Features

• Wide V_IN Range: 4V to 38V
• ±1% 0.8V 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 Into Pre-Biased Output
• Optimized for High Step-Down Ratios
• Pin Compatible with the LTC1778 (No EXTV_CC Pin)
• Power Good Output Voltage Monitor
• Dual N-Channel MOSFET Synchronous Drive
• Adjustable Switching Frequency
• Programmable Current Limit with Foldback
• Output Overvoltage Protection
• Small 16-Pin Narrow SSOP Package

Typical Application

Description

The LTC3878 is a synchronous step-down switching DC/DC 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. The LTC3878 is pin compatible with the LTC1778 in applications that do not use EXTV_CC while offering better efficiency. Consult with the factory to verify compatibility.

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. Soft-start capability for supply sequencing is accomplished through an external timing capacitor. The current limit is user programmable.

The LTC3878 allows operation from 4V to 38V at the input and from 0.8V to 90% V_IN at the output. The LTC3878 is available in a small 16-pin narrow SSOP package.