User's Manual

LZT 123 1836 42
During microprocessor supervised mode, the GS64 takes a current-limited voltage
source at the CHG_IN pin to implement constant-current charging of a single Li-Ion
cell connected to the VCC pins.
BATTERY
CHARGER
CONTROL
BATTERY
CHARGER
CONTROL
TIMER
TIMER
+
-
3.6V
50mA
3.6V
50mA
MAX CURRENT
DETECTION
ADC
SUI
SUI
TO
uPC
V
REF1
ADIN1
C1
V
REF2
VCC
SINGLE
CELL Li-ION
VOLTAGE
SOURCE
CHG_IN
D1
CHARGE FET
+
-
BATTERY
CHARGER
CONTROL
BATTERY
CHARGER
CONTROL
TIMER
TIMER
+
-
3.6V
50mA
3.6V
50mA
MAX CURRENT
DETECTION
ADC
SUI
SUI
TO
uPC
V
REF1
V
REF1
ADIN1
C1
V
REF2
V
REF2
VCC
SINGLE
CELL Li-ION
VOLTAGE
SOURCE
CHG_IN
D1
CHARGE FET
+
-
Figure 5.8-1 Typical application for pulse charging a battery
5.8.1 Charging Process
Figure 5.8-1 shows a typical battery charging implementation. The voltage source
must be current limited (500 mA max). A reverse current protection diode prevents
external fault conditions from draining the battery. A small (typ 10µF) capacitor
should be placed close to the CHG_IN pin.
In the application shown, a conditioning phase slowly raises the voltage of a deeply
discharged cell to a level suitable for fast-charging. After cell conditioning is
complete, the microprocessor uses the GS64’S ADC converter to monitor the battery
cell’s status and uses the power management block to control the charge-FET.