Analog Devices Inc. LT1374IR-5#PBF

Overview

LT1374IR-5#PBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 4.5A monolithic buck switching regulator in a 16-pin TSSOP package with exposed pad. It operates at a constant 500kHz switching frequency, features cycle-by-cycle current limiting, 0.07Ω switch on-resistance, and 20µA shutdown current. It delivers regulated 5V output for battery-powered systems requiring high efficiency and compact power conversion.

For engineers reviewing the LT1374IR-5#PBF datasheet, LT1374IR-5#PBF pinout, LT1374IR-5#PBF application, or LT1374IR-5#PBF equivalent, key selection criteria include fixed 5V output configuration, 4.5A peak switch current rating, thermal performance in the exposed-pad TSSOP package, and compatibility with standard surface-mount external components including 5µH inductors and solid tantalum output capacitors.

Technical Context

The LT1374IR-5#PBF implements current-mode control with an internal 2.42V reference and dedicated SENSE pin (replacing FB) for fixed 5V regulation. Its bipolar NPN power switch is driven via BOOST pin to achieve saturation, enabling low conduction loss (0.07Ω typical) and >89% efficiency at full load.

It integrates oscillator, error amplifier, slope compensation, and dual shutdown comparators (2.38V UVLO and 0.4V deep shutdown). The 16-pin TSSOP package provides dual VIN and VSW pins shorted externally, GND-connected exposed pad for thermal management, and supports synchronization up to 1MHz when configured with SYNC function.

Key Specifications

Pinout & Package

LT1374IR-5#PBF is housed in a 16-pin plastic TSSOP package (FE16) with exposed thermal pad soldered to PCB ground plane. Dual VIN and VSW pins must be shorted externally; GND pins are internally connected to the exposed pad.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1374IR-5#PBF, LTC3632EMSE-5#PBF offers superior light-load efficiency and extended input range but lacks the BOOST-saturated switch architecture that enables 0.07Ω conduction loss. TPS54560QDGQRQ1 supports higher input voltages and current but requires external compensation and does not provide fixed 5V output without additional components.

Availability

LT1374IR-5#PBF is available at Aetrix Electronics and suitable for portable computers, battery-powered systems, and distributed power applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LT1374IR-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 full product support, documentation, and manufacturing continuity for all LT-branded power ICs.

The LT1374 family was designed as high-current, high-frequency monolithic buck regulators targeting space-constrained, thermally demanding applications where efficiency and reliability outweigh cost sensitivity.

FAQ

What is the maximum continuous output current of the LT1374IR-5#PBF?

The LT1374IR-5#PBF delivers up to 4.25A continuous output at 5V when using a 5µH inductor and 10V input, per the Typical Application Circuit (1374 TA01). Peak switch current is rated at 4.5A up to 50% duty cycle, derating nonlinearly above that - actual output current depends on input voltage, inductor value, and thermal design. With proper PCB copper area under the exposed pad, full 4.25A is sustainable at 85°C ambient.

Does the LT1374IR-5#PBF require an external catch diode?

Yes, the LT1374IR-5#PBF requires an external Schottky catch diode (e.g., MBRS330T3) connected between VSW and GND. Unlike synchronous buck converters, it uses an internal NPN switch and relies on this external diode for freewheeling current path during switch-off time. Diode selection must meet ≥2× output current RMS rating and low forward voltage to maintain efficiency.

How does the BOOST pin function in the LT1374IR-5#PBF?

The BOOST pin in the LT1374IR-5#PBF supplies a voltage higher than VIN to the base drive of the internal NPN power switch, enabling saturation and minimizing V_CE(sat). It is connected to a charge pump formed by an external diode and capacitor (typically 10nF ceramic). This architecture achieves 0.07Ω effective switch resistance - significantly lower than conventional bipolar designs - and improves efficiency from ~75% to >89% at full load.

Can the LT1374IR-5#PBF be synchronized to an external clock?

Yes, the LT1374IR-5#PBF can be synchronized to an external clock via the SYNC pin (Pin 12), which accepts logic-level signals (10–90% duty cycle) from 580kHz to 1MHz. This feature allows noise spectral spreading and eliminates beat frequencies in multi-regulator systems. Note: the standard LT1374IR-5#PBF includes SHDN on Pin 13; for SYNC functionality, the -SYNC variant (e.g., LT1374IR-SYNC) must be selected.

What is the purpose of the BIAS pin on the LT1374IR-5#PBF?

The BIAS pin (Pin 15) on the LT1374IR-5#PBF allows the internal bias circuitry to draw operating current from the regulated 5V output instead of VIN, improving efficiency - especially at high input-to-output voltage ratios and light loads. When connected to VOUT (≥3.3V), it reduces total input supply current by ~3mA. Efficiency gain exceeds 10% at VIN = 20V, VOUT = 5V, and IOUT = 25mA, as documented in the Applications Information section.