LT3971A/LT3971A-5 Applications, LT3971A/LT3971A-5 Features

　　The LT3971A/LT3971A-5 is a 38V, 1.3A, 2MHz step-down switching regulator with 2.2μA quiescent current.

　　1. Specific description

　　The LT971A is an adjustable frequency, monolithic, step-down switching regulator that accepts a wide input voltage range up to 38V. The low quiescent current design consumes only 2.8μA of supply current when in no-load regulation. Low ripple Burst Mode operation maintains high efficiency at low output currents and keeps output ripple below 15mV in typical applications. An internally compensated current mode topology is used to achieve fast transient response and good loop stability. A high efficiency 0.33Ω switch and a boost Schottky diode are built into the chip along with the necessary oscillator, controller and logic circuits . An enable pin with an accurate 1V threshold can be used to shut down the LT3971A, reducing the input supply current to 700nA. A capacitor on the SS pin provides controlled inrush current (soft start). The power good flag circuit will indicate when VOUT reaches 91% of the programmed output voltage. The LT3971A is available in a small outline 10-lead MSOP package with exposed pad for low thermal resistance protection.

　　The LT3971A and LT3971A-5 have a more accurate reference voltage than the LT3971 and LT3971-5. The LT3971A-5 also has a specified VOUT pin current and ABSMAX (absolute maximum) current. These features are important for USB applications.

　　2. Product Features

　　Ultra-low quiescent current: 2.8μA IQ regulates 12VIN to 3.3VOUT

　　Fixed output voltage: 5V 2.2μA IQ Regulate 12VIN to 5VOUT

　　Low ripple Burst Mode (BurstMode?) operation: output ripple <15mVP-P

　　Wide input voltage range: 4.3V to 38V

　　1.3A maximum output current

　　Adjustable switching frequency: 200kHz to 2MHz

　　Synchronizable frequency range: 250kHz to 2MHz

　　Fast transient response

　　Accurate 1V enable pin threshold

　　Low shutdown current: IQ=700nA

　　Power good flag

　　Soft start capability

　　Internal compensation

　　Output voltage: 1.19V to 30V

　　Small thermally enhanced 10-pin MSOP package

　　3. Application

　　USB VBUS regulation

　　Car battery conditioning

　　Power supply for portable products

　　Industrial power supply

　　4. Typical Applications

　　No-load supply current

　　5. Pin Diagram