Features

• Wide V_IN Range: 4V to 36V
• Sense Resistor Optional
• True Current Mode Control
• 2% to 90% Duty Cycle at 200kHz
• t_ON(MIN)</=100ns
• Stable with Ceramic C_OUT
• Dual N-Channel MOSFET Synchronous Drive
• Power Good Output Voltage Monitor
• ±1% 0.6V Reference
• Adjustable Current Limit
• Adjustable Switching Frequency
• Programmable Soft-Start
• Output Overvoltage Protection
• Optional Short-Circuit Shutdown Timer
• Micropower Shutdown: I_Q </=30µA
• Available in a 1mm 20-Lead TSSOP Package

Typical Application

Description

The LTC3778 is a synchronous step-down switching regulator controller for computer memory, automobile and other DC/DC power supplies. The controller uses a valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in V_IN and V_OUT.

Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces noise and RF interference, and can assist secondary winding regulation when the main output is lightly loaded. SENSE⁺ and SENSE^– pins provide true Kelvin sensing across the optional sense resistor or the sychronous MOSFET.

Fault protection is provided by internal foldback current limiting, an output overvoltage comparator, optional short-circuit shutdown timer and input undervoltage lockout. Soft-start capability for supply sequencing is accomplished using an external timing capacitor. The regulator current limit level is user programmable. Wide supply range allows operation from 4V to 36V at the input and from 0.6V up to (0.9)V_IN at the output.