Ride-through IC provides 1A of uninterrupted output current

The device includes all functions necessary to provide seamless charging of a supercapacitor (or other storage element), including the monitoring of V_IN, V_OUT 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.

The LTC3355 uses a 1A programmable constant-current/constant-voltage (CC/CV) linear charger powered from V_OUT to charge a single supercapacitor, electrolytic capacitor or NiMH battery. A thermal regulation loop maximizes charge current while limiting the die temperature to 110°C. When the V_IN 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 V_OUT. Backup power can be delivered to V_OUT with capacitor voltages as low as 0.5V. The device has programmable boost, charger and V_IN current limits. Other features include a V_IN power fail indicator, VCAP power good indicator, and V_OUT 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.