LTC3552-1 - Standalone Linear Li-Ion Battery Charger and Dual Synchronous Buck Converter


  • Programmable Charge Current Up to 950mA
  • Complete Linear Charger and Dual DC/DC Regulator
  • Dual Fixed Outputs:
     1.8V at 800mA
     1.575V at 400mA
  • No MOSFET, Sense Resistor or Blocking Diode Required
  • Thermal Regulation Maximizes Charge Rate Without Risk of Overheating*
  • Charges Directly from a USB Port
  • Programmable Charge Current Termination
  • Preset 4.2V Charge Voltage with ±1% Accuracy
  • Charge Current Monitor Output for Gas Gauging
  • Automatic Recharge
  • Charge Status Output
  • “Power Present” Output
  • Soft-Start Limits Inrush Current
  • Low Quiescent Current Buck Converter (40μA)
  • Current Mode Operation, Constant Frequency (2.25MHz)
  • Low Profi le (5mm × 3mm × 0.75mm) DFN Package

Typical Application

LTC3552-1 Typical Application
LTC3552-1 Typical Application


The LTC3552-1 is a complete constant-current/constantvoltage linear charger and dual fi xed output DC/DC converter for single cell lithium-ion batteries. Its DFN package and low external component count make the LTC3552-1 ideally suited for portable applications. Furthermore, the LTC3552-1 is designed to work within USB power specifi cations.

No external sense resistor or external blocking diode are required due to the internal MOSFET architecture. The charge voltage is fixed at 4.2V and the charge current is programmed with a resistor. The charge cycle terminates when the charge current drops below the programmed termination threshold after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the LTC3552-1 enters a low current state dropping the battery drain current to less than 2μA. Thermal regulation maximizes charge rate without risk of overheating.

The synchronous step-down switching regulators generate fi xed output voltages of 1.8V and 1.575V. The switching frequency is set at 2.25MHz, allowing the use of small surface mount inductors and capacitors.

LTC3552 Adjustable (0.6V to 5V)
LTC3552-1 1.8V & 1.575V


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
LTC3552EDHC-1#PBF 5x3 DFN-16 DHC E 05-08-1706 Yes
LTC3552EDHC-1#TRPBF 5x3 DFN-16 DHC E 05-08-1706 Yes

LTC3552-1 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
LTC3552EDHC-1#PBF 5x3 DFN-16 E $3.29 $2.30 Yes
LTC3552EDHC-1#TRPBF 5x3 DFN-16 E $2.36 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.

Click here to view our complete list of demo boards


  • Cellular Telephones, PDAs, MP3 Players
  • Bluetooth Applications

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Design Tools


LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

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