35V hot swappable supercapacitor backup power controller

     Analog Devices(ADI) announced the introduction of the LTC3351 from Power byLinearTM, a supercapacitor charger and backup power controller IC that includes hot-swapable front end protection and all necessary features to provide a complete, standalone, capacitor-based backup power solution. The LTC3351's integrated hot-swap controller and circuit breaker use n-channel MOSFETs to provide a low-loss path from input to output and reduce inrush current through reentry current limitation.

     The device provides reliable, short-term uninterruptible power in the event of a primary power failure and is suitable for solid-state drive (SSD) and non-volatile dual-in-line memory module (NVDIMM) data backup, power failure alarm in medical and industrial applications, and "dying gasp" power failure indicators. The LTC3351 provides PowerPath4 control, capacitor stack charging and balancing, protection, and capacitor health monitoring. Other applications include high-current 12V through-flow power supplies and short-term uninterruptible power supplies (UPS) for servers, mass storage and high-availability systems

     The LTC3351 has an input voltage range of 4.5V to 35V and charge/backup current capability of over 10A. The device also provides balance and overvoltage protection for series stacks containing 1 to 4 supercapacitors. The LTC3351's synchronous step-down controller charges a stack of capacitors with constant current/constant voltage up to 5V per capacitor. In backup mode, the buck converter operates in reverse as a synchronous boost DC/DC, transferring power from the supercapacitor stack to the backup power system. The hot-swappable controller provides programmable UV/OV thresholds, PCIe compatible start timing, and precision threshold/retry inputs.

     The LTC3351 includes a precise 16-bit analog-to-digital converter (ADC) that continuously monitors input and output voltage and current. In addition, the internal measurement system monitors backup capacitor related parameters, including capacitor stack voltage, capacitance, and stack ESR(equivalent series resistance) to ensure adequate energy storage and power supply during backup mode. By monitoring the actual capacitance of the backup supercapacitor, the LTC3351 allows the system to set the capacitor voltage to a minimum while maintaining the required backup energy, thereby extending the life of the capacitor. All system parameters and fault status can be monitored through a 2-wire I2C interface, and alarm levels can be set to alert the system to sudden changes in these measurement parameters.