LTC4066 - USB Power Manager with Low-Loss Ideal Diode and Li-Ion Battery Charger


  • Seamless Transition Between Input Power Sources:
    Li-Ion Battery, USB and 5V Wall Adapter
  • Low Loss (50mΩ) Ideal Diode Path from BAT to OUT
  • Programmable Charge Current Detection (CHRG)
  • Load Dependent Charging Guarantees USB Input Current Compliance
  • Analog Gas Gauge Function
  • Charges Single Cell Li-Ion Batteries Directly from USB Port
  • Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating*
  • Selectable 100% or 20% Current Limit (e.g., 500mA/100mA)
  • Termination Timer Adapts to Actual Charge Current
  • Preset 4.2V Charge Voltage with 0.8% Accuracy (4.1V for LTC4066-1)
  • NTC Thermistor Input for Temperature Qualified Charging
  • Thin Profile (0.75mm) 24-Lead 4mm x 4mm QFN Package
  • Ultrathin Profile (0.55mm) 24-Lead 4mm x 4mm UTQFN Package (LTC4066 Only)

Typical Application

LTC4066 Typical Application
LTC4066 Typical Application


The LTC4066/LTC4066-1 are USB power managers and Li-Ion battery chargers designed to work in portable battery-powered applications. The parts control the total current used by the USB peripheral for operation and battery charging. The total input current can be limited to 100mA, 500mA or “unlimited” (i.e., above 2A). Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit.

The LTC4066/LTC4066-1 include a standalone constant-current / constant-voltage linear charger for single cell Li-ion batteries. The float voltage applied to the battery is held to a tight 0.8% tolerance, and charge current is programmable using an external resistor to ground. A programmable end-of-charge status output (CHRG) indicates full charge. BAT pin charge and discharge cur- rents can be monitored via an analog output (ISTAT). Total charge time is programmable by an external capacitor to ground. When the battery drops 100mV below the float voltage, automatic recharging of the battery occurs. Also featured is an NTC thermistor input used to monitor bat- tery temperature while charging.

The LTC4066/LTC4066-1 are available in a 24-pin thin profile (0.75mm) 4mm x 4mm QFN package. The LTC4066 is also available in a 24-pin ultrathin profile (0.55mm) 4mm x 4mm UTQFN package.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

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

Part Number Package Code Temp Package
LTC4066EPF#PBF 4x4 UTQFN-24 PF E 05-08-1748 Yes
LTC4066EPF#TRPBF 4x4 UTQFN-24 PF E 05-08-1748 Yes
LTC4066EUF-1#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC4066EUF-1#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC4066EUF#PBF 4x4 QFN-24 UF E 05-08-1697 Yes
LTC4066EUF#TRPBF 4x4 QFN-24 UF E 05-08-1697 Yes

LTC4066 Package Drawing
LTC4066 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
LTC4066EPF#PBF 4x4 UTQFN-24 E $3.36 $2.35 Yes
LTC4066EPF#TRPBF 4x4 UTQFN-24 E $2.41 Yes
LTC4066EUF-1#PBF 4x4 QFN-24 E $3.29 $2.30 Yes
LTC4066EUF-1#TRPBF 4x4 QFN-24 E $2.40 Yes
LTC4066EUF#PBF 4x4 QFN-24 E $3.29 $2.30 Yes
LTC4066EUF#TRPBF 4x4 QFN-24 E $2.40 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
DC848A LTC4066EUF | USB Power Manager and Li-Ion Charger $150.00
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  • Portable USB Devices
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  • Mulitple Input Chargers

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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
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