ICs protect portable devices during battery charging.
September 12, 2007 -
Featuring input over-voltage threshold of 5.85 V, model bq24314 programmable battery charger front-end IC protects lithium battery when charger circuit fails due to fault condition and can report status of fault to host or application processor. Model bq24316 supports up to 6.8 V threshold. Both 2 x 2 mm safety circuits protect cell phones and other portable electronic devices from input over-voltage, over-current, and battery over-voltage conditions.
TI Power Management Technology Increases System Safety When Charging a Cell Phone
Innovative Charger Front-End Circuits Add Protection from Input Over-Voltage, Over-Current and Battery Over-Voltage Conditions
DALLAS (September 5, 2007) -- Texas Instruments (TI) (NYSE: TXN) introduced today a family of battery charger front-end integrated circuits, which dramatically increases protection when charging a cell phone or other portable electronic device. The 2 mm x 2 mm 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. See: www.ti.com/bq24314-pr.
"Adding power protection to a handheld device helps safeguard end users against accidental fault conditions, which reduces the number of customer end-equipment returns," said Masoud Beheshti, director of TI's battery charge management business. "This unique charger front-end circuit provides three solid levels of protection to provide the maximum amount of safety when charging a handheld device."
The first member of TI's new 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 new DM355 processor based on DaVinci(TM) technology (see: www.ti.com/dm355pr) or an application processor from the OMAP(TM) 3 product family, allowing the host processor to apply additional corrective actions.
Input Over-Voltage Challenges
Input over-voltage conditions are caused by steady-state or transient voltage events, such as "hot-plugging" a charged adapter; using a non-regulated or incorrect adapter; or load transients. Any of these events can increase or "spike" the voltage applied to the device and potentially damage the host system. The bq24314 detects the over-voltage level and effectively 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.
High-Input Over-Current Protection
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. Often there is no protection from pulling excessive current from the adapter to the system. 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.
Battery Over-Voltage Protection
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. Because of this, portable designers currently seek redundant safety measures to ensure battery safety and compliance. 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.
Key Technical Features of the bq24314 & bq24316:
Provides protection for three variables: input over-voltage, input over-current and battery over-voltage
30-V maximum input voltage
Integrated power FET and current sensor that supports up to 1.5-A input current
Less than 1 µs response time against input over-voltage
Input over-voltage protection threshold at 5.85 V (bq24314) or 6.8 V (bq24316)
High immunity against false triggering due to current transients
Status indication - fault condition
Thermal shutdown
Pricing and Availability
The bq24314 and bq24316 are available today in volume from TI and its authorized distributors. Both devices come in a tiny 8-pin, 2 mm x 2 mm small-outline, no-lead (SON) package. Suggested retail pricing for both in 1,000-piece quantities is $0.75. Evaluation modules of the bq24314 and bq24316, design application notes and TI's easy-to-use online power management selection tool are available through power.ti.com.
In the fourth quarter of 2007, TI plans to introduce new bq24300 charger front-end protection ICs. Featuring a fixed input over-current protection threshold of 300mA, and input over-voltage protection threshold at 10.5 V, the bq24300 devices target low-power applications, like Bluetooth headsets. The bq24300 acts as a linear regulator by managing the output to 5.5 V (or 4.5 V with the bq24304) for voltages up to the input over-voltage threshold. Additionally, a bq24300 circuit can protect against a faulty adaptor, by causing a reverse voltage at the input with an optional external P-Channel FET.
About Texas Instruments
Texas Instruments Incorporated provides innovative DSP and analog technologies to meet our customers' real world signal processing requirements. In addition to Semiconductor, the company includes the Education Technology business. TI is headquartered in Dallas, Texas, and has manufacturing, design or sales operations in more than 25 countries.
Texas Instruments is traded on the New York Stock Exchange under the symbol TXN. More information is located on the World Wide Web at: http://www.ti.com
Please refer all reader inquiries to:
Texas Instruments Incorporated
Semiconductor Group, SC-07138
Literature Response Center
14950 FAA Blvd.
Ft. Worth, TX 76155
1-800-477-8924
Trademarks
DaVinci and OMAP are trademarks of Texas Instruments. All other trademarks and registered trademarks are the property of their respective owners.
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