BQ24266_15 Datasheet, PDF (18/41 Pages) Texas Instruments – bq24266 3A, 30V Standalone Single-Input, Single-Cell Switchmode Li-Ion Battery Charger

bq24266
SLUSBY5F – JUNE 2014 – REVISED AUGUST 2015
Device Functional Modes (continued)
Regulation
Voltage
Precharge
Phase
Regulation
Current
V_SYS
(3.6V)
System Voltage
Current Regulation
Phase
V_BATSHORT
(3 V)
Battery
Voltage
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Voltage Regulation
Phase
Termination
I_BATSHORT
Charge Current
Linear Charge
50mA Linear Charge to Maintain
to Close Pack
Minimum
Protector
System
Voltage
Battery FET (Q3) is
ON
Battery
FET
is OFF
Figure 10. Typical Charging Profile of bq24266
7.4.4 Battery Charging Process
When the battery is deeply discharged or shorted, the bq24266 applies a I_BATSHRT current to close the battery
protector switch and bring the battery voltage up to acceptable charging levels. During this time, the battery FET
is off and the system output is regulated to V_SYSREG(LO). Once the battery rises above V_BATSHRT, the charge
current is regulated to the value set by ISET. The battery FET is linearly regulated to maintain the system voltage
at V_SYSREG(LO). Under normal conditions, the time spent in this region is a very short percentage of the total
charging time, so the linear regulation of the charge current does not affect the overall charging efficiency for
very long. If the die temperature does heat up, the thermal regulation loop reduces the input current to maintain a
die temperature at 125°C. If the current limit for the SYS output is reached (limited by the input current limit, V_IN-
DPM, or 100% duty cycle), the SYS output drops to the V_MINSYS output voltage. When this happens, the charge
current is reduced to ensure the system is supplied with all the current that is needed while maintaining the
minimum system voltage. If the charge current is reduced to 0mA, pulling further current from SYS causes the
output to fall to the battery voltage and enter supplement mode (see the “Dynamic Power Path Management”
section for more details).
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