Features and Benefits
- Low Ripple Burst Mode® Operation
- 2.5μA IQ at 12VIN to 3.3VOUT
- Output Ripple < 5mVP-P
- Wide Input Voltage Range: 4.2V to 62V Operating
- Adjustable Switching Frequency: 200kHz to 2.2MHz
- Integrated Boost and Catch Diodes
- 350mA Output Current
- Fixed Output Voltages:
- 3.3V, 5V
- 2μA IQ at 12VIN
- Accurate Programmable Undervoltage Lockout
- FMEA Fault Tolerant (MSOP Package)
- Output Stays at or Below Regulation Voltage During
- Adjacent Pin Short or When a Pin is Left Floating
- Low Shutdown Current: IQ = 0.7μA
- Internal Sense Limits Catch Diode Current
- Power Good Flag
- Small, Thermally Enhanced 16-Pin MSOP and (3mm × 3mm) DFN Packages
The LT3990 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 62V, 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 5mV in a typical application. 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. An accurate programmable undervoltage lockout feature is available, producing a low shutdown current of 0.7μA. A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT3990 is available in small, thermally enhanced 16-pin MSOP and 3mm × 3mm DFN packages.
- Automotive Battery Regulation
- Power for 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 1471 is a monolithic step-down DC/DC switching regulator featuring the LT3990. The switching frequency is adjustable up to 2.2MHz. The demo circuit is designed for 5V, 350mA output from a 6.5V to 62V input. The wide input range of the LT3990 allows a variety of input sources including automotive batteries and 24V industrial supplies. Low ripple Burst Mode increases the efficiency at the light load while keeping the output ripple below 5mV in a typical application. The part is in shutdown when the EN pin is low and active when the pin is high. The threshold of the EN pin is accurate at 1V when VIN is above 4.2V. Adding a resistor divider from VIN to EN can program the LT3990 to regulate the output only when VIN is above a desired voltage. The catch diode and boost diode are integrated to reduce the components count and solution size. The circuit consumes only 2.5μA of quiescent current.
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:
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Sample & Buy
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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.