EA402143DDR

EA4021 is a highly integrated 28V 1A single-cell lithium-ion battery linear charge management controller. The charging process consists of three stages: trickle charge, constant current charge, and constant voltage charge, requiring no external sense resistors, isolation diodes, or MOSFETs. Thermal feedback is used to regulate the charge current, limiting the die temperature during high-power operation or excessive ambient temperature to maximize the charge rate without risk of overheating. The charge current can be set via an external resistor. After the final cutoff voltage is reached, EA4021 automatically terminates the charge cycle when the charge current drops to 1/10 of the programmed value. If the battery voltage falls below the internal recharge threshold, charging restarts automatically. EA4021 features a built-in battery reverse-polarity protection circuit; reversing the battery terminals will not damage the IC. EA4021 provides a charge indicator pin to indicate the charging status and a charge-complete indicator pin to indicate the full-charge status. The two pins work together and can also indicate other fault conditions. EA4021 is a standalone linear lithium-ion battery charger with thermal regulation, requiring one external 1% precision resistor to set the charge current. A normal charge cycle begins when the voltage at the VIN pin exceeds the UVLO threshold. If the battery voltage is below V_TRIKL, the device operates in trickle charge mode. The trickle charge current is 1/10 of the programmed value, effectively protecting the battery from damage and extending battery life. When the voltage at the BAT pin rises above V_TRIKL, the charger enters constant current mode, in which the charge current equals the programmed value. Once the voltage at the BAT pin reaches VFLOAT, the charger enters constant voltage mode and the charge current decreases. In constant voltage mode, the charge cycle ends once the charge current drops to 1/10 of the programmed value. After the charge cycle is complete and charging has ended, EA4021 continues to monitor the BAT voltage. Once the BAT voltage drops to 4.05V, it recharges the battery. EA4021 includes a soft-start circuit to reduce the impact of inrush current on the IC and battery at the start of a charge cycle. When the PROG pin is left floating, the charger enters shutdown mode. The PROG pin can be used as a chip enable pin. EA4021 monitors the input voltage through an internal UVLO circuit. When the VIN voltage falls below the UVLO voltage, the IC stops charging and remains in output shutdown mode. When VIN rises above the UVLO threshold, the IC exits undervoltage lockout and resumes normal operation. The UVLO circuit has a built-in 200mV hysteresis. In addition, to prevent reverse current in the power MOSFET, if VIN drops to within 50mV of the battery voltage, the UVLO circuit holds the IC in shutdown mode. The IC does not exit shutdown mode and resume normal operation until VIN rises to 200mV above the battery voltage. EA4021 monitors the VIN voltage through an internal OVLO circuit. When the VIN voltage exceeds the OVLO voltage, the IC stops charging and remains in output shutdown mode. When the VIN voltage drops below the OVLO threshold, the IC exits overvoltage lockout and resumes normal operation. The OVLO circuit has a built-in 400mV hysteresis. The EA4021 charging function can be manually disabled by pulling the CE pin low or disconnecting RPROG, and re-enabled by setting the CE pin HIGH or reconnecting RPROG. EA4021 features a temperature monitoring function to protect the battery from damage due to continued charging at excessively high or low temperatures. Battery temperature detection is achieved by monitoring the TEMP pin voltage, which is derived from a voltage divider formed by the NTC thermistor inside the battery and an external resistor. EA4021 compares the voltage VTEMP on the TEMP pin against the VLOW and VHIGH threshold voltages, and terminates the charging process when VTEMP > VHIGH or VTEMP < VLOW. The VLOW voltage equals 5% of VIN, and the VHIGH voltage equals 80% of VIN. When the TEMP pin is connected to GND or left floating, this function is disabled. EA4021 features battery reverse-polarity protection. When the battery is connected in reverse, EA4021 will not operate normally, no charge current will flow, a fault condition will be indicated, and the charge LED will flash once per second. When the battery is connected correctly, EA4021 automatically resumes normal operation and charges normally.