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
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.
The LTC4121 and LTC4121-4.2 include an accurate RUN pin threshold, low voltage battery preconditioning and bad battery fault detection, timer termination, auto-recharge, and NTC temperature qualified charging. The FAULT pin provides an indication of bad battery or temperature faults.
Once charging is terminated, the LTC4121 signals end-ofcharge via the CHRG pin, and enters a low current SLEEP mode. An auto-restart feature starts a new charging cycle if the battery voltage drops by 2.2%.
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 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
|Buy Now • Request Samples|
Demo BoardsLinear 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.
|DC1977A-A||LTC4121EUD-4.2 Demo Board | 400mA Sync Buck Li Ion Battery Charger, VIN = 4.4V to 40V||$125.00|
|DC1977A-B||LTC4121EUD Demo Board | 400mA Synchronous Buck Battery Charger, VIN = 4.4V to 40V, VBAT = Adjustable||$125.00|
- Handheld Instruments
- Solar Powered Devices
- Industrial/Military Sensors and Devices
People Who Viewed This Product Also Viewed
- LT3652 - Power Tracking 2A Battery Charger for Solar Power
- LT8490 - High Voltage, High Current Buck-Boost Battery Charge Controller with Maximum Power Point Tracking (MPPT)
- LTC4020 - 55V Buck-Boost Multi-Chemistry Battery Charger
- LTC4120/LTC4120-4.2 - Wireless Power Receiver and 400mA Buck Battery Charger
- LT3652HV - Power Tracking 2A Battery Charger
- LTC4000 - High Voltage High Current Controller for Battery Charging and Power Management
- LTM8062 - 32VIN, 2A μModule (Power Module) Power Tracking Battery Charger
- LT1512 - SEPIC Constant-Current/Constant-Voltage Battery Charger
- LTC3105 - 400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up
- LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
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 IV - 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
- PScope & QuikEval - USB-based product demonstration and data acquisition system for use with our ADCs, DACs, and more
- Linduino - Arduino compatible system for developing and distributing firmware libraries and example code
- LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
- And More!