ISL6292-2CR4Z [INTERSIL]

Li-ion/Li Polymer Battery Charger; 锂离子/锂聚合物电池充电器
ISL6292-2CR4Z
型号: ISL6292-2CR4Z
厂家: Intersil    Intersil
描述:

Li-ion/Li Polymer Battery Charger
锂离子/锂聚合物电池充电器

电池 PC
文件: 总19页 (文件大小:644K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
ISL6292  
®
Data Sheet  
July 25, 2005  
FN9105.6  
Li-ion/Li Polymer Battery Charger  
Features  
The ISL6292 is an integrated single-cell Li-ion or Li- polymer  
battery charger capable of operating with an input voltage as  
low as 2.4V. This charger is designed to work with various  
types of ac adapters or a USB port.  
• Complete Charger for Single-Cell Li-ion Batteries  
• Very Low Thermal Dissipation  
• Integrated Pass Element and Current Sensor  
• No External Blocking Diode Required  
• 1% Voltage Accuracy  
• Programmable Current Limit up to 2A  
• Programmable End-of-Charge Current  
• Charge Current Thermal Foldback  
• NTC Thermistor Interface for Battery Temperature Monitor  
• Accepts Multiple Types of Adapters or USB BUS Power  
• Guaranteed to Operate at 2.65V After Start Up  
• Ambient Temperature Range: -20°C to 70°C  
• Thermally-Enhanced QFN Packages  
• Handheld Devices including Medical Handhelds  
• PDAs, Cell Phones and Smart Phones  
• Portable Instruments, MP3 Players  
The ISL6292 operates as a linear charger when the ac  
adapter is a voltage source. The battery is charged in a  
CC/CV (constant current/constant voltage) profile. The  
charge current is programmable with an external resistor up  
to 2A. The ISL6292 can also work with a current-limited  
adapter to minimize the thermal dissipation, in which case  
the ISL6292 combines the benefits of both a linear charger  
and a pulse charger.  
The ISL6292 features charge current thermal foldback to  
guarantee safe operation when the printed circuit board is  
space limited for thermal dissipation. Additional features  
include preconditioning of an over-discharged battery, an  
NTC thermistor interface for charging the battery in a safe  
temperature range, automatic recharge, and thermally  
enhanced QFN or DFN packages.  
• Self-Charging Battery Packs  
• Stand-Alone Chargers  
• USB Bus-Powered Chargers  
Ordering Information  
PKG.DWG.  
PART # (NOTE) TEMP. RANGE (°C)  
ISL6292-1CR3 -20 to 70  
ISL6292-1CR3-T 10 Ld 3x3 DFN Tape and Reel  
ISL6292-2CR3 -20 to 70 10 Ld 3x3 DFN L10.3x3  
ISL6292-2CR3-T 10 Ld 3x3 DFN Tape and Reel  
ISL6292-1CR4 -20 to 70 16 Ld 4x4 QFN L16.4x4  
ISL6292-1CR4-T 16 Ld 4x4 QFN Tape and Reel  
ISL6292-2CR4 -20 to 70 16 Ld 4x4 QFN L16.4x4  
ISL6292-2CR4-T 16 Ld 4x4 QFN Tape and Reel  
ISL6292-1CR5 -20 to 70 16 Ld 5x5 QFN L16.5x5B  
ISL6292-1CR5-T 16 Ld 5x5 QFN Tape and Reel  
ISL6292-2CR5 -20 to 70 16 Ld 5x5 QFN L16.5x5B  
PACKAGE  
#
• Pb-Free Plus Anneal Available (RoHS Compliant)  
10 Ld 3x3 DFN L10.3x3  
Related Literature  
Technical Brief TB363 “Guidelines for Handling and  
Processing Moisture Sensitive Surface Mount Devices  
(SMDs)”  
Technical Brief TB379 “Thermal Characterization of  
Packaged Semiconductor Devices”  
Technical Brief TB389 “PCB Land Pattern Design and  
Surface Mount Guidelines for QFN Packages”  
Pinouts  
ISL6292 (16 LEAD QFN)  
ISL6292 (10 LEAD DFN)  
TOP VIEW  
TOP VIEW  
ISL6292-2CR5-T 16 Ld 5x5 QFN Tape and Reel  
VIN  
1
10 VBAT  
16 15 14 13  
FAULT  
STATUS  
TIME  
2
3
4
5
9
8
7
6
TEMP  
IREF  
V2P8  
EN  
ISL6292EVAL1 Evaluation Board for the 3x3 DFN Package Part.  
