BQ24901PWRG4

BQ24901PWRG4 FEATURES

BQ24901PWRG4 DESCRIPTION

The bq24901 Li-Ion charge management devicesare designed specifically for off-line chargerapplications. The bq24901 resides onthesecondary-side of the transformer and providesthe control feedback to a variety of primary sidecontrollers. The bq24901 offers current or voltageregulation feedback, temperature monitoring,charge status, and adjustable charge termination,in asingle monolithic device. Duringbattery-absent or charge-complete conditions,the bq24901thecontinuouslysecondary-side voltage, used as VCC supply tothe device.regulatesthe bq24901 regulatesThe bq24901 features a time-limited precon–ditioning phase to condition deeply dischargedcells. The pre-conditioning phase is achieved bylinear regulation in the secondary side. Followingpreconditioning,thecharge current to the value set by the externalcurrent sense resistor. Once the battery reachesthe charge voltage, the voltage regulation looptakes over and completes the charge cycle. Theaccuracy of the voltage regulation is better than±30mV. Charge is terminated based on minimumcurrent. The minimum current level is set throughTADJ pin. An internal five-hour charge timerprovides a backup for charge termination.The bq24901 is designed to reliably detect batteryinsertion and removal conditions, including packswith open protectors. Other standard featuresinclude a recharge feature activated when thebattery voltage falls below the VRCH threshold.

BQ24901PWRG4 APPLICATIONS

BQ24901PWRG4 DESCRIPTION (continued)

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