20V 1A Buck DC/DC with Integrated SCAP Charger and Backup Regulator

The LTC3355 is a complete input power interrupt ride-through DC/DC system. The part charges a supercapacitor while delivering load current to VOUT, and uses energy from the supercapacitor to provide continuous VOUT backup power when VIN 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 VOUT. When the VIN supply drops below the PFI threshold, the devices’s constant frequency nonsynchronous current mode 5A boost switching regulator delivers power from the supercapacitor to VOUT. 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.

Applications

* Ride-Through “Dying Gasp” Supplies

* Power Meters/Industrial Alarms/Solid State Drives

* VIN Voltage Range: 3V to 20V* VOUT 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 VIN Current Limit* Programmable Boost Current Limit* VIN Power Fail Indicator* VCAP Power Good Indicator* VOUT Power On Reset Output* Compact 20-Lead 4mm × 4mm QFN Package