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| BQ24040 Datasheet, PDF (15/31 Pages) Texas Instruments – 800mA Single-Input Single Cell Li-Ion Battery Charger With Auto Start | |||
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bq24040
bq24041
www.ti.com.................................................................................................................................... SLUS941A â SEPTEMBER 2009 â REVISED SEPTEMBER 2009
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)
T(THREG)
Temperature, Tj
DONE
I(TERM)
0A
T(PRECHG)
T(CHG)
Figure 23. Charging Profile With Thermal Regulation
DONE
DETAILED FUNCTIONAL DESCRIPTION
Power-Down or Undervoltage Lockout (UVLO)
The bq2404x family is in power down mode if the IN pin voltage is less than UVLO. The part is considered
âdeadâ 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.
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 24.
Sleep Mode
If the IN pin voltage is between than VOUT+VDT 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 25
New Charge Cycle
A new charge cycle is started when a good power source is applied, performing a chip disable/enable (TS
pin/BAT_EN), exiting Termination and Timer Disable Mode (TTDM), detecting a battery insertion or the OUT
voltage dropping below the VRCH threshold. The CHG pin is active low only during the first charge cycle,
therefore exiting TTDM or a dropping below VRCH will not turn on the CHG pin FET, if the CHG pin is already
high impedance.
Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): bq24040 bq24041
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