BQ24090_12 Datasheet, PDF(13/34 Page) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger

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BQ24090_12 Datasheet, PDF (13/34 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger

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www.ti.com

bq24090, bq24091

bq24092, bq24093

bq24095

SLUS968D â JANUARY 2010 â REVISED DECEMBER 2012

FUNCTIONAL GENERAL DESCRIPTION

The bq2409x is a highly integrated family of single cell Li-Ion and Li-Pol chargers. The charger can be used to

charge a battery, power a system or both. The charger has three phases of charging: Pre-charge to recover a

fully discharged battery, fast-charge constant current to supply the buck charge safely and voltage regulation to

safely reach full capacity. The charger is very flexible, allowing programming of the fast-charge current and Pre-

charge/Termination Current. This charger is designed to work with a USB connection or Adaptor (DC out). The

charger also checks to see if a battery is present.

The charger also comes with a full set of safety features: JEITA Temperature Standard, Over-Voltage Protection,

DPM-IN, Safety Timers, and ISET short protection. All of these features and more are described in detail below.

The charger is designed for a single power path from the input to the output to charge a single cell Li-Ion or Li-

Pol battery pack. Upon application of a 5VDC power source the ISET and OUT short checks are performed to

assure a proper charge cycle.

If the battery voltage is below the LOWV threshold, the battery is considered discharged and a preconditioning

cycle begins. The amount of precharge current can be programmed using the PRE-TERM pin which programs a

percent of fast charge current (10 to 100%) as the precharge current. This feature is useful when the system load

is connected across the battery âstealingâ the battery current. The precharge current can be set higher to account

for the system loading while allowing the battery to be properly conditioned. The PRE-TERM pin is a dual

function pin which sets the precharge current level and the termination threshold level. The termination "current

threshold" is always half of the precharge programmed current level.

Once the battery voltage has charged to the VLOWV threshold, fast charge is initiated and the fast charge current

is applied. The fast charge constant current is programmed using the ISET pin. The constant current provides the

bulk of the charge. Power dissipation in the IC is greatest in fast charge with a lower battery voltage. If the IC

reaches 125Â°C the IC enters thermal regulation, slows the timer clock by half and reduce the charge current as

needed to keep the temperature from rising any further. Figure 18 shows the charging profile with thermal

regulation. Typically under normal operating conditions, the ICâs junction temperature is less than 125Â°C and

thermal regulation is not entered.

Once the cell has charged to the regulation voltage the voltage loop takes control and holds the battery at the

regulation voltage until the current tapers to the termination threshold. The termination can be disabled if desired.

The CHG pin is low (LED on) during the first charge cycle only and turns off once the termination threshold is

reached, regardless if termination, for charge current, is enabled or disabled.

Further details are mentioned in the Operating Modes section.

VO(REG)

IO(OUT)

FAST-CHARGE

CURRENT

PRE-CHARGE

CURRENT AND

TERMINATION

THRESHOLD

VO(LOWV)

Pre-

Conditioning

Phase

Thermal

Regulation

Phase

Current

Regulation

Phase

Voltage Regulation and

Charge Termination

Phase

Battery

Voltage,

V(OUT)

Battery Current,

I(OUT)

Charge

Complete

Status,

Charger

Off

IO(PRECHG)

DONE

I(TERM)

T(THREG)

Temperature, Tj

T(PRECHG)

T(CHG)

Figure 18. Charging Profile With Thermal Regulation

DONE

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Product Folder Links: bq24090 bq24091 bq24092 bq24093 bq24095

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