Analog Devices Inc. LT1576CS8-5#PBF

Overview

LT1576CS8-5#PBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 1.25A monolithic step-down switching regulator in fused-lead SO-8 package, featuring 200kHz current-mode control, 0.2Ω switch on-resistance, and integrated shutdown function. It operates from 6V to 25V input, delivers regulated 5V output with ±1.2% accuracy, and is optimized for portable computers and battery-powered systems requiring high efficiency at light loads.

For engineers reviewing the LT1576CS8-5#PBF datasheet, LT1576CS8-5#PBF pinout, LT1576CS8-5#PBF application, or LT1576CS8-5#PBF equivalent, key selection considerations include its fixed 5V SENSE-pin architecture, fused-ground thermal performance (θ_JA = 80°C/W), cycle-by-cycle current limiting, and compatibility with standard surface-mount inductors down to 15µH.

Technical Context

The LT1576CS8-5#PBF implements constant-frequency current-mode control with internal 1.21V reference and slope compensation to prevent subharmonic oscillation. Its fused-lead SO-8 package isolates high-current switching paths (VSW, VIN, BOOST) from low-noise control pins (SENSE, VC, BIAS), improving EMI performance and thermal dissipation.

It features dual shutdown thresholds: 2.42V UVLO lockout and 0.37V micropower shutdown, plus foldback protection that reduces switching frequency and current limit when SENSE voltage drops below 0.7V-critical for short-circuit survival without external circuitry.

Key Specifications

Pinout & Package

Fused-lead 8-lead plastic SOIC (SO-8) package with exposed ground lead thermally bonded to die attach pad; θ_JA = 80°C/W when fused ground pin is soldered to large copper area.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output buck regulator applications.

Compared with LTC3605EDE-5#PBF and TPS54202DRCT, the LT1576CS8-5#PBF delivers unique value in wide-input, thermally demanding applications through its fused SO-8 package, integrated BOOST-driven bipolar switch, and autonomous foldback protection-features absent in both alternatives.

Availability

LT1576CS8-5#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, and distributed power architectures requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LT1576CS8-5#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LT1576 product line was designed specifically for noise-sensitive, wide-input-range DC/DC conversion in portable and industrial equipment-emphasizing thermal robustness, EMI control, and autonomous fault protection without external components.

FAQ

What is the maximum continuous output current of the LT1576CS8-5#PBF?

The LT1576CS8-5#PBF delivers 1.25A continuously at V_IN = 10V with a 15µH inductor. At higher input voltages (e.g., 25V), maximum load current drops to ~0.6A due to increased inductor ripple current. For loads above 1A, inductor value must be increased to 60µH per datasheet guidance. Derating is required above 125°C junction temperature.

Does the LT1576CS8-5#PBF require an external feedback resistor network?

No. The LT1576CS8-5#PBF uses an internal resistor divider to set the fixed 5V output; Pin 7 functions as SENSE-not FB-and connects directly to the output. This eliminates external resistor tolerance errors and simplifies layout. External resistors are only required for adjustable-output variants like LT1576CS8.

How does the fused ground lead in the SO-8 package improve thermal performance of the LT1576CS8-5#PBF?

The fused ground lead in the LT1576CS8-5#PBF's SO-8 package provides a low-thermal-resistance path from the die to the PCB ground plane, achieving θ_JA = 80°C/W (vs. >120°C/W for standard SO-8). This allows sustained 1.25A operation at 125°C ambient without heatsinking-critical for sealed or convection-limited enclosures.

What protection features are built into the LT1576CS8-5#PBF for short-circuit conditions?

The LT1576CS8-5#PBF includes autonomous foldback protection: when SENSE voltage falls below 0.7V, it reduces switching frequency (~5:1) and peak current limit (from 1.5A to <0.77A) to limit power dissipation in the IC, catch diode, and inductor. This occurs without external components and prevents thermal runaway during sustained shorts.

Can the LT1576CS8-5#PBF be synchronized to an external clock?

No-the LT1576CS8-5#PBF uses SHDN on Pin 8 and does not include SYNC functionality. Synchronization is only available on -SYNC variants (e.g., LT1576CS8-5#PBF-SYNC). For timing-critical systems requiring phase alignment, the -SYNC version must be selected instead of LT1576CS8-5#PBF.