STw4102 STMicroelectronics, STw4102 Datasheet - Page 18

• Manufacturer Part Number: STw4102
• Description: Dual source USB Li-ion charger with gas gauge
• Manufacturer: STMicroelectronics

Battery charger
6.2
6.3
18/34
Trickle charge
The trickle charge mode is enabled when the battery voltage V
voltage threshold V
above V
constant current method.
The trickle voltage threshold and trickle current are defined by OTP configuration bits and
are factory set to 2.9 V and 60 mA by default. Other values are possible, see
Factory OTP options on page
Charging from a wall adapter
The MAIN input is used for charging from a wall adapter or a dedicated USB charger. The
SEL_DC_USB bit (bit 5 of register REG_CHG0) must be set to 0. The fast charge current is
defined by the external resistor R
The value of the fast charge current is given by the following formula:
In the constant voltage mode, the charger output voltage is regulated with 1% accuracy. The
charger output voltage is programmable using the REG_CHG0 register, bits 3 and 4 (see
Table
Table 11.
Figure 20. Main charge mode
(defined by R
I
trickle
I
charge
11).
REG_CHG0[4]
trickle
(60mA)
I
charge
= 12000 / R
set
0
0
1
1
, the trickle current generator is off and the battery is charged using the
Charger output voltage
I
)
batt
trickle
Trickle
charge
set
. An internal current source charges the battery. When V
Constant current
24.
REG_CHG0[3]
set
connected to the ISET pin, and can be set up to 1 A.
0
1
0
1
Charge current
Fast charge
Battery Voltage
Constant voltage
charge (10% I
Flag end of
batt
4.10V +/-1%
4.20V +/-1%
4.30V +/-1%
4.35V +/-1%
is lower than the trickle
V
charge
Maintenance
charge
charge
)
V
Section 9:
batt
V
V
trickle
charge
batt
STw4102
is
(2.9v)