38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA Quiescent Current

The LT3971 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 38V. 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 0.33Ω 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 LT3971, 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 LT3971 is available in small 10-lead MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance. A 16-lead MSOP is also offered which has enhanced pin-to-pin fault tolerance.

Vout

Iout

Vref Accuracy

LT3971

Adj

1.2A

2.5%

LT3971-3.3

3.3V

1.2A

2.5%

LT3971-5

5V

1.2A

2.5%

LT3971A

Adj

1.3A

1.5%

LT3971A-5

5V

1.3A

1.5%

Applications

* Automotive Battery Regulation

* Power for Portable Products

* Industrial Supplies

* Ultralow Quiescent Current: 2.8μA IQ Regulating 12VIN to 3.3VOUT* Fixed Output Voltages: 3.3V, 5V, 2.1μA IQ Regulating 12VIN to 3.3VOUT* Low Ripple Burst Mode® Operation: Output Ripple < 15mVP-P* Wide Input Voltage Range: 4.3V to 38V* 1.2A Maximum Output Current* Adjustable Switching Frequency: 200kHz to 2MHz