Overview
Features and Benefits
- Ultralow Quiescent Current: 2.8μA IQ Regulating 12VIN to 3.3VOUT
- Fixed Output Voltages: 3.3V, 5V 2.1μA IQ Regulating 12VIN
- Low Ripple Burst Mode® Operation: Output Ripple < 15mVP-P
- Wide Input Voltage Range: 4.3V to 55V
- 1.2A Maximum Output Current
- Adjustable Switching Frequency: 200kHz to 2MHz
- Synchronizable Between 250kHz to 2MHz
- Fast Transient Response
- Accurate 1V Enable Pin Threshold
- Low Shutdown Current: IQ = 700nA
- Power Good Flag
- Soft-Start CapabilityV
- Internal Compensation
- Saturating Switch Design: 0.44Ω On-Resistance
- Output Voltage: 1.19V to 30V
- Small Thermally Enhanced 10-Pin MSOP Package and (3mm × 3mm) DFN Packages
Product Details
The LT3991 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 55V. Low quiescent current design consumes only 2.8μA 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. An internally compensated current mode topology is used for fast transient response and good loop stability. A high efficiency 0.44Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry. An accurate 1V threshold enable pin can be used to shut down the LT3991, reducing the input supply current to 700nA. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91% of the programmed output voltage. The LT3991 is available in small 10-pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance.
Applications
- Automotive Battery Regulation
- Power for Portable Products
- Industrial Supplies
Product Categories
Markets and Technologies
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)
Documentation & Resources
-
R530 Reliability Data3/26/2018
-
DC1526A - Demo Manual3/12/2010
Tools & Simulations
LTspice
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:
LT3991
Product Recommendations
LT3991 Companion Parts
Design Resources
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Evaluation Boards
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.