Datasheet

Operation description L6924U
14/37 Doc ID 14716 Rev 2
6.2 Quasi-pulse mode
The quasi-pulse mode can be used when the system can rely on the current limit of the
upstream adapter to charge the battery. In this case, the fast charge current must be set
higher than the current limit of the adapter. In this mode, the L6924U charges the battery
with the same three phases as in Linear Mode, but the power dissipation is greatly reduced
as shown in Figure 7.
Figure 7. Typical charge curves in quasi pulse mode
The big difference is due to the fact that the charge current is higher than the current limit of
the adapter. During the fast-charge phase, the output voltage of the adapter drops and goes
down to the battery voltage plus the voltage drop across the power MOSFET of the charger,
as shown in the following equation:
Equation 2
Adapter Voltage
Charge Current
Power dissipation
Battery Voltage
End
Charge
Voltage Regulation
Phase
Pre-Charge
Phase
Fast-Charge
Phase
I
LIM
Ilim x Rdson
I
PRETH
I
CHG
V
PRETH
V
OPRGTH
V
ADP
MOSBATADPIN
VVVV
Δ
+
=
=