Analog Devices Inc. LT3973EMSE-5#TRPBF

Overview

LT3973EMSE-5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed 5V, 750mA monolithic step-down DC/DC regulator with integrated power switch, catch diode, and boost diode. It operates from 4.2V to 42V input, delivers ultralow 2.5µA quiescent current at 12V_IN, maintains <10mV_P-P output ripple in Burst Mode, and supports automotive cold-crank dropout with 530mV minimum dropout voltage.

For engineers reviewing the LT3973EMSE-5#TRPBF datasheet, LT3973EMSE-5#TRPBF pinout, LT3973EMSE-5#TRPBF application, or LT3973EMSE-5#TRPBF equivalent, key selection criteria include its fixed 5V output, 10-lead MSOP package with exposed thermal pad, programmable UVLO, open-drain power-good flag, and compatibility with high-input-voltage industrial and automotive power rails.

Technical Context

The LT3973EMSE-5#TRPBF uses constant-frequency current-mode control with adjustable switching frequency (200kHz–2.2MHz via RT resistor) and internal slope compensation. Its bipolar NPN switch driver relies on an external BOOST capacitor to achieve full saturation, enabling robust dropout performance down to 530mV.

Burst Mode operation reduces quiescent current to 1.8µA at light loads while maintaining output regulation and sub-10mV_P-P ripple. The device integrates undervoltage lockout with 30mV hysteresis, thermal shutdown, catch-diode current limiting (1.15A typical), and a power-good comparator that asserts when V_OUT reaches 90% of 5V.

Key Specifications

Pinout & Package

LT3973EMSE-5#TRPBF is housed in a thermally enhanced 10-lead plastic MSOP package (3mm × 3mm) with exposed GND pad (Pin 11) requiring PCB soldering for thermal and electrical integrity. θ_JA = 45°C/W, θ_JC = 10°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3630EMS-5#PBF and TPS54340DDAR, the LT3973EMSE-5#TRPBF delivers higher guaranteed output current (750mA) with fully integrated diodes and lower quiescent current (2.5µA), making it optimal for space-constrained, ultra-low-power 5V systems where fixed output is acceptable.

Availability

LT3973EMSE-5#TRPBF is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, and portable medical devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT3973EMSE-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 its legacy of high-performance power management ICs with rigorous automotive and industrial qualification.

The LT3973 product line was designed specifically for high-input-voltage, ultralow-quiescent-current DC/DC conversion in harsh environments-targeting automotive infotainment, ADAS camera modules, and industrial automation where reliability and efficiency are critical.

FAQ

What is the output voltage tolerance of the LT3973EMSE-5#TRPBF over temperature?

The LT3973EMSE-5#TRPBF delivers a fixed 5V output with ±1.2% tolerance across its full operating junction temperature range of –40°C to 125°C, as specified in the Electrical Characteristics table. This tight regulation is achieved via an internal precision resistor divider referenced to a 1.21V bandgap, ensuring stable 5V rail generation without external feedback components.

Does the LT3973EMSE-5#TRPBF require external diodes?

No, the LT3973EMSE-5#TRPBF integrates both the catch diode and boost diode on-die, eliminating the need for external diodes. This integration reduces bill-of-materials count, PCB footprint, and layout complexity while improving reliability-unlike many competing buck regulators that require discrete Schottky diodes for boost and catch functions.

How does the LT3973EMSE-5#TRPBF handle automotive cold-crank conditions?

The LT3973EMSE-5#TRPBF maintains regulation during cold-crank events by enforcing a minimum 530mV dropout voltage: when VIN drops near VOUT, it extends duty cycle up to ~97.5% and skips switch-off cycles to sustain 5V output. This behavior, combined with 4.2V minimum operating voltage, ensures uninterrupted operation even when battery voltage sags to 5.5V.

What is the purpose of the OUT pin on the LT3973EMSE-5#TRPBF?

The OUT pin on the LT3973EMSE-5#TRPBF serves as the dropout regulation reference. When tied to VOUT (as required for 5V operation), it enables the internal comparator to enforce a minimum 530mV difference between VIN and VOUT, ensuring the boost capacitor remains charged and the internal NPN switch stays saturated during low-input conditions.

Can the LT3973EMSE-5#TRPBF be synchronized to an external clock?

No, the LT3973EMSE-5#TRPBF does not support external clock synchronization. Its switching frequency is set solely by the resistor connected between the RT pin and GND, with a programmable range of 200kHz to 2.2MHz. For synchronized operation, designers must select alternative regulators such as the LT8614 or MPQ4420A that include SYNC pins.