BQ24901 Status: ACTIVE

Product Information

Features

• Designed for Off-Line Charger Design for Single-Cell Li-Ion Packs
• Provides Control Feedback to a Primary-Side Controller
• Robust Battery Insertion and Removal Detection
• Charge Current and Voltage Regulation Feedback to Primary-Side for High-Accuracy Charging
• Charge Termination by Minimum Current and Time
• Pre-Charge Conditioning Regulator with Safety Timer
• Charge Status Outputs for LED or Host Processor Interface Indicates Charge-in-Progress, Charge Completion, and Fault Conditions
• Temperature Monitoring Before and During Charge
• Short-Circuit Protection
• Small, 14-Pin TSSOP Package
• APPLICATIONS
  • Cradle Chargers for Digital Cameras
  • Desktop Chargers
  • Handheld Devices

Description

The bq24901 Li-Ion charge management devices are designed specifically for off-line charger applications. The bq24901 resides on the secondary-side of the transformer and provides the control feedback to a variety of primary side controllers. The bq24901 offers current or voltage regulation feedback, temperature monitoring, charge status, and adjustable charge termination, in a single monolithic device. During battery-absent or charge-complete conditions, the bq24901 continuously regulates the secondary-side voltage, used as V_CC supply to the device.

The bq24901 features a time-limited preconditioning phase to condition deeply discharged cells. The pre-conditioning phase is achieved by linear regulation in the secondary side. Following preconditioning, the bq24901 regulates the charge current to the value set by the external current sense resistor. Once the battery reaches the charge voltage, the voltage regulation loop takes over and completes the charge cycle. The accuracy of the voltage regulation is better than ±30mV. Charge is terminated based on minimum current. The minimum current level is set through TADJ pin. An internal five-hour charge timer provides a backup for charge termination.

The bq24901 is designed to reliably detect battery insertion and removal conditions, including packs with open protectors. Other standard features include a recharge feature activated when the battery voltage falls below the V_RCH threshold.

In addition to the standard features, the bq24901 offers battery temperature monitoring and status display. The temperature-sense circuit continuously measures battery temperature using an external thermistor and suspends charge until the battery temperature is within the user-defined thresholds. The STAT pins indicate conditions of operation of the charger. These outputs can be used to drive an LED or interface to a host microcontroller.