ISL6292EVAL2 Evaluation Board for the 4x4 QFN Package Part.  
VIN  
FAULT  
STATUS  
TIME  
1
2
3
4
12 VBAT  
11 TEMP  
10 IMIN  
NOTE: Intersil Pb-free plus anneal products employ special Pb-free  
material sets; molding compounds/die attach materials and 100% matte  
tin plate termination finish, which are RoHS compliant and compatible  
with both SnPb and Pb-free soldering operations. Intersil Pb-free  
products are MSL classified at Pb-free peak reflow temperatures that  
meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.  
GND  
9
IREF  
5
6
7
8
Add a “Z” to the end of the part # above for lead-free packages, e.g.,  
“ISL6292-1CR3Z-T” is the part # for the lead-free ISL6292-1CR3-T.  
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.  
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.  
Copyright Intersil Americas Inc. 2003-2005. All Rights Reserved  
1
All other trademarks mentioned are the property of their respective owners.  
ISL6292  
Absolute Maximum Ratings  
Thermal Information  
Thermal Resistance (Junction to Ambient)  
5x5 QFN Package (Notes 1, 2) . . . . . .  
4x4 QFN Package (Notes 1, 2) . . . . . .  
3x3 DFN Package (Notes 1, 2) . . . . . .  
Maximum Junction Temperature (Plastic Package) . . . . . . . . 150°C  
Maximum Storage Temperature Range. . . . . . . . . . .-65°C to 150°C  
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C  
Supply Voltage (VIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 7V  
Output Pin Voltage (BAT). . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 5.5V  
Signal Input Voltage (TOEN, TIME, IREF, IMIN) . . . . . . -0.3 to 3.2V  
Output Pin Voltage (STATUS, FAULT). . . . . . . . . . . . . . . . -0.3 to 7V  
Charge Current (For 4x4 or 5x5 QFN Packages) . . . . . . . . . . . 2.1A  
Charge Current (For 3x3 DFN Package) . . . . . . . . . . . . . . . . . 1.6A  
θ
(°C/W)  
θ
(°C/W)  
JC  
JA  
34  
41  
46  
4
4
4
Recommended Operating Conditions  
Ambient Temperature Range. . . . . . . . . . . . . . . . . . . .-20°C to 70°C  
Supply Voltage, VIN. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3V to 6.5V  
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the  
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.  
NOTES:  
1. θ is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See  
JA  
Tech Brief TB379.  
2. θ , “case temperature” location is at the center of the exposed metal pad on the package underside. See Tech Brief TB379.  
JC  
Electrical Specifications Typical values are tested at VIN = 5V and 25°C Ambient Temperature, maximum and minimum values are  
guaranteed over 0°C to 70°C Ambient Temperature with a supply voltage in the range of 4.3V to 6.5V, unless  
otherwise noted.  
