Analog Devices Inc. LT3965EFE-1#TRPBF

Overview

LT3965EFE-1#TRPBF from Analog Devices is an 8-channel automotive-grade LED bypass switch IC for individual PWM dimming of LEDs in high-voltage strings using a common current source. It integrates eight 17V/330mΩ NMOS switches, supports I²C multidrop (16-device bus), provides programmable open/shorted LED fault detection, and features fade-enabled 11-bit logarithmic dimming transitions. It is used in adaptive automotive headlight clusters requiring flicker-free, channel-isolated brightness control.

For engineers reviewing the LT3965EFE-1#TRPBF datasheet, LT3965EFE-1#TRPBF pinout, LT3965EFE-1#TRPBF application, or LT3965EFE-1#TRPBF equivalent, key selection criteria include VIN operating range (8–60V), per-channel fault threshold configurability (VOTH/VSTH), fade transition timing vs. RTCLK resistor value, and AEC-Q100 qualification for under-hood deployment.

Technical Context

The LT3965EFE-1#TRPBF implements a floating-source NMOS switch matrix architecture where each DRN/SRC pair operates independently with crowbar protection (22–25V clamp) and fast transition (0.35–0.65µs). Its I²C interface uses VDD-scaled logic (2.7–5.5V) and supports both SCM and ACM modes via ADDR[4:1]–configured 7-bit addresses (010xxxx0/1 or 101xxxx0/1).

Power-on reset initializes all eight switches ON (LEDs off), with default open LED threshold VOTH[1:0]="01" (8.5–9.5V) and shorted LED threshold VSTH[1:0]="00" (0.85–1.15V at LEDREF=0V). PWM dimming frequency is derived by dividing RTCLK input (internal oscillator or external clock) by 2048 - e.g., 28kΩ sets ~500Hz nominal dimming.

Key Specifications

Pinout & Package

LT3965EFE-1#TRPBF is housed in a 28-lead plastic TSSOP package (FE) with exposed pad (Pin 29 = GND) requiring PCB soldering for thermal and electrical integrity. θJC = 10°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3965EFE-1#TRPBF, LT3965EFE#TRPBF offers inverted startup behavior and higher open-LED threshold, while MAX20052ATP/V+T trades fade capability and voltage range for integrated sensing and SPI simplicity - making LT3965EFE-1#TRPBF optimal for high-VIN, fade-critical automotive exterior lighting.

Availability

LT3965EFE-1#TRPBF is available at Aetrix Electronics and suitable for automotive headlight clusters, large LED video displays, and automated camera flash equipment requiring stable component supply, AEC-Q100 compliance, and long-lifecycle support.

Supply support for LT3965EFE-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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision, power, and connectivity applications.

The LT3965/LT3965-1 product line was designed specifically for automotive and industrial LED matrix control, delivering robust fault management, flicker-free dimming, and scalable I²C architecture for high-reliability lighting systems.

FAQ

What is the default power-on behavior of the LT3965EFE-1#TRPBF?

The LT3965EFE-1#TRPBF powers up with all eight NMOS switches ON (bypassing LEDs, so LEDs are off), VOTH[1:0] set to "01" (8.5–9.5V open LED threshold), and VSTH[1:0] set to "00" (0.85–1.15V shorted LED threshold at LEDREF=0V). This POR state ensures fail-safe default operation in automotive lighting where initial dark state is preferred.

How does the RTCLK pin affect PWM dimming frequency in the LT3965EFE-1#TRPBF?

In the LT3965EFE-1#TRPBF, PWM dimming frequency equals the RTCLK input frequency divided by 2048. With an internal oscillator, a 28kΩ resistor to GND yields ~500Hz nominal dimming; with an external 1MHz clock, dimming frequency is 488Hz. The RTCLK pin must never be left floating - it must be either resistor-terminated or actively driven.

Can the LT3965EFE-1#TRPBF detect shorted LEDs in multi-LED segments?

Yes - the LT3965EFE-1#TRPBF detects shorted LEDs by comparing the voltage at DRN relative to SRC against the VSTH threshold. When LEDREF is set to 3V, VSTH can be programmed to 1V, 4V, 7V, or 10V, enabling reliable detection of 1-, 2-, 3-, or 4-shorted LED faults within a series segment - critical for maintaining string integrity in headlight modules.

What is the purpose of the EN/UVLO pin on the LT3965EFE-1#TRPBF?

The EN/UVLO pin on the LT3965EFE-1#TRPBF serves dual functions: enabling/disabling the device and providing accurate undervoltage lockout. With a 1.24V falling threshold and externally programmable hysteresis, it ensures the LT3965EFE-1#TRPBF only operates when VIN exceeds SRC by ≥7.1V - preventing unsafe bypass conditions in automotive LED strings.

Does the LT3965EFE-1#TRPBF support I²C multidrop configurations?

Yes - the LT3965EFE-1#TRPBF supports true I²C multidrop with up to 16 devices on one bus via four hardware address pins (ADDR[4:1]). Each device responds to two 7-bit addresses (ACMODE and SCM mode), and the ALERT pin supports I²C Alert Response Address (ARA) to identify fault sources without polling.