LTC3351 - Hot Swappable Supercapacitor Charger, Backup Controller and System Monitor
Datasheet Documentation


Typical Application

LTC3351 Typical Application
LTC3351 Typical Application


The LTC®3351 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 x 7mm x 0.75mm QFN surface mount package.


4x7 QFN-44

LTC3351 Package Drawing
LTC3351 Package Drawing
Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price
LTC3351IUFF#TRPBF QFN 44 I $8.35 $5.86
LTC3351IUFF#PBF QFN 44 I $8.29 $5.80
LTC3351EUFF#TRPBF QFN 44 E $7.56 $5.31
LTC3351EUFF#PBF QFN 44 E $7.50 $5.25
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.