Analog Devices Inc. LT1767EMS8-3.3#TRPBF

Overview

LT1767EMS8-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 1.25MHz, 1.5A step-down switching regulator in an 8-pin MSOP package with exposed pad (MS8E), delivering a fixed 3.3V output with ±2% tolerance, 0.22Ω internal switch, and 1.2V feedback reference. It operates from 3V to 25V input and supports synchronization up to 2MHz for noise-sensitive applications such as portable computers and DSL modems.

For engineers reviewing the LT1767EMS8-3.3#TRPBF datasheet, LT1767EMS8-3.3#TRPBF pinout, LT1767EMS8-3.3#TRPBF application, or LT1767EMS8-3.3#TRPBF equivalent, key selection considerations include its constant-frequency current-mode control architecture, thermal performance in the MS8E package (θ_JA = 40°C/W), shutdown current of 6µA, and fixed 3.3V output configuration requiring no external feedback resistors.

Technical Context

The LT1767EMS8-3.3#TRPBF implements a current-mode, constant-frequency buck topology with cycle-by-cycle peak current limiting and internal 1.25MHz oscillator. Its bipolar NPN power switch is driven via an external BOOST circuit to achieve low saturation voltage (~330mV at –1.5A), enabling high efficiency across wide input ranges.

Feedback is internally configured for 3.3V output: the FB pin is directly connected to V_OUT, eliminating external resistor dividers. The VC pin serves as error amplifier output and current limit threshold control point, ranging from 0.35V (light load) to 0.9V (full load), supporting loop compensation and current clamping.

Key Specifications

Pinout & Package

The LT1767EMS8-3.3#TRPBF is housed in an 8-lead plastic MSOP package with exposed thermal pad (MS8E), where the exposed pad is electrically and thermally connected to GND. Mounting requires soldering the pad to a large PCB copper area for optimal thermal performance (θ_JA = 40°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1767EMS8-3.3#TRPBF, the LTC3605EMS8E-3.3#PBF offers higher frequency and integration but reduced thermal headroom, while the TPS54331DR provides greater current and adjustability at the cost of added external components and less optimized low-duty-cycle efficiency.

Availability

LT1767EMS8-3.3#TRPBF is available at Aetrix Electronics and suitable for DSL modems, portable computers, and industrial wall adapter interfaces requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LT1767EMS8-3.3#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 acquired Linear Technology in 2017 and maintains its legacy high-performance power management portfolio, emphasizing precision, reliability, and ruggedness for industrial and communications applications.

The LT1767 family was designed as a monolithic, high-frequency buck regulator targeting space-constrained, thermally demanding applications where fixed-output simplicity, current-mode stability, and wide-input operation are essential - especially in portable and telecom infrastructure equipment.

FAQ

What is the maximum continuous output current of the LT1767EMS8-3.3#TRPBF?

The LT1767EMS8-3.3#TRPBF delivers up to 1.5A continuous output current under proper thermal conditions - specifically when mounted on a PCB with adequate copper pour on the exposed GND pad (MS8E package) and ambient temperature ≤85°C. Derating applies above 85°C per the θ_JA = 40°C/W specification. At 125°C junction, maximum usable current drops to approximately 1.1A.

Does the LT1767EMS8-3.3#TRPBF require external feedback resistors?

No - the LT1767EMS8-3.3#TRPBF is a fixed-output variant with internal resistor divider connecting the FB pin directly to V_OUT. This eliminates external feedback components and associated placement/tolerance errors. The internal 1.2V reference and precision divider ensure ±2% output accuracy over temperature and line/load conditions.

Can the LT1767EMS8-3.3#TRPBF synchronize to an external clock?

Yes - the LT1767EMS8-3.3#TRPBF supports external synchronization via the SYNC pin, accepting logic-level signals from 1.5MHz to 2MHz with 20–80% duty cycle. This feature enables EMI reduction through frequency alignment and avoids beat frequencies in multi-regulator systems. When unused, SYNC must be grounded.

What thermal design is required for the LT1767EMS8-3.3#TRPBF in full-load operation?

The LT1767EMS8-3.3#TRPBF in MS8E package requires soldering the exposed thermal pad to a minimum 100mm² copper area on the PCB layer, connected via ≥4 thermal vias (0.3mm diameter) to inner or back-side ground planes. Without this, θ_JA degrades from 40°C/W to >110°C/W, risking thermal shutdown at 1.5A. Thermal simulation or IR imaging is recommended for final layout validation.

What is the purpose of the BOOST pin on the LT1767EMS8-3.3#TRPBF?

The BOOST pin on the LT1767EMS8-3.3#TRPBF supplies elevated gate drive to the internal NPN switch, enabling saturation and minimizing V_CE(SAT) to ~330mV. It is charged via an external 0.1µF capacitor and Schottky diode (e.g., CMDSH-3) tied to V_OUT - ensuring efficient operation even at low input-to-output voltage ratios, unlike standard buck controllers relying solely on VIN-referenced drive.