Analog Devices Inc Analog Devices, Inc.

LTC3351 Hot Swappable Backup Supercapacitor Charger

Analog Devices' PMIC is designed for charging and monitoring of PCIe cards, high current UPS systems, and servers

Image of Analog Devices' LTC3351 Backup Supercapacitor ChargerAnalog Devices LTC3351 is a synchronous step-down controller that charges and monitors up to four supercapacitors at one time. This converter drives N-channel MOSFETs for constant current/constant voltage charging with programmable input current limit. In addition, the device runs in reverse as a step-up converter to deliver power from the supercapacitor stack to the backup supply rail. Internal balancers eliminate the need for external balance resistors and each capacitor has a shunt regulator for overvoltage protection. The LTC3351 monitors system voltages, currents, stack capacitance, and ESR which can all be read over the I2C/SMBus port. The hot swap controller uses N-channel MOSFETs for inrush control and a low loss path from the input to the output. The ideal diode controller uses an N-channel MOSFET for a low loss power path from the supercapacitors to the output. This device comes in a 44-pin QFN package that has an operating temperature of -40°C to +125°C. The LTC3351 is designed for hot swappable applications such as PCIe cards, high current UPS systems, and servers.

Image of Analog Devices' LTC3351 Schematic
   Image of Analog Devices' LTC3351 Example from 12 V
Features
  • Integrated hot swap controller with circuit breaker
  • High efficiency synchronous step-down CC/CV charging of one to four series supercapacitors
  • Step-up mode in backup provides greater utilization of stored energy in supercapacitors
  • 16-bit ADC for monitoring system voltages/currents, capacitance, and ESR
  • Programmable undervoltage and overvoltage thresholds to 35 V
  • Voltage supply: 4.5 V to 35 V
  • Temperature operating range: -40°C to +125°C
  • Package/case: 44-QFN
Applications
    
  • Swappable PCIe cards
  • High current 12 V UPS
  
  • Servers
  • Mass storage
Published: 2018-02-15

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