LTC3559/LT3559-1 - Linear USB Battery Charger with Dual Buck Regulators


Battery Charger
  • Standalone USB Charger
  • Up to 950mA Charge Current Programmable via Single Resistor
  • HPWR Input Selects 20% or 100% of Programmed Charge Current
  • NTC Input for Temperature Qualified Charging
  • Internal Timer Termination
  • Bad Battery Detection
  • CHRG indicates C/10 or Timeout
Buck Regulators
  • 400mA Output Current
  • 2.25MHz Constant Frequency Operation
  • Zero Current in Shutdown
  • Low Noise Pulse Skip Operation or Power Saving Burst Mode Operation
  • Low No Load Quiescent Current: 35μA
  • Available in a Low Profile Thermally Enhanced 16-Lead 3mm × 3mm QFN Package

Typical Application

LTC3559 Typical Application
LTC3559 Typical Application


The LTC3559/LTC3559-1 are USB battery chargers with dual high efficiency buck regulators. The parts are ideally suited to power single-cell Li-Ion/Polymer based handheld applications needing multiple supply rails.

Battery charge current is programmed via the PROG pin and the HPWR pin, with capability up to 950mA at the BAT pin. The battery charger has an NTC input for temperature qualified charging. The CHRG pin allows battery status to be monitored continuously during the charging process. An internal timer controls charger termination.

Each monolithic synchronous buck regulator provides up to 400mA of output current while operating at efficiencies greater than 90% over the entire Li-Ion/Polymer range. A MODE pin provides the flexibility to place both buck regulators in a power saving Burst Mode operation or a low noise pulse skip mode.

The LTC3559/LTC3559-1 are offered in a low profile thermally enhanced 16-lead (3mm × 3mm) QFN 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
LTC3559EUD-1#PBF 3x3 QFN-16 UD E 05-08-1691 Yes
LTC3559EUD-1#TRPBF 3x3 QFN-16 UD E 05-08-1691 Yes
LTC3559EUD#PBF 3x3 QFN-16 UD E 05-08-1691 Yes
LTC3559EUD#TRPBF 3x3 QFN-16 UD E 05-08-1691 Yes

LTC3559 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
LTC3559EUD-1#PBF 3x3 QFN-16 E $3.07 $2.15 Yes
LTC3559EUD-1#TRPBF 3x3 QFN-16 E $2.21 Yes
LTC3559EUD#PBF 3x3 QFN-16 E $3.07 $2.15 Yes
LTC3559EUD#TRPBF 3x3 QFN-16 E $2.21 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
DC1085A LTC3559EUD Demo Board | USB Li-Ion Linear Charger w/ Dual 400mA Buck Regulators $125.00
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Click here to view our complete list of demo boards


  • SD/Flash-Based MP3 Players
  • Low Power Handheld Applications

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Design Tools


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