2.5A backup power manager for two supercapacitors

August 10, 2018 // By Nick Flaherty
Analog Devices has launched a complete supercapacitor backup power management system for 2.9V to 5.5V supply rails that must be kept active during a main power failure.  Supercapacitors have higher power density than batteries, making them ideal for systems requiring high peak power backup for short periods of time.

The Power by Linear LTC4041 uses an on-chip bidirectional synchronous converter to provide high efficiency step-down supercapacitor charging, as well as high current, high efficiency boost backup power. When external power is available, the device operates as a step-down battery charger for one or two supercapacitor cells while giving preference to the system load. 

When the input supply drops below the adjustable power-fail input (PFI) threshold, the LTC4041 switches to step-up regulator operation, capable of delivering up to 2.5A to the system load from the supercapacitor. During a power fail event, the device’s PowerPath control provides reverse blocking and a seamless switchover from input power to backup power. Typical applications include ride-through “dying gasp” supplies, high current ride-through 3V-5V uninterruptible power supplies (UPSs), power meters, industrial alarms, servers and solid-state drives.

The charger provides 6.5A switches for 2.5A backup from one supercapacitor or two in series, and the input current limiter prioritises the load over the charge current while a diode isolates the input during backup.

The LTC4041 includes an optional overvoltage protection (OVP) function using an external FET which can protect the IC from input voltages greater than 60V. An internal supercapacitor balancing circuit maintains equal voltages across each supercapacitor and limits the maximum voltage of each supercapacitor to a predetermined value. Its adjustable input current limit function enables operation from a current limited source while prioritizing system load current over battery charge current.  An external disconnect switch isolates the primary input supply from the system during backup. The device also includes input current monitoring, an input power fail indicator, and a system power fail indicator.

The LTC4041 is offered in a low profile (0.75mm) 24-lead 4mm x 5mm QFN package with backside metal pad for excellent thermal performance. The device operates from –40°C to 125°C, in both E and I grades. Pricing starts at $3.30.

www.analog.com/LTC4041


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