Analog Devices Inc. LT1767EMS8-5#PBF

Overview

LT1767EMS8-5#PBF from Analog Devices (formerly Linear Technology) is a monolithic 1.25MHz, 1.5A step-down switching regulator with fixed 5V output, 0.22Ω internal NPN switch, 2% output tolerance, and MSOP-8 package with exposed pad. It delivers high efficiency in battery-powered systems, wall adapters, and DSL modems requiring compact, thermally robust DC/DC conversion.

For engineers reviewing the LT1767EMS8-5#PBF datasheet, LT1767EMS8-5#PBF pinout, LT1767EMS8-5#PBF application, or LT1767EMS8-5#PBF equivalent, key selection criteria include its constant-frequency current-mode control, 3V–25V input range, 6µA shutdown current, synchronization capability up to 2MHz, and thermal performance enabled by the MS8E-compatible exposed-pad MSOP package.

Technical Context

The LT1767EMS8-5#PBF implements a fixed-output, current-mode buck topology with an integrated 1.5A bipolar NPN power switch and on-chip 1.25MHz oscillator. Its BOOST pin enables saturation drive for low conduction loss (330mV typical at –1.5A), while the VC pin serves as both error amplifier output and peak-current comparator input for precise load regulation.

It features cycle-by-cycle current limiting independent of duty cycle, internal 1.2V feedback reference (internally divided for 5V output), and built-in undervoltage lockout (2.6V threshold). The device supports external synchronization (1.5–2MHz), operates across –40°C to 125°C junction temperature, and uses a fused lead-frame MSOP-8 package with GND-connected exposed pad for θ_JA = 40°C/W.

Key Specifications

Pinout & Package

The LT1767EMS8-5#PBF is housed in an 8-lead plastic MSOP package with exposed thermal pad (MS8E), where Pin 5 (GND) and the exposed pad are electrically connected to system ground. This configuration achieves θ_JA = 40°C/W when soldered to ≥1 cm² copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3652EMSE-5#PBF and TPS54331DR, the LT1767EMS8-5#PBF offers superior thermal performance per mm² (40°C/W vs. >70°C/W), eliminates feedback resistor placement errors via fixed 5V, and enables smaller magnetics through 1.25MHz operation-making it optimal for compact, high-reliability 5V conversion where input stays ≤25V.

Availability

LT1767EMS8-5#PBF is available at Aetrix Electronics and suitable for DSL modems, portable computers, and battery-powered systems requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for LT1767EMS8-5#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 acquired Linear Technology in 2017 and maintains its legacy precision power portfolio. Linear pioneered high-performance monolithic switching regulators with integrated power switches and advanced control architectures.

The LT1767EMS8-5#PBF belongs to Linear's high-frequency buck regulator family designed for space-constrained, thermally demanding applications in communications, computing, and portable instrumentation-emphasizing integration, efficiency, and ease of use.

FAQ

What is the maximum continuous output current of the LT1767EMS8-5#PBF?

The LT1767EMS8-5#PBF delivers up to 1.5A continuous output current under proper thermal conditions: ambient temperature ≤85°C, PCB with ≥1 cm² copper pour under the exposed pad, and adequate airflow. At higher ambient or with limited copper, derating applies-e.g., 1.27A at 125°C junction (per datasheet Figure G12). The 1.5A rating is guaranteed across –40°C to 125°C junction temperature with cycle-by-cycle current limiting active.

Does the LT1767EMS8-5#PBF require external feedback resistors to set the 5V output?

No, the LT1767EMS8-5#PBF does not require external feedback resistors. It integrates the precise resistor divider internally to generate the 5V output from the 1.2V internal reference. The FB pin is internally connected to the output, eliminating layout sensitivity, resistor tolerance errors, and thermal drift-ensuring 2% total output tolerance over temperature and line/load conditions.

Can the LT1767EMS8-5#PBF synchronize to an external clock, and what is the valid frequency range?

Yes, the LT1767EMS8-5#PBF supports external synchronization via the SYNC pin. It accepts logic-level signals (20–80% duty cycle) from 1.5MHz to 2MHz. When synchronized, the internal oscillator locks to the external signal-enabling EMI reduction by shifting switching noise out of sensitive bands or aligning with system timing domains. If unused, SYNC must be grounded to prevent noise coupling.

What is the purpose of the BOOST pin on the LT1767EMS8-5#PBF, and what components are required?

The BOOST pin on the LT1767EMS8-5#PBF supplies a voltage higher than VIN to fully saturate the internal NPN switch, reducing conduction loss to 330mV typical. It requires an external 0.1µF capacitor and Schottky diode (e.g., CMDSH-3), with the diode anode typically tied to the 5V output. This generates ~VIN + 5V at BOOST, ensuring >2.7V headroom for switch drive across the full input range.

How does the LT1767EMS8-5#PBF handle thermal management, and what PCB layout practices are critical?

The LT1767EMS8-5#PBF relies on its exposed thermal pad (connected to Pin 5/GND) for heat dissipation. To achieve the rated θ_JA = 40°C/W, the pad must be soldered to ≥1 cm² of inner/outer-layer copper with ≥4 thermal vias (0.3mm diameter) to internal ground planes. VIN and SW traces must be short and wide; input/output capacitors must be placed adjacent to their respective pins; and the GND path between IC and bulk capacitors must be low-inductance.