TI Power Management Technology Increases System Safety When Charging a Cell Phone

TI Power Management Technology Increases System Safety When Charging a Cell Phone

September 06, 2007

Innovative Charger Front-End Circuits Add Protection from
Input Over-Voltage, Over-Current and Battery Over-Voltage
Conditions 


    DALLAS, Sept. 6 /Xinhua-PRNewswire/ -- 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: http://www.ti.com/bq24314-pr
.

    (Logo:
http://www.xprn.com.cn/xprn/sa/20061107170439-20-min.jpg ) 
 

    "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: http://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 ¦Ìs 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 http://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 reverse
polarity caused by a faulty adaptor using an optional
external P-channel MOSFET.  

    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:	
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    DaVinci and OMAP are trademarks of Texas Instruments. 
All other trademarks and registered trademarks are the
property of their respective owners.



    For more information, please contact:

     Matt McKinney
     Texas Instruments
     Tel:   [phone]
     Email: [e-mail]

     Jacqi Moore
     Golin/Harris
     Tel:   [phone]
     Email: [e-mail]