Analog Devices Inc. LT1375CS8-5#TRPBF

Overview

LT1375CS8-5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 1.5A, 500kHz monolithic synchronous buck switching regulator in an 8-pin SOIC package. It integrates a bipolar NPN power switch with current-mode control, 0.4Ω typical on-resistance, 2.5mA quiescent supply current, and cycle-by-cycle current limiting. It delivers regulated 5V output from 6V–25V input for battery-powered portable computers and distributed power systems.

For engineers reviewing the LT1375CS8-5#TRPBF datasheet, LT1375CS8-5#TRPBF pinout, LT1375CS8-5#TRPBF application, or LT1375CS8-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 500kHz constant-frequency operation, BOOST pin requirement for switch saturation, thermal shutdown protection, and compatibility with standard surface-mount 5µH inductors and tantalum output capacitors.

Technical Context

The LT1375CS8-5#TRPBF implements current-mode control with a 500kHz oscillator and internal slope compensation to prevent subharmonic oscillation. Its bipolar NPN switch is driven via an external BOOST capacitor to achieve low 0.4Ω on-resistance and >87% efficiency at full load.

It features dual shutdown thresholds: 2.38V for undervoltage lockout (UVLO) and 0.4V for micropower shutdown (20µA), plus FB/SENSE pin monitoring of the 5V output with foldback current limiting below 1.7V and frequency reduction below 1V during fault conditions.

Key Specifications

Pinout & Package

LT1375CS8-5#TRPBF is housed in an 8-lead plastic SOIC (S8) package with exposed pad thermal enhancement. Pin 1 is marked by a beveled corner; device orientation follows JEDEC MS-012 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1375CS8-5#TRPBF, LTC3605EDE-5#TRPBF offers higher integration and smaller solution size but lower current rating and no BOOST-based efficiency optimization at high VIN; TPS54202DDCR provides greater flexibility and current headroom but demands more design effort for loop stability and layout.

Availability

LT1375CS8-5#TRPBF is available at Aetrix Electronics and suitable for portable computers, battery-powered instrumentation, and distributed power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT1375CS8-5#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 full technical and manufacturing continuity for the LT® product family, renowned for high-performance analog and power management ICs.

The LT1375 belongs to Linear's monolithic buck regulator product line, designed specifically for compact, high-efficiency DC-DC conversion in portable and battery-sensitive applications where thermal performance and low quiescent current are critical.

FAQ

What is the minimum input voltage required for LT1375CS8-5#TRPBF to regulate 5V output?

The LT1375CS8-5#TRPBF requires a minimum input voltage of 6V to maintain regulation at full load, as specified in the Absolute Maximum Ratings table and confirmed in Typical Performance Characteristics (Figure G12). Below 6V, the internal bias circuitry cannot sustain stable reference voltage and oscillator frequency - resulting in loss of regulation. This limit is independent of external components and applies across the full operating temperature range.

Does LT1375CS8-5#TRPBF require an external BOOST capacitor, and why?

Yes, LT1375CS8-5#TRPBF requires an external BOOST capacitor (and associated diode) connected between VIN and BOOST pins. This network generates a voltage ~5V above VIN to fully saturate the internal bipolar NPN power switch - reducing on-resistance to 0.4Ω and enabling >87% efficiency. Without it, switch conduction losses increase dramatically, degrading thermal performance and output capability.

Can LT1375CS8-5#TRPBF be synchronized to an external clock?

No, LT1375CS8-5#TRPBF does not support external synchronization. The SYNC pin is only present on the LT1375 variant (e.g., LT1375CS8#TRPBF), not on the -5 fixed-output version. The LT1375CS8-5#TRPBF operates exclusively at its internal 500kHz oscillator frequency and lacks both SYNC pin functionality and related timing circuitry.

What is the role of the FB/SENSE pin on LT1375CS8-5#TRPBF?

On LT1375CS8-5#TRPBF, the FB/SENSE pin serves as a direct 5V output monitor - connected to the regulated output rail - rather than a feedback divider node. It enables undervoltage lockout (2.38V threshold), foldback current limiting (<1.7V), and frequency reduction (<1V) during fault conditions. No external resistors are needed, distinguishing it from adjustable versions like LT1375CS8.

Is thermal derating required for LT1375CS8-5#TRPBF at elevated ambient temperatures?

Yes, thermal derating is required. With θJA = 120°C/W (typical for SOIC-8 on standard FR-4), the LT1375CS8-5#TRPBF junction temperature rises ~120°C per watt of dissipated power. At 1.25A output into 5V with 12V input, power dissipation exceeds 1W - requiring either reduced load current above 60°C ambient or use of PCB copper pours/fused corner pads to lower effective θJA per the manufacturer's layout guidelines.