BQ2057T Status: ACTIVE

Product Information

Features

• Ideal for Single (4.1 V or 4.2 V) and Dual-Cell (8.2 V or 8.4 V) Li-Ion or Li-Pol Packs
• Requires Small Number of External Components
• 0.3 V Dropout Voltage for Minimizing Heat Dissipation
• Better Than ±1% Voltage Regulation Accuracy With Preset Voltages
• AutoComp™ Dynamic Compensation of Battery Pack’s Internal Impedance to Reduce Charge Time
• Optional Cell-Temperature Monitoring Before and During Charge
• Integrated Voltage and Current Regulation With Programmable Charge-Current and High-or Low-Side Current Sensing
• Integrated Cell Conditioning for Reviving Deeply Discharged Cells and Minimizing Heat Dissipation During Initial Stage Of Charge
• Charge Status Output for Single or Dual Led or Host Processor Interface
• Automatic Battery-Recharge Feature
• Charge Termination by Minimum Current
• Automatic Low-Power Sleep Mode When V_CC Is Removed
• EVMs Available for Quick Evaluation
• Packaging: 8-Pin SOIC, 8-Pin TSSOP, 8-Pin MSOP

AutoComp is a trademark of Texas Instruments.

Description

The BENCHMARQ bq2057 series advanced Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) linear charge-management ICs are designed for cost-sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery conditioning, temperature monitoring, charge termination, charge-status indication, and AutoComp charge-rate compensation in a single 8-pin IC. MSOP, TSSOP, and SOIC package options are offered to fit a wide range of end applications.

The bq2057 continuously measures battery temperature using an external thermistor. For safety, the bq2057 inhibits charge until the battery temperature is within user-defined thresholds. The bq2057 then charges the battery in three phases: conditioning, constant current, and constant voltage. If the battery voltage is below the low-voltage threshold, V_(min), the bq2057 precharges using a low current to condition the battery. The conditioning charge rate is approximately 10% of the regulation current. The conditioning current also minimizes heat dissipation in the external pass-element during the initial stage of the charge. After conditioning, the bq2057 applies a constant current to the battery. An external sense-resistor sets the current. The sense-resistor can be on either the high or low side of the battery without additional components. The constant-current phase continues until the battery reaches the charge-regulation voltage.

The bq2057 then begins the constant-voltage phase. The accuracy of the voltage regulation is better than ±1% over the operating-temperature and supply-voltage ranges. For single and dual cells, the bq2057 is offered in four fixed-voltage versions: 4.1 V, 4.2 V, 8.2 V, and 8.4 V. Charge stops when the current tapers to the charge termination threshold, I_(TERM). The bq2057 automatically restarts the charge if the battery voltage falls below the V_(RCH) threshold.

The designer also may use the AutoComp feature to reduce charging time. This proprietary technique allows safe and dynamic compensation for the internal impedance of the battery pack during charge.