LTC3351

RECOMMENDED FOR NEW DESIGNS

Hot Swappable Supercapacitor Charger, Backup Controller and System Monitor

Analog Devices LTC3351 Product Info

10 February 2026 6

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 35V

V_IN: 4.5V to 35V, V_CAP(n): Up to 5V per Capacitor, Charge/Backup Current: >10A
Programmable Input Current Limit Prioritizes System Load Over Capacitor Charge Current
All N-FET Charger Controller and PowerPath^™ Controller
Compact 44-Lead 4mm × 7mm QFN Package

Part details & applications

The LTC3351 is a backup power controller that charges and monitors a series stack of one to four supercapacitors. The LTC3351’s synchronous step-down controller drives N-channel MOSFETs for constant current/constant voltage charging with programmable input current limit. In addition, the step-down converter 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. The LTC3351 is available in a thermally enhanced low profile 44-lead 4mm × 7mm × 0.75mm QFN surface mount package.

APPLICATIONS

Swappable PCIE Cards with NVM
High Current 12V Ride-Through UPS
Servers/Mass Storage/High Availability Systems

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