BQ24090_12 Datasheet, PDF (14/34 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger

bq24090, bq24091
bq24092, bq24093
bq24095
SLUS968D – JANUARY 2010 – REVISED DECEMBER 2012
DETAILED FUNCTIONAL DESCRIPTION
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Power-Down or Undervoltage Lockout (UVLO)
The bq2409x family is in power down mode if the IN pin voltage is less than UVLO. The part is considered
“dead” and all the pins are high impedance. Once the IN voltage rises above the UVLO threshold the IC will
enter Sleep Mode or Active mode depending on the OUT pin (battery) voltage.
Under Voltage Lockout (UVLO):
The bq2409x family is in power down mode if the IN pin voltage is less than V_UVLO. The part is considered “dead”
and all the pins are high impedance.
Power-up
The IC is alive after the IN voltage ramps above UVLO (see sleep mode), resets all logic and timers, and starts
to perform many of the continuous monitoring routines. Typically the input voltage quickly rises through the
UVLO and sleep states where the IC declares power good, starts the qualification charge at 100mA, sets the
input current limit threshold base on the ISET2 pin, starts the safety timer and enables the CHG pin. See
Figure 19.
Sleep Mode
If the IN pin voltage is between than V_OUT+V_DT and UVLO, the charge current is disabled, the safety timer
counting stops (not reset) and the PG and CHG pins are high impedance. As the input voltage rises and the
charger exits sleep mode, the PG pin goes low, the safety timer continues to count, charge is enabled and the
CHG pin returns to its previous state. See Figure 20
New Charge Cycle
A new charge cycle is started when a good power source is applied, performing a chip disable/enable (TS pin),
exiting Termination and Timer Disable Mode (TTDM), detecting a battery insertion or the OUT voltage dropping
below the V_RCH threshold. The CHG pin is active low only during the first charge cycle, therefore exiting TTDM or
a dropping below V_RCH will not turn on the CHG pin FET, if the CHG pin is already high impedance.
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