Features and Benefits
- Ultralow Quiescent Current
2.5μA IQ at 12VIN to 3.3VOUT
- Low Ripple Burst Mode® Operation
Output Ripple < 10mVP-P
- Wide Input Voltage Range: 4.2V to 42V Operating
- Adjustable Switching Frequency: 200kHz to 2.2MHz
- Integrated Boost and Catch Diodes
- 750mA Output Current
- Excellent Start-Up and Dropout Performance
- Fixed Output Voltages: 3.3V, 5V
- 1.9μA IQ at 12VIN
- Accurate Programmable Undervoltage Lockout
- Low Shutdown Current: IQ = 0.75μA
- Internal Catch Diode Current Limit
- Power Good Flag
- Thermal Shutdown
- Small, Thermally Enhanced 10-Lead MSOP and (3mm × 3mm) DFN Packages
The LT3973 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 42V, and consumes only 2.5μA of quiescent current. A high efficiency switch is included on the die along with the catch diode, boost diode, and the necessary oscillator, control and logic circuitry. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 10mV in a typical application. A minimum dropout voltage of 530mV is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank. Current mode topology is used for fast transient response and good loop stability. A catch diode current limit provides protection against shorted outputs and overvoltage conditions, with thermal shutdown providing additional fault protection. An accurate programmable undervoltage lockout feature is available, producing a low shutdown current of 0.75μA. A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT3973 is available in small, thermally enhanced 10-lead MSOP and 3mm × 3mm DFN packages.
- Automotive Battery Regulation
- Power for Portable Products
- Industrial Supplies
- Gate Drive Bias
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 1730A features the LT3973, a monolithic step-down switching regulator which consumes only 2.5μA quiescent current. The demo circuit is designed for a 5V, 750mA output from a 5.6V to 42V input. The wide input range of the LT3973 allows a variety of input sources including automotive batteries and 24V industrial supplies. In order to reduce the number of components and solution size, the catch diode and boost diode are integrated. The switching frequency is adjustable up to 2.2MHz. At light loads, the regulator operates in Burst Mode® to maintain high efficiency and low output ripple.
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
Design tools for the following parts are available in LTpowerCAD:
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.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.