Analog Devices Inc. LT3922IUFD-1#PBF

Overview

LT3922IUFD-1#PBF from Analog Devices is a monolithic synchronous step-up LED driver IC with ±2.5% LED current regulation, 2.3A internal switches, and 25,000:1 PWM dimming capability at 100Hz. It operates from 2.8V to 36V input, supports up to 34V LED string voltage, and integrates Silent Switcher® architecture for low EMI in automotive lighting systems.

For engineers reviewing the LT3922IUFD-1#PBF datasheet, LT3922IUFD-1#PBF pinout, LT3922IUFD-1#PBF application, or LT3922IUFD-1#PBF equivalent, key selection considerations include its 28-lead QFN package, AEC-Q100 qualification, dual analog/digital LED current control, open/short LED fault detection, and programmable 200kHz–2MHz switching frequency with spread spectrum support.

Technical Context

The LT3922IUFD-1#PBF implements fixed-frequency peak-current-mode control with independent current and voltage regulation loops. Its dual-switch architecture enables boost, buck, and buck-boost topologies, while the integrated 2V reference (±0.5% over temperature), 1.2V FB threshold, and 140µA/V current error amplifier transconductance ensure precise LED current stability across input and output variations.

It features dedicated hardware for high-fidelity PWM dimming: an internal PWM generator (7.34–129Hz) controlled by RP, a high-speed PWMTG gate driver (110ns turn-on), and analog/digital CTRL interface supporting both 250mV–1.25V DC and 12.5%–62.5% duty-cycle pulse inputs - all coordinated within a single monolithic die with thermally enhanced 4mm × 5mm QFN packaging.

Key Specifications

Pinout & Package

LT3922IUFD-1#PBF is housed in a thermally enhanced 28-lead plastic QFN (4mm × 5mm) with exposed GND pad (Pin 29). The package supports high-power dissipation in compact automotive and industrial LED modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3922EUFD-1#PBF, the LT3922IUFD-1#PBF adds AEC-Q100 qualification and automotive reliability documentation, while LT3922HUFD-1#PBF extends thermal operation to 150°C - enabling deployment across full automotive temperature zones without derating.

Availability

LT3922IUFD-1#PBF is available at Aetrix Electronics and suitable for automotive headlamps, machine vision lighting, commercial signage, and avionics panel lighting requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.

Supply support for LT3922IUFD-1#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, serving industrial, automotive, communications, and healthcare markets.

The LT3922IUFD-1#PBF belongs to Analog Devices' Silent Switcher LED driver product line, engineered specifically for high-reliability, low-EMI automotive lighting applications demanding precise current regulation and wide dimming range.

FAQ

What is the maximum LED string voltage supported by the LT3922IUFD-1#PBF?

The LT3922IUFD-1#PBF supports up to 34V LED string voltage, verified across its full operating temperature range (−40°C to +125°C). This rating is derived from the absolute maximum VOUT specification and confirmed by typical performance data showing stable regulation at 33V output with 11 LEDs. The device maintains ±2.5% current regulation even at this maximum string voltage when used with appropriate external components.

Does the LT3922IUFD-1#PBF require external MOSFETs for PWM dimming?

No, the LT3922IUFD-1#PBF integrates a dedicated PWMTG output pin that directly drives the gate of an external high-side PMOS transistor for PWM dimming. While it does not include the PMOS itself, the driver circuitry - including 110ns turn-on propagation delay and 10V gate drive swing (VOUT – VPWMTG) - is fully integrated, eliminating the need for additional gate driver ICs in the LT3922IUFD-1#PBF design.

How does the LT3922IUFD-1#PBF achieve 25,000:1 PWM dimming?

The LT3922IUFD-1#PBF achieves 25,000:1 PWM dimming by accepting external 100Hz PWM signals at the PWM pin, which directly controls the PWMTG output with minimal propagation delay (110ns turn-on). This external synchronization bypasses the internal PWM generator and leverages the fast-switching capability of the integrated driver and external PMOS, enabling ultra-low-duty-cycle dimming down to 0.004% while maintaining LED current accuracy and thermal stability in the LT3922IUFD-1#PBF.

What fault conditions does the LT3922IUFD-1#PBF detect and report?

The LT3922IUFD-1#PBF detects and reports two primary fault conditions via its open-drain FAULT pin: open-circuit LED strings (when VFB > 1.14V and VISP−VISN < 10mV) and shorted LED strings (when VISP−VISN > 150mV for >300µs or >700mV instantaneously). These thresholds are specified over temperature and validated in production test for the LT3922IUFD-1#PBF, ensuring reliable fault coverage in automotive and industrial deployments.

Is the LT3922IUFD-1#PBF pin-compatible with other variants in the LT3922-1 family?

Yes, the LT3922IUFD-1#PBF is pin-compatible with all UFD-package variants of the LT3922-1 family, including LT3922EUFD-1#PBF and LT3922HUFD-1#PBF. All share identical 28-lead QFN (4mm × 5mm) footprint, pin assignment, and electrical interface. Differences are limited to temperature grade, AEC-Q100 qualification status, and reliability test coverage - making the LT3922IUFD-1#PBF a drop-in replacement for design upgrades requiring automotive qualification.