Features and Benefits
- Ultralow Quiescent Current:
- 2.7μA IQ at 12VIN to 3.3VOUT
- Low Ripple Burst Mode® Operation
- Output Ripple < 15mVP-P
- Wide Input Range: Operation from 4.3V to 42V
- 2.5A Maximum Output Current
- Excellent Start-Up and Dropout Performance
- Adjustable Switching Frequency: 200kHz to 2MHz
- Synchronizable Between 250kHz to 2MHz
- Accurate Programmable Undervoltage Lockout
- Low Shutdown Current: IQ = 700nA
- Power Good Flag
- Soft-Start Capability
- Thermal Shutdown Protection
- Current Limit Foldback with Soft-Start Override
- Saturating Switch Design: 75mΩ On Resistance
- Small, Thermally Enhanced 16-Lead MSOP Package
The LT3975 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 42V. Low quiescent current design consumes only 2.7μA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application. The LT3975 can supply up to 2.5A of load current and has current limit foldback to limit power dissipation during short circuit. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank.
An internally compensated current mode topology is used for fast transient response and good loop stability. A high efficiency 75mΩ switch is included on the die along with a boost Schottky diode and the necessary oscillator, control, and logic circuitry. An accurate 1.02V threshold enable pin can be driven directly from a microcontroller or used as a programmable undervoltage lockout. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91.6% of the programmed output voltage. The LT3975 is available in a small 16-lead MSOP package with exposed pad for low thermal resistance.
- Automotive Battery Regulation
- Portable Products
- Industrial Supplies
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 1736A is a monolithic step-down DC/DC switching regulator featuring the LT3975. The demo circuit is designed for 3.3V, 2.5A output from a 4.3V to 42V input.
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.