LT1939

PRODUCTION

Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller

Part Models: 4
1ku List Price: Starting From $3.66

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Overview

Wide Input Range: 3V to 25V
Short-Circuit Protected Over Full Input Range
2A Output Current Capability
Adjustable/Synchronizable Fixed Frequency Operation from 250kHz to 2.2MHz
Soft-Start/Tracking Capability
Output Adjustable Down to 0.8V
Adjustable Linear Regulator/Driver with 13mA Output Capability
Power Good Comparator with Complementary Outputs
Low Shutdown Current: 12μA
Thermally Enhanced 3mm × 3mm DFN Package

The LT1939 is a current mode PWM step-down DC/DC converter with an internal 2.3A switch. The wide input range of 3V to 25V makes the LT1939 suitable for regulating power from a wide variety of sources, including automotive batteries, industrial supplies and unregulated wall adapters.

Resistor-programmable 250kHz to 2.2MHz frequency range and synchronization capability enable optimization between efficiency and external component size. Cycle-by-cycle current limit, frequency foldback and thermal shutdown provide protection against a shorted output. The soft-start feature controls the ramp rate of the output voltage, eliminating input current surge during start-up, and also provides output tracking.

The LT1939 contains an internal NPN transistor with feedback control which can be conﬁgured as a linear regulator or as a linear regulator controller.

The LT1939’s low current shutdown mode (<12μA) enables easy power management in battery-powered systems.

Applications

Automotive Battery Regulation
Industrial Control
Wall Transformer Regulation
Distributed Power Regulation

Part Models: 4
1ku List Price: Starting From $3.66

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT1939EDD#PBF	12-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1939EDD#TRPBF	12-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1939IDD#PBF	12-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1939IDD#TRPBF	12-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Circuit Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Oscillators 1
LTC6908		Resistor Set SOT-23 Oscillator with Spread Spectrum Modulation
Power System Management (PSM) & Sequencers 1
LTC2974	RECOMMENDED FOR NEW DESIGNS	4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
Protection Switches & Controllers 1
LT4363	RECOMMENDED FOR NEW DESIGNS	High Voltage Surge Stopper with Current Limit

Tools & Simulations

LTspice 1

LT1939 Demo Circuit - Monolithic 2A Step-Down Regulator Plus LDO (12V to 5V @ 1A & 3.3V @ 1A)

Models for the following parts are available in LTspice:

LT1939

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.