LTC4009 - High Efficiency, Multi-Chemistry Battery Charger


  • General Purpose Battery Charger Controller
  • Efficient 550kHz Synchronous Buck PWM Topology
  • ±0.5% Output Float Voltage Accuracy
  • Programmable Charge Current: 4% Accuracy
  • Programmable AC Adapter Current Limit: 3% Accuracy
  • No Audible Noise with Ceramic Capacitors
  • Wide Input Voltage Range: 6V to 28V
  • Wide Output Voltage Range: 2V to 28V
  • Indicator Outputs for AC Adapter Present, Charging, C/10 Current Detection and Input Current Limiting
  • Analog Charge Current Monitor
  • Micropower Shutdown
  • Thermally Enhanced 20-Pin 4mm × 4mm × 0.75mm QFN Package

Typical Application

LTC4009 Typical Application
LTC4009 Typical Application


The LTC4009 is a constant-current/constant-voltage battery charger controller. It uses a synchronous quasiconstant frequency PWM control architecture that will not generate audible noise with ceramic bulk capacitors. Charge current is set by the combination of external sense, input and programming resistors. With no built-in termination, the LTC4009 family charges a wide range of batteries under external control.

The LTC4009 features a fully adjustable output voltage, while the LTC4009-1 and LTC4009-2 can be pin-programmed for lithium-ion/polymer battery packs of 1-, 2-, 3- or 4-series cells. The LTC4009-1 provides output voltage of 4.1V/cell, and the LTC4009-2 is a 4.2V/cell version.

The device includes AC adapter input current limiting which maximizes the charge rate for a fixed input power level. An external sense resistor programs the input current limit, and the ICL status pin indicates when the battery charge current is being reduced as a result of AC adapter current limiting.

The CHRG status pin is active during all charging modes, including special indication for low charge current.


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

Part Number Package Code Temp Package
LTC4009CUF-1#PBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009CUF-1#TRPBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009CUF-2#PBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009CUF-2#TRPBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009CUF#PBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009CUF#TRPBF 4x4 QFN-20 UF C 05-08-1710 RoHS
LTC4009IUF-1#PBF 4x4 QFN-20 UF I 05-08-1710 RoHS
LTC4009IUF-1#TRPBF 4x4 QFN-20 UF I 05-08-1710 RoHS
LTC4009IUF-2#PBF 4x4 QFN-20 UF I 05-08-1710 RoHS
LTC4009IUF-2#TRPBF 4x4 QFN-20 UF I 05-08-1710 RoHS
LTC4009IUF#PBF 4x4 QFN-20 UF I 05-08-1710 RoHS
LTC4009IUF#TRPBF 4x4 QFN-20 UF I 05-08-1710 RoHS

LTC4009 Package Drawing
LTC4009 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
LTC4009CUF-1#PBF 4x4 QFN-20 C $4.36 $3.05 Yes
LTC4009CUF-1#TRPBF 4x4 QFN-20 C $3.11 Yes
LTC4009CUF-2#PBF 4x4 QFN-20 C $4.36 $3.05 Yes
LTC4009CUF-2#TRPBF 4x4 QFN-20 C $3.11 Yes
LTC4009CUF#PBF 4x4 QFN-20 C $4.22 $2.95 Yes
LTC4009CUF#TRPBF 4x4 QFN-20 C $3.01 Yes
LTC4009IUF-1#PBF 4x4 QFN-20 I $5.00 $3.50 Yes
LTC4009IUF-1#TRPBF 4x4 QFN-20 I $3.56 Yes
LTC4009IUF-2#PBF 4x4 QFN-20 I $5.00 $3.50 Yes
LTC4009IUF-2#TRPBF 4x4 QFN-20 I $3.56 Yes
LTC4009IUF#PBF 4x4 QFN-20 I $4.86 $3.40 Yes
LTC4009IUF#TRPBF 4x4 QFN-20 I $3.46 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
DC1104A LTC4009CUF-1/-2 Demo Board | Multi-Chemistry, 2A Sync Buck Battery Charger, 1.35V ≤ VIN ≤ 20V $125.00
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Companion Boards

Part Number Description Price Documentation
DC1223A-B USB to SM-Bus/SPI Interface with Monitor $400.00
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Click here to view our complete list of demo boards


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