LTC4091 - 36V Battery Charger and Power Backup Manager


  • Seamless Transition Between Primary Power Source and Li-Ion Battery
  • 2A High Voltage Step-Down Regulator with Adaptive Output Control
  • Internal 75mΩ Ideal Diode Plus Optional External Ideal Diode Controller Provides Low Loss PowerPathTM When Primary Supply Not Present
  • Wide Input Voltage Range: 6V to 36V (60V Abs Max)
  • 4.45V Max Output Voltage
  • Full Featured Li-Ion Battery Charger
  • Pin Selectable 4.1V and 4.2V Charge Voltage Options
  • Thermally Enhanced Low Profile (0.75mm) 6mm × 3mm 22-Lead DFN Package

Typical Application

LTC4091 Typical Application
LTC4091 Typical Application


The LTC4091 is a 36V Li-Ion battery charger and power backup manager. The integrated step-down switching regulator charges a battery from a primary power source while providing power to the load. If primary power is lost, the load is seamlessly transitioned to the backup Li-ion/ polymer battery. To protect sensitive downstream loads, the maximum output voltage is 4.45V.

The LTC4091 provides an adaptive output that tracks the battery voltage for high efficiency charging. The charge current is programmable and an end-of-charge status output (CHRG) indicates full charge. Also featured is a termination timer and an NTC thermistor input used to monitor battery temperature while charging.

During backup, an internal 75mΩ ideal diode connects the battery to the load. An optional external ideal diode FET driver is available to reduce the voltage drop even further. 4.1V or 4.2V battery charge voltages can be selected.


For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC4091EDJC#PBF 6x3 DFN-22 DJC E 05-08-1714 Yes
LTC4091EDJC#TRPBF 6x3 DFN-22 DJC E 05-08-1714 Yes
LTC4091IDJC#PBF 6x3 DFN-22 DJC I 05-08-1714 Yes
LTC4091IDJC#TRPBF 6x3 DFN-22 DJC I 05-08-1714 Yes

LTC4091 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC4091EDJC#PBF 6x3 DFN-22 E $4.64 $3.25 Yes
LTC4091EDJC#TRPBF 6x3 DFN-22 E $4.70 $3.31 Yes
LTC4091IDJC#PBF 6x3 DFN-22 I $4.71 $3.30 Yes
LTC4091IDJC#TRPBF 6x3 DFN-22 I $4.77 $3.36 Yes
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* 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.

Part Number Description Price Documentation
DC2558A LTC4091 Demo Board | 36V Battery Charger and Power Backup Manager Contact Factory
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Click here to view our complete list of demo boards


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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

  • LTspice - A powerful SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators
  • LTpowerCAD - A complete power supply selection, synthesis and design tool
  • LTpowerPlay - A development environment supporting Linear Technology's Digital Power System Management (PSM) products
  • PScope & QuikEval - USB-based product demonstration and data acquisition system for use with our ADCs, DACs, and more
  • Linduino - Arduino compatible system for developing and distributing firmware libraries and example code
  • LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
  • And More!

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