Features

• V_IN Voltage Range: 3V to 20V
• V_OUT Voltage Range: 2.7V to 5V
• 1A Current Mode Buck Main Regulator
• 5A Boost Backup Regulator Powered from Single Supercapacitor
• Boost Regulator Operates Down to 0.5V for Maximum Utilization of Supercapacitor Energy
• Programmable Supercapacitor Charge Current to 1A with Overvoltage Protection
• Charger Supports Single Cell CC/CV Battery Charging
• Programmable V_IN Current Limit
• Programmable Boost Current Limit
• V_IN Power Fail Indicator
• V_CAP Power Good Indicator
• V_OUT Power On Reset Output
• Compact 20-Lead 4mm × 4mm QFN Package

Typical Application

Description

The LTC®3355 is a complete input power interrupt ridethrough DC/DC system. The part charges a supercapacitor while delivering load current to V_OUT, and uses energy from the supercapacitor to provide continuous V_OUT backup power when V_IN power is lost. The LTC3355 contains a nonsynchronous constant frequency current mode monolithic 1A buck switching regulator to provide a 2.7V to 5V regulated output voltage from an input supply of up to 20V.

A 1A programmable CC/CV linear charger charges the supercapacitor from V_OUT. When the V_IN supply drops below the PFI threshold, the devices’s constant frequency nonsynchronous current mode 5A boost switching regulator delivers power from the supercapacitor to V_OUT. A thermal regulation loop maximizes charge current while limiting the die temperature to 110°C. The IC has boost, charger and VIN programmable current limits. The LTC3355 is available in a 20-lead 4mm × 4mm QFN surface mount package.