3. TECHNICAL BRIEF
- 46 -
3.6 Chargind IC (ISL6299, U704)
The ISL6299 is designed for a single-cell Li-ion or Li-polymer battery charging circuit that accepts both
a USB port and a desktop cradle as its power source.
Input Auto Selection
When both input sources are present, the charger selects only one power source to charge the
battery. When the CRDL input is higher than the POR threshold, CRDL is selected as the power
source. Otherwise the USB input is selected. If the CRDL input voltage is below the battery voltage but
the USB input voltage is higher than the battery voltage, then the USB input is used to charge the
battery. The control circuit always breaks both internal power devices before switching from one power
source to the other to avoid a cross conduction of both power MOSFETs.
USB Charge Current
When the USB port is selected as the power source, the charge current enabled by the logic input at
the USBON pin. When the USBON is driven to logic LOW, the charger is disabled. When the USBON
is driven to logic HIGH, the charge current is fixed at a typical value of 380mA. Thus for the USB input,
the USBON pin has a similar function as the EN pin. The following table describes the USB charge
control by both the USBON pin and EN pin The USBON pin is equivalent to a logic LOW when left
floating. Typically the P-channel MOSFET for the USB input has an rDS(ON) of 700mΩ at room
temperature. With a 380mA charge current, the typical head room is 260mV. Thus, if the input voltage
drops to a level that the voltage difference between the USB pin and the BAT pin is less than 260mV,
the rDS(ON) becomes a limiting factor of the charge current; and the charger drops out the constant
current regulation.
(GPIO1)
(ABB AUX2)
(GPIO0)
Charging IC
100K
R729
100K
R730
VUSBIN
10K
R724
C738
1u
VCHARGE
VBAT
D700
CUS02
C740
1u
36K
R728
2V8_VEXT
NA
C731
10K
R731
R722
100K
R723
NA
C739
1u
U704
BAT
10
1
CRDL
GND
8
9
ICDL
IMIN
6
11
PGND
USB
2
7
USBON
_CHG
4
5
_EN
3
_PPR
CHG_STAT
ISL6299
CHG_EN
CUR_MON
Figure 3-15. CIRCUIT FOR BATTERY CHARGING
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Summary of Contents for MG300d
Page 23: ...3 TECHNICAL BRIEF 24 Figure 3 1 SKY74400 FUNCTIONAL BLOCK DIAGRAM Z 3 X B O X C O M ...
Page 83: ...4 TROUBLE SHOOTING 84 4 6 LCD Trouble EMI FILTER CN600 Test Points Z 3 X B O X C O M ...
Page 110: ...5 DOWNLOAD AND CALIBRATION 111 8 Push the START button Z 3 X B O X C O M ...
Page 111: ...5 DOWNLOAD AND CALIBRATION 112 9 Phone test Finish is shown in below screen Z 3 X B O X C O M ...
Page 112: ...6 BLOCK DIAGRAM 113 6 BLOCK DIAGRAM Z 3 X B O X C O M ...
Page 113: ... 114 Z 3 X B O X C O M ...
Page 124: ... 125 MG300d 8 PCB LAYOUT Z 3 X B O X C O M ...
Page 125: ... 126 MG300d 8 PCB LAYOUT Z 3 X B O X C O M ...
Page 137: ... 138 Z 3 X B O X C O M ...
Page 138: ... 139 Z 3 X B O X C O M ...
Page 140: ... 141 12 EXPLODED VIEW REPLACEMENT PART LIST Z 3 X B O X C O M ...
Page 141: ... 142 Z 3 X B O X C O M ...