signals. When driven with PWM, the IC rapidly enables/disables the power switch to achieve dimming ratios up to 10,000:1 without color shift. The LT3952EFE#TRPBF also supports analog dimming through the CTRL pin (0–1.25 V) for smooth 10:1 brightness control. Both methods preserve constant-current regulation during active periods.