Summary of LTC4121/LTC4121-4.2 – 40V 400mA Synchronous Step-Down Battery Charger
The LTC4121 is a 400mA CC/CV synchronous step-down battery charger designed for high efficiency (up to 95%) and wide input voltage ranges (4.4V to 40V). It features temperature-compensated MPPT regulation, making it ideal for solar applications with high-impedance sources like solar panels. The device supports Li-Ion/Polymer batteries via the fixed 4.2V variant or multiple chemistries through its programmable float voltage option.
Parts used in the LTC4121 Battery Charger Project:
- LTC4121 IC
- LTC4121-4.2 IC
- Solar Panel (High Impedance Input Source)
- Li-Ion/Polymer Battery
- External Resistor (for programming charge current)
- 16-Lead QFN Package (3mm × 3mm)
Features
- 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
Description
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
-
What is the maximum charge current of the LTC4121?
The LTC4121 supports a programmable charge current ranging from 50mA to 400mA. -
How does the LTC4121 maintain maximum power transfer?
It regulates its input voltage to a programmable percentage of the input open-circuit voltage using temperature-compensated MPPT. -
Can the LTC4121 be used with solar panels?
Yes, it is suitable for high impedance input sources such as solar panels to maintain maximum power transfer. -
What is the input voltage range supported by the device?
The device supports a wide input voltage range from 4.4V to 40V. -
How do you program the charge current?
An external resistor is used to program the charge current up to 400mA. -
Does the LTC4121 support multiple battery chemistries?
Yes, the LTC4121 with adjustable float voltage (3.5V to 18V) is suitable for several battery chemistries. -
What is the efficiency rating of the LTC4121?
The device offers high efficiency of up to 95%. -
Which version is specifically for Li-Ion/Polymer batteries?
The LTC4121-4.2 is suitable for charging Li-Ion/Polymer batteries with a fixed 4.2V float voltage.
