LT3651EUHE-4.2

Product Overview

Category

LT3651EUHE-4.2 belongs to the category of integrated circuits (ICs) specifically designed for battery charging applications.

Use

This product is primarily used for charging single-cell lithium-ion/polymer batteries in various portable electronic devices such as smartphones, tablets, and wearable devices.

Characteristics

• Input Voltage Range: 4V to 32V
• Charge Current: Up to 2A
• Programmable Charge Current Limit
• Constant Voltage/Constant Current Operation
• Thermal Regulation Maximizes Charging Rate without Overheating
• Automatic Recharge
• Battery Temperature Monitoring
• Reverse Battery Protection
• Low Shutdown Current: <1µA
• Small Package Size: 3mm x 3mm QFN

Package

The LT3651EUHE-4.2 is available in a compact 16-pin QFN package.

Essence

The essence of LT3651EUHE-4.2 lies in its ability to efficiently charge lithium-ion/polymer batteries while providing various protection features and flexibility in terms of charge current programming.

Packaging/Quantity

The product is typically supplied in tape and reel packaging, with a quantity of 250 units per reel.

Specifications

• Input Voltage Range: 4V to 32V
• Charge Voltage: 4.2V
• Charge Current: Up to 2A
• Charge Termination Current: 10% of Programmed Charge Current
• Charge Accuracy: ±0.5%
• Operating Temperature Range: -40°C to 85°C
• Shutdown Current: <1µA
• Package Type: 16-Pin QFN

Detailed Pin Configuration

1. VIN: Input Voltage Pin
2. GND: Ground Pin
3. BAT: Battery Connection Pin
4. ISET: Charge Current Programming Pin
5. PROG: Programming Pin for Various Features
6. STAT: Status Indicator Pin
7. TS: Battery Temperature Sense Pin
8. VFB: Feedback Voltage Pin
9. SS: Soft-Start Capacitor Pin
10. FLT: Fault Indicator Pin
11. PGND: Power Ground Pin
12. ILIM: Input Current Limit Programming Pin
13. EN: Enable Pin
14. FB: Feedback Pin
15. VCC: Supply Voltage Pin
16. NC: No Connection

Functional Features

1. Programmable Charge Current: The charge current can be set using an external resistor connected to the ISET pin, allowing flexibility in charging different battery capacities.
2. Thermal Regulation: The LT3651EUHE-4.2 incorporates thermal regulation to maximize the charging rate without overheating, ensuring safe and efficient charging.
3. Automatic Recharge: After a battery is fully charged, the IC automatically enters a low-current standby mode. If the battery voltage drops below a certain threshold, it initiates another charging cycle.
4. Battery Temperature Monitoring: The TS pin allows monitoring of the battery temperature, enabling protection against over-temperature conditions during charging.
5. Reverse Battery Protection: The IC includes reverse battery protection, preventing damage to the circuitry in case of accidental battery polarity reversal.

Advantages and Disadvantages

Advantages

• Wide input voltage range allows compatibility with various power sources.
• High charge current capability enables fast charging of batteries.
• Small package size facilitates integration into space-constrained designs.
• Comprehensive protection features ensure safe charging and prevent damage to the battery and circuitry.

Disadvantages

• Limited to single-cell lithium-ion/polymer battery charging applications.
• Requires external components for complete charging circuit implementation.

Working Principles

The LT3651EUHE-4.2 operates as a constant voltage/constant current charger for single-cell lithium-ion/polymer batteries. It regulates the charging process by controlling the charge current and monitoring the battery voltage and temperature.

Upon connection to a power source, the IC starts in a pre-conditioning mode, where it charges the battery with a low current until the battery voltage reaches a specific threshold. It then transitions to the constant current charging mode, where the charge current is set according to the programming resistor connected to the ISET pin. Once the battery voltage reaches the programmed charge voltage (typically 4.2V), the IC switches to constant voltage mode, maintaining a constant voltage across the battery terminals while reducing the charge current.

During the charging process, the LT3651EUHE-4.2 continuously monitors the battery temperature through the TS pin. If the temperature exceeds a certain limit, the charging process is paused until the temperature drops to a safe level.

Detailed Application Field Plans

The LT3651EUHE-4.2 finds extensive application in various portable electronic devices that utilize single-cell lithium-ion/polymer batteries. Some of the common application fields include: