Analog Devices Inc. LT3663EDCB

Overview

LT3663EDCB from Analog Devices (formerly Linear Technology) is a 1.5MHz fixed-frequency, current-mode step-down switching regulator with programmable output current limit (0.4A–1.2A), integrated boost diode, and internal compensation. It operates from 7.5V to 36V input (with 60V transient tolerance) and delivers up to 1.2A at fixed 5V output in thermally enhanced 8-lead DFN (2mm × 3mm) package. Used in automotive battery regulation and industrial 24V supply conversion.

For engineers reviewing the LT3663EDCB datasheet, LT3663EDCB pinout, LT3663EDCB application, or LT3663EDCB equivalent, key selection criteria include its programmable current limit (via ILIM resistor), 275mV switch V_CE(SAT) at 1A, thermal shutdown, input overvoltage lockout (39V typ), and compatibility with standard Schottky catch diodes for high-efficiency 5V point-of-load regulation.

Technical Context

The LT3663EDCB implements peak current mode control with fixed 1.5MHz switching frequency, enabling compact external components. Its internal bipolar NPN power switch is driven by a BOOST pin voltage generated via an integrated diode and external capacitor - eliminating need for external bootstrap circuitry.

Output voltage regulation is achieved via feedback to the FB pin (regulated to 0.8V), while output current limiting is independently controlled by the ILIM pin using an external resistor. The device includes undervoltage lockout (7.5V rising), overvoltage lockout (39V rising), and thermal shutdown - all active during 60V transients without latch-up.

Key Specifications

Pinout & Package

LT3663EDCB is housed in an 8-lead plastic DFN package (2mm × 3mm) with exposed GND pad (Pin 9), requiring soldering to PCB ground plane for thermal and electrical performance. Pin pitch is 0.5mm; package conforms to JEDEC MO-229 variation WDDB.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LTC3631EMSE-5#PBF and LT3975EMSE-5#PBF, the LT3663EDCB offers unique integration of programmable current limiting, internal BOOST diode, and fixed 5V output in a thermally optimized DFN - making it optimal for cost-sensitive, medium-current industrial and automotive 5V rails where design simplicity and transient robustness are critical.

Availability

LT3663EDCB is available at Aetrix Electronics and suitable for automotive battery regulation, industrial 24V supply conversion, and wall transformer regulation requiring stable component supply and long-term lifecycle support.

Supply support for LT3663EDCB 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 acquired Linear Technology in 2017 and maintains full product support, datasheets, and application engineering for legacy Linear parts including the LT3663 series.

The LT3663 product line was designed for high-reliability, wide-input-voltage DC/DC conversion in harsh environments - targeting automotive, industrial, and telecom infrastructure where input transients and thermal constraints demand robust, integrated solutions.

FAQ

What is the maximum input voltage rating for the LT3663EDCB?

The LT3663EDCB has an absolute maximum input voltage rating of 60V for nonrepetitive 1-second transients. Continuous operation is specified from 7.5V to 36V. Its input overvoltage lockout activates at 39V (typical), protecting downstream circuitry during automotive load-dump events without requiring external clamping components. This makes the LT3663EDCB particularly suitable for 12V/24V vehicle systems where transient immunity is critical.

Does the LT3663EDCB require external compensation components?

No, the LT3663EDCB is internally compensated - no external compensation network is required. This simplifies design and reduces bill-of-materials count. The internal compensation is optimized for stable operation with standard output capacitor values (≥22µF ceramic) and inductors (e.g., 6.8µH). External compensation is unnecessary unless custom loop response tuning is needed, which is not supported by the LT3663EDCB's fixed architecture.

How is the output current limit set on the LT3663EDCB?

The output current limit on the LT3663EDCB is set by connecting a resistor from the ILIM pin to GND. For the LT3663EDCB-5 variant, a 28.7kΩ resistor programs a 1.2A limit, while 36.5kΩ yields 1.0A. The relationship is linear across 0.4A–1.2A per the datasheet's R_ILIM table. This resistor directly controls average inductor current, enabling precise system-level power dissipation management without sensing resistors in the output path.

Can the LT3663EDCB operate with a 5V input supply?

No, the LT3663EDCB cannot operate with a 5V input. Its minimum operating input voltage is 7.5V (rising UVLO threshold), and startup requires sufficient headroom above the 5V output to bias the internal regulator and BOOST circuit. Attempting to run below 7.5V will result in no switching action. For 5V-input applications, consider alternatives like the LTC3631 or LT3643, which support lower VIN ranges.

What package type and thermal characteristics does the LT3663EDCB use?

The LT3663EDCB uses an 8-lead plastic DFN package (2mm × 3mm) with exposed GND pad (Pin 9), designated DCB. Its junction-to-ambient thermal resistance (θ_JA) is 64°C/W when mounted on a standard 4-layer PCB with thermal vias under the exposed pad. Full 1.2A output current is achievable up to 85°C ambient; derating is required above that. The exposed pad must be soldered to a solid ground plane for both thermal and electrical performance.