Features and Benefits
- Wide Input Voltage Range: 3.6V to 34V Operating, 36V Maximum
- 2A Maximum Output Current
- Low Ripple Burst Mode® Operation
50µA IQ at 12VIN to 3.3VOUT
Output Ripple < 15mVP-P
- Adjustable Switching Frequency: 300kHz to 2.8MHz
- Low Shutdown Current: IQ < 1µA
- Integrated Boost Diode
- Integrated Power Schottky Diode
- Power Good Flag
- Saturating Switch Design: 0.18Ω On-Resistance
- 1.265V Feedback Reference Voltage
- Output Voltage: 1.265V to 20V
- Soft-Start Capability
- Small 14-Pin Thermally Enhanced (4mm x 3mm) DFN Package
The LT3681 is an adjustable frequency (300kHz to 2.8MHz) monolithic buck switching regulator that accepts input voltages up to 34V (36V maximum). A high efficiency 0.18Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control, and logic circuitry. An undedicated power Schottky diode is integrated into the LT3681 to minimize the solution size. Current mode topology is used for fast transient response and good loop stability. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mV in a typical application. In addition, the LT3681 can further enhance low output current efficiency by drawing bias current from the output when VOUT is above 3V. Shutdown reduces input supply current to less than 1µA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT3681 is available in 14-Pin 4mm x 3mm DFN package with exposed pads for low thermal resistance.
- Automotive Battery Regulation
- Power for Portable Products
- Distributed Supply Regulation
- Industrial Supplies
- Wall Transformer Regulation
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 1122 features the LT3681 in a 500kHz step-down converter circuit, designed for 3.3V/2A output from a 4.5V to 34V input. The LT3681’s integrated boost diode and catch diode reduce the parts count.
Tools & Simulations
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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.