L6924U STMicroelectronics, L6924U Datasheet - Page 12

• Manufacturer Part Number: L6924U
• Description: Battery Management USB Battery Charger System w/integra
• Manufacturer: STMicroelectronics

Specifications of L6924U

• Product: Charge Management
• Battery Type: Li-Ion
• Output Voltage: 4.2 V
• Output Current: 30 mA
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Package / Case: VFQFPN
• Mounting Style: SMD/SMT
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Operation description
6.1
12/37
Figure 5.
Linear mode
When operating in linear mode, the device works in a way similar to a linear regulator with a
constant current limit protection.
It charges the battery in three phases:
●
●
●
V
of the L6924U. If the battery voltage is lower than the default pre-charge voltage (V
the pre-charge phase takes place. The battery is pre-charged with a low current, internally
set to 10 % of the fast charge current.
When the battery voltage goes higher than V
charge current (I
Finally, when the battery voltage is close to the regulated output voltage (4.2 V), the voltage
regulation phase takes place and the charging current is reduced. The charging process
ends when the charging current reaches the programmed value (I
charging timer expires.
Figure 6
ADP
0.500
0.450
0.400
0.350
0.300
0.250
0.200
0.150
0.100
0.050
0.000
Pre-charging current ("pre-charge" phase).
Constant current ("fast-charge" phase).
Constant voltage ("voltage regulation" phase).
is the output voltage of the upstream AC-DC adapter that is, in turn, the input voltage
0
shows the different phases.
Li-Ion charging profile
USB
200
or I
AC
according to the selection of the MODE pin).
Doc ID 14716 Rev 2
400
Charging time (sec)
600
PRETH
, the battery is charged with the fast
800
ENDTH
1000
) or when the
Ichg
Vbatt
1200
PRETH
L6924U
4.500
4.000
3.500
3.000
2.500
2.000
1.500
1.000
0.500
0.000
),