Features

• Rail-to-Rail Current Sense Amplifier with Monitor
• Wide Input Voltage Range: 3.4V to 42V
• Ultralow Quiescent Current Burst Mode® Operation:
  2.5μA I_Q Regulating 12V_IN to 3.3V_OUT
  Output Ripple < 10mV_P-P
• High Efficiency Synchronous Operation:
  96% Efficiency at 1A, 5V_OUT from 12V_IN
  94% Efficiency at 1A, 3.3V_OUT from 12V_IN
• Fast Minimum Switch-On Time: 50ns
• Low Dropout Under All Conditions: 200mV at 1A
• Allows Use Of Small Inductors
• Low EMI
• Adjustable and Synchronizable: 200kHz to 2.2MHz
• Current Mode Operation
• Accurate 1V Enable Pin Threshold
• Internal Compensation
• Output Soft-Start and Tracking
• Small Thermally Enhanced 3mm × 5mm 24-Lead QFN Package

Typical Application

Description

The LT®8611 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 10mV_P-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 V_IN 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 V_OUT 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.