Battery charger with constant current mode

A battery charger in constant current (CC) mode supplies a fixed current to the battery regardless of its voltage (up to a safe limit).

Constant Current Mode Charging – Key Concepts

1. Operation Principle

• The charger regulates output current to a preset constant value (e.g., 1A).
• The battery voltage gradually increases as it charges.
• Once the battery voltage reaches a predefined voltage threshold, the charger usually transitions to constant voltage (CV) mode.

Voltage and Current Profile

• Current: Held constant.
• Voltage: Increases as battery charges.

Typical Charger Architecture in CC Mode

Input Stage:

• AC-DC or DC-DC converter
• EMI filter, rectifier

Power Conversion:

• Buck or buck-boost converter for regulating output.
• Controlled via feedback loop to maintain constant current.

Control Loop:

• Current feedback loop:
• Current is sensed (via shunt resistor or current sensor).
• Compared to a reference value.
• Error is processed by a PI/PID controller to adjust the duty cycle