Features and Benefits
- Fixed Frequency 1.2MHz/2.2MHz Operation
- Very Low Noise: 1mVP-P Output Ripple
- –5V at 350mA from 5V Input
- –12V at 150mA from 5V Input
- Uses Small Surface Mount Components
- Wide Input Range: 2.6V to 16V
- Low Shutdown Current: <1µA
- Low VCESAT Switch: 400mV at 1A
- Pin-for-Pin Compatible with the LT1611
- Low Profile (1mm) ThinSOT™ Package
Product DetailsThe LT1931/LT1931A are the industry’s highest power inverting SOT-23 current mode DC/DC converters. Both parts include a 1A integrated switch allowing high current outputs to be generated in a small footprint. The LT1931 switches at 1.2MHz while the LT1931A switches at 2.2MHz. These high speeds enable the use of tiny, low cost capacitors and inductors 2mm or less in height. The LT1931 is capable of generating –5V at 350mA or –12V at 150mA from a 5V supply, while the LT1931A can generate –5V at 300mA using significantly smaller inductors. Both parts are easy pin-for-pin upgrades for higher power LT1611 applications.
The LT1931/LT1931A operate in a dual inductor inverting topology that filters both the input side and output side current. Very low output voltage ripple approaching 1mVP-P can be achieved when ceramic output capacitors are used. Fixed frequency switching ensures a clean output free from low frequency noise typically present with charge pump solutions. The low impedance output remains within 1% of nominal during large load steps. The 36V switch allows VIN to VOUT differential of up to 34V.
The LT1931/LT1931A are available in the 5-lead ThinSOT package.
- Disk Drive MR Head Bias
- Digital Camera CCD Bias
- LCD Bias
- GaAs FET Bias
- Local Low Noise/Low Impedance Negative Supply
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 (2)
Demonstration Circuit 383B is multipurpose demonstration board featuring the LT1930 and LT1931. The demo board offers three separate DC/DC converters. The Boost circuit is designed to convert a 5V input to 12V output at 300mA maximum load. The SEPIC circuit generates a 12V/300mA output from a 10V~16V variable input. The Inverter circuit is designed for applications requiring -12V/350mA from a positive 12V input.
Demonstration circuit 397 is a multipurpose DC/DC switching regulator using the LT1930A and LT1931A voltage regulators in a SOT-23 package. The demo board offers three separate DC/DC converters for different applications needs. The boost circuit is designed to convert a 5V input to 12V output at 250mA maximum load. The SEPIC circuit generates a constant 12V/250mA (max load) output with a 10V~16V variable input. The inverter circuit is de-signed for applications requiring negative 12V/250mA (max load) from a positive 12V input. All three circuits are designed to demonstrate fast switching frequency (2.2MHz), an internal 36V/1A switch, wide input range, and small circuit size.
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:
LT1931 Companion Parts
Recommended Related Parts
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.