Uninterruptible power supply with application power failure alarm and dying gasp power failure indication

Analog Devices announces the Power by Linear LTC3351, a new supercapacitor charger and backup power controller IC that provides all the features necessary to provide a complete standalone capacitor-based backup power solution, including hot swap front-end protection.

The LTC3351's integrated hot swap controller and circuit breaker use N-channel MOSFETs to provide a low-loss power path from input to output, along with foldback current limiting to reduce inrush current.

The new product provides short-term, reliable uninterruptible power in the event of a main power failure for applications such as solid-state drive (SSD) and nonvolatile dual in-line memory module (NVDIMM) data backup, power failure alarms in medical and industrial applications, and 'dying gasp' power failure indicators.

The LTC3351 also offers a variety of features, including PowerPath control, capacitor stack charging and balancing, protection, and capacitor health monitoring. It is also ideal for applications such as high-current 12V ride-through power supplies, short-term UPSs for servers, and large-capacity and high-availability systems.

The LTC3351 supports a 4.5V to 35V input voltage range and over 10A of charge/backup current capability. It also provides balancing and overvoltage protection for stacked configurations of one to four supercapacitors. The LTC3351's synchronous step-down controller enables constant current (CC)/constant voltage (CV) sharing of the capacitor stack up to 5V per cell.

In backup mode, this step-down (buck) converter operates in reverse as a synchronous step-up (boost) DC/DC, supplying power from the supercapacitor stack to the system power supply to be backed up. The hot-swap controller provides programmable UV/OV thresholds, PCIe-compliant startup timing, and precision threshold/RETRY inputs.

The LTC3351 includes a high-accuracy 16-bit ADC that continuously monitors input and output voltages and currents. Furthermore, an internal measurement system monitors parameters related to the backup capacitors themselves, including capacitor stack voltage, capacitance, and stack ESR (equivalent series resistance), to ensure adequate energy storage and power delivery during the backup period.

By monitoring the actual capacitance of the backup supercapacitor, the LTC3351 extends capacitor life by allowing the system to set the capacitor voltage to its minimum value while maintaining the required backup energy level. All system parameters and fault conditions can be monitored via a 2-wire I2C interface, and alarm levels can be set to alert the system to abrupt changes in any of the measured parameters.