LTC4121/LTC4121-4.2 – 40V 400mA Synchronous Step-Down Battery Charger


  • Wide Input Voltage Range: 4.4V to 40V
  • Temperature Compensated Input Voltage Regulation for Maximum Power Point Tracking (MPPT)
  • Adjustable Float Voltage 3.5V to 18V (LTC4121)
  • Fixed 4.2V Float Voltage Option (LTC4121-4.2)
  • High Efficiency: Up to 95%
  • 50mA to 400mA Programmable Charge Current
  • ±1% Feedback Voltage Accuracy
  • Programmable 5% Accurate Charge Current
  • Thermally Enhanced, Low Profile (0.75mm) 16-Lead (3mm × 3mm) QFN Package

Typical Application

LTC4121/LTC4121-4.2 - 40V 400mA Synchronous Step-Down Battery Charger


The LTC®4121 is a 400mA constant-current/constantvoltage (CC/CV) synchronous step-down battery charger. In addition to CC/CV operation, the LTC4121 regulates its input voltage to a programmable percentage of the input open-circuit voltage. This technique maintains maximum power transfer with high impedance input sources such as solar panels.

An external resistor programs the charge current up to 400mA. The LTC4121-4.2 is suitable for charging Li-Ion/ Polymer batteries, while the programmable float voltage of the LTC4121 is suitable for several battery chemistries.


For more detail: LTC4121/LTC4121-4.2 – 40V 400mA Synchronous Step-Down Battery Charger

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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