Features

• Wide V_IN Range: 4V to 38V
• ±1% 0.6V Voltage Reference
• Extremely Fast Transient Response
• t_ON(MIN): 43ns
• No RSENSE™ Valley Current Mode Control
• Stable with Low ESR Ceramic C_OUT
• Supports Smooth Start-Up in Pre-Biased Output
• Optimized for High Step-Down Ratios
• Adjustable Output Voltage Soft-Start or Tracking
• Power Good Output Voltage Monitor
• Dual N-Channel MOSFET Synchronous Drive
• Adjustable Switching Frequency
• Programmable Current Limit with Foldback
• Output Overvoltage Protection
• 16-Pin MSOP and 3mm × 3mm QFN Packages

Typical Application

Description

The LTC3879 is a synchronous step-down switching regulator controller optimized for high switching frequency and fast transient response. The constant on-time valley current mode architecture allows for a wide input range, including very low duty factor operation. No external sense resistor or slope compensation is required. System flexibility is offered through a user-programmable soft-start pin and independent RUN pin. The voltage ramping soft-start function can be programmed with a capacitor or made to track an external reference source.

Operating frequency is set by an external resistor and compensated for variations in V_IN to offer excellent line stability. Discontinuous mode operation provides high efficiency during light load conditions. A forced continuous control pin allows the user to reduce noise and RF interference. Safety features include output overvoltage protection and programmable current limit with foldback. The current limit is user programmable.

The LTC3879 allows operation from 4V to 38V at the input and from 0.6V to 90% V_IN at the output. The LTC3879 is
available in a small 16-pin thermally enhanced MSOP or 3mm × 3mm QFN packages.