bq24160, bq24161
bq24163, bq24168
SLUSAO0A –NOVEMBER 2011–REVISED MARCH 2012
CHARGE MODE OPERATION
Charge Profile
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The internal battery MOSFET is used to charge the battery. When the battery is above the MINSYS votlage, the
the internal FET is on to maximize efficiency and the PWM converter regulates the charge current into the
battery. When battery is less than MINSYS, the SYS is regulated to VSYS(REG) and battery is charged using the
battery FET to regulate the charge current. There are 5 loops that influence the charge current:
•
•
•
•
•
Constant current loop (CC)
Constant voltage loop (CV)
Thermal-regulation loop
Minimum system-voltage loop (MINSYS)
Input-voltage dynamic power-management loop (VIN-DPM)
During the charging process, all five loops are enabled and the one that is dominant takes control. The bq2416x
supports a precision Li-Ion or Li-Polymer charging system for single-cell applications. The Dynamic Power Path
Management (DPPM) feature regulates the system voltage to a minimum of VMINSYS, so that startup is enabled
even for a missing or deeply discharged battery. Figure 22 shows a typical charge profile including the minimum
system output voltage feature.
Voltage Regulation
Phase
Precharge
Phase
Current Regulation
Phase
Regulation
voltage
Charge Current
Regulation
Threshold
System Voltage
V
SYS
V
BATSHORT
Battery
Voltage
Charge Current
Termination
Current
Threshold
I
BATSHORT
Linear Charge
to Maintain
Battery
FET
is OFF
50mA Precharge to
Close Pack Protector
Battery FET is ON
Minimum
System
Voltage
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.
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