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Complete Ride-Through DC/DC IC Provides 1A of Uninterrupted Output Current from Main Input or Single Supercapacitor Backup Supply  

MILPITAS, CA - March 10, 2014 - Linear Technology Corporation introduces the LTC3355, a complete ride-through DC/DC system IC. The LTC3355 features a main buck regulator with a built-in boost converter for temporary backup, or ride-through, of VOUT during a sudden loss of VIN power from a single supercapacitor energy source. The device includes all functions necessary to provide seamless charging of a supercapacitor (or other storage element), including the monitoring of VIN, VOUT and VCAP and automatic switchover to backup power. The LTC3355’s nonsynchronous constant frequency current mode monolithic 1A buck switching regulator provides a 2.7V to 5V regulated output voltage from an input supply up to 20V. The device is ideal for ride-through, “dying gasp” or data backup supplies commonly used in power meters, industrial alarms and solid state drives.

Complete Ride-Through DC/DC System IC

The LTC3355 uses a 1A programmable constant-current/constant-voltage (CC/CV) linear charger powered from VOUT to charge a single supercapacitor, electrolytic capacitor or NiMH battery. thermal regulation loop maximizes charge current while limiting the die temperature to 110°C. When the VIN supply drops below the programmable power-fail comparator input (PFI) threshold, the device’s constant frequency nonsynchronous current mode 5A boost switching regulator delivers power from the supercapacitor to VOUT. Backup power can be delivered to VOUT with capacitor voltages as low as 0.5V. The device has programmable boost, charger and VIN current limits. Other features include a VIN power fail indicator, VCAP power good indicator, and VOUT power-on reset (POR) output.

The LTC3355 is available in a thermally enhanced 20-lead, low-profile (0.75mm) 4mm x 4mm QFN package. The device operates over a -40°C to 125°C junction temperature range and is available from stock. Pricing starts at $3.25 each for the E grade in 1,000-piece quantities. For more information, visit

Summary of Features: LTC3355

  • 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 x 4mm x 0.75mm QFN Package

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