42V, 2.5A Synchronous Step-Down Regulator with Current Sense and 2.5μA Quiescent Current

The LT8611 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 2.5μA of quiescent current. Top and bottom power switches are included with all necessary circuitry to minimize the need for external components. The built-in current sense amplifier with monitor and control pins allows accurate input or output current regulation and limiting. Low ripple Burst Mode operation enables high efficiency down to very low output currents while keeping the output ripple below 10mVP-P. A SYNC pin allows synchronization to an external clock. Internal compensation with peak current mode topology allows the use of small inductors and results in fast transient response and good loop stability. The EN/UV pin has an accurate 1V threshold and can be used to program VIN undervoltage lockout or to shut down the LT8611 reducing the input supply current to 1μA. A capacitor on the TR/SS pin programs the output voltage ramp rate during start-up. The PG flag signals when VOUT is within ±9% of the programmed output voltage as well as fault conditions. The LT8611 is available in a small 24-lead 3mm × 5mm QFN package with exposed pad for low thermal resistance.

Applications

* Automotive and Industrial Supplies

* General Purpose Step-Down

* CCCV Power Supplies

* Rail-to-Rail Current Sense Amplifier with Monitor

* Wide Input Voltage Range: 3.4V to 42V

* Ultralow Quiescent Current Burst Mode® Operation:

* 2.5μA IQ Regulating 12VIN to 3.3VOUT

* Output Ripple < 10mVP-P

* High Efficiency Synchronous Operation:

* 96% Efficiency at 1A, 5VOUT from 12VIN

* 94% Efficiency at 1A, 3.3VOUT from 12VIN

* Fast Minimum Switch-On Time: 50ns

* Low Dropout Under All Conditions: 200mV at 1A