Datasheet

Regulation
voltage
Charge Current
Battery
Voltage
V
SYS
System Voltage
Linear Charge
to Maintain
Minimum
System
Voltage
V
BATSHORT
50mA Precharge to
Close Pack Protector
Battery FET is ON
Battery
FET
is OFF
I
BATSHORT
Precharge
Phase
Current Regulation
Phase
Voltage Regulation
Phase
Charge Current
Regulation
Threshold
Termination
Current
Threshold
bq24160, bq24160A
bq24161, bq24161B
bq24163, bq24168
SLUSAO0E –NOVEMBER 2011–REVISED NOVEMBER 2013 www.ti.com
Figure 22. Typical bq2416x Charging Profile
PWM Controller in Charge Mode
The bq2416x provides an integrated, fixed-frequency 1.5MHz voltage-mode controller to power the system and
supply the charge current. The voltage loop is internally compensated and provides enough phase margin for
stable operation, allowing the use of small ceramic capacitors with very low ESR.
The input scheme for the bq2416x prevents battery discharge when the supply voltages are lower than VBAT
and also isolates the two inputs from each other. The high-side N-MOSFET (Q1/Q2) switches to control the
power delivered to the output. The DRV LDO provides a supply for the gate drive for the low side MOSFET,
while a bootstrap circuit (BST) with an external bootstrap capacitor is used to boost up the gate drive voltage for
Q1 and Q2.
Both inputs are protected by a cycle-by-cycle current limit that is sensed through the high-side MOSFETs for Q1
and Q2. The threshold for the current limit is set to a nominal 5A peak current. The inputs also utilize an input
current limit that limits the current from the power source.
Battery Charging Process
When the battery is deeply discharged or shorted (V
BAT
< V
BATSHRT
), the bq2416x applies I
BATSHRT
to close the
pack protector switch and bring the battery voltage up to acceptable charging levels. During this time, the battery
FET is linearly regulated and the system output is regulated to V
SYS(REG)
. Once the battery rises above V
BATSHRT
,
the charge current is regulated to the value set in the I
2
C register. The battery FET is linearly regulated to
maintain the system voltage at V
SYS(REG)
. 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 rise, the thermal regulation circuit reduces the
charge current to maintain a die temperature less than 120°C. If the current limit for the SYS output is reached
(limited by the input current limit, or V
IN_DPM
), the SYS output drops to the V
MINSYS
output voltage. When this
happens, the charge current is reduced to provide the system 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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Product Folder Links: bq24160 bq24160A bq24161 bq24161B bq24163 bq24168