Dallas, Tex. Texas Instruments (TI) has introduced a family of battery charger front-end integrated circuits (ICs), which increases protection when charging a cell phone or other portable electronic device. The 2 x 2-mm bq243xx safety circuits protect a system from input over-voltage, over-current and battery over-voltage conditions, which may result from a power spike during charging, or a defective or incorrect wall adapter.
The first member of TI's bq243xx family of charger front-end circuits with integrated FETs, the bq24314, adds extra protection to a lithium battery when a charger circuit fails due to a fault condition. The protection IC can report status of the fault to the host processor, such as TI's DM355 processor based on its DaVinci technology or an application processor from the OMAP 3 product family, allowing the host processor to apply additional corrective actions.
Under input over-voltage conditions, the bq24314 detects the over-voltage level and disconnects the input to the charger to protect the device. The device features an input over-voltage threshold of 5.85 V. Another version of the circuit, the bq24316, supports up to 6.8 V. The device offers a less than 1 μs response time against an input over-voltage.
Input over-current conditions can occur in integrated power management devices that incorporate a battery charger, which have a direct connection from the input to the system's bus voltage. The programmable bq24314 limits the input current by sensing and regulating its integrated MOSFET to ensure the system does not pull an excessive amount of current. The integrated power FET and current sensor supports up to 1.5-A input current.
Potential hazardous events may occur if single-cell, Li-ion and Li-polymer batteries are over-charged beyond their float voltage, typically around 4.2 V, said TI. The bq24314 offers a second level of protection that helps monitor the battery's voltage and if an over-voltage is detected, interrupts the input charging source.
Pricing: Suggested retail pricing for the bq234314 and bq24316 is $0.75 in quantities of 1,000. Evaluation modules, design application notes and TI's online power management selection tool are available at www.power.ti.com
Availability: The bq24314 and bq24316 are available in volume from TI and its authorized distributors. Both devices come in an 8-pin, 2 x 2-mm small-outline, no-lead (SON) package.
Product information: bq24314
Texas Instruments Inc. , 1-800-477-8924, www.ti.com