PARAMETER  
POWER-ON RESET  
SYMBOL  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
Rising VIN Threshold  
3.0  
3.4  
2.4  
4.0  
V
V
Falling VIN Threshold  
STANDBY CURRENT  
VBAT Pin Sink Current  
VIN Pin Supply Current  
VIN Pin Supply Current  
VOLTAGE REGULATION  
Output Voltage  
2.25  
2.65  
I
VIN floating or EN = LOW  
-
-
-
-
3.0  
µA  
µA  
STANDBY  
I
VBAT floating and EN pulled low  
VBAT floating and EN floating  
30  
1
-
-
VIN  
VIN  
I
mA  
V
V
ISL6292-1  
4.059  
4.10  
4.20  
140  
175  
4.141  
V
V
CH  
CH  
Output Voltage  
ISL6292-2  
4.158  
4.242  
Dropout Voltage  
VBAT = 3.7V, 0.5A, 4X4 or 5X5 package  
VBAT = 3.7V, 0.5A, 3X3 package  
-
-
-
-
mV  
mV  
Dropout Voltage  
CHARGE CURRENT  
Constant Charge Current  
Trickle Charge Current  
Constant Charge Current  
Trickle Charge Current  
Constant Charge Current  
Trickle Charge Current  
End-of-Charge Threshold  
RECHARGE THRESHOLD  
Recharge Voltage Threshold  
Recharge Voltage Threshold  
TRICKLE CHARGE THRESHOLD  
Trickle Charge Threshold Voltage  
I
R
R
= 80k, V  
= 80k, V  
= 3.7V  
= 2.0V  
0.9  
1.0  
110  
450  
45  
1.1  
-
A
CHARGE  
IREF  
IREF  
BAT  
BAT  
I
-
400  
-
mA  
mA  
mA  
mA  
mA  
mA  
TRICKLE  
I
IREF Pin Voltage > 1.2V, V  
IREF Pin Voltage > 1.2V, V  
IREF Pin Voltage < 0.4V, V  
IREF Pin Voltage < 0.4V, V  
= 3.7V  
= 2.0V  
= 3.7V  
= 2.0V  
520  
-
CHARGE  
BAT  
BAT  
BAT  
BAT  
I
TRICKLE  
I
-
-
100  
-
CHARGE  
I
-
10  
TRICKLE  
R
= 80kΩ  
85  
110  
135  
IMIN  
V
V
ISL6292-2  
ISL6292-1  
-
-
4.0  
-
-
V
V
RECHRG  
RECHRG  
3.90  
V
2.7  
2.8  
3.0  
V
MIN  
FN9105.6  
2
July 25, 2005  
ISL6292  
Electrical Specifications Typical values are tested at VIN = 5V and 25°C Ambient Temperature, maximum and minimum values are  
guaranteed over 0°C to 70°C Ambient Temperature with a supply voltage in the range of 4.3V to 6.5V, unless  
otherwise noted. (Continued)  
PARAMETER  
TEMPERATURE MONITORING  
Low Battery Temperature Threshold  
High Battery Temperature Threshold  
Battery Removal Threshold  
Charge Current Foldback Threshold  
Current Foldback Gain  
SYMBOL  
TEST CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
V
V2P8 = 3.0V  
1.40  
0.34  
-
1.50  
0.38  
2.25  
100  
100  
1.60  
0.42  
-
V
V
TMIN  
V
V2P8 = 3.0V  
V2P8 = 3.0V  
TMAX  
V
V
RMV  
T
85  
-
115  
-
°C  
FOLD  
G
mA/°C  
FOLD  
OSCILLATOR  
Oscillation Period  
T
C
= 15nF  
TIME  
2.4  
3.0  
3.6  
ms  
OSC  
LOGIC INPUT AND OUTPUT  
TOEN Input High  
2.0  
-
-
-
-
-
-
-
0.8  
-
V
V
TOEN and EN Input Low  
IREF and IMIN Input High  
IREF and IMIN Input Low  
STATUS/FAULT Sink Current  
1.2  
-
V
0.4  
-
V
Pin Voltage = 0.8V  
5
mA  
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V, T = 25°C,  
IN  
A
R
= R  
IMIN  
= 80k, V  
= 3.7V, Unless Otherwise Noted  
BAT  
IREF  
4.210  
4.208  
4.2015  
4.201  
4.2005  
4.2  
4.206  
4.204  
4.202  
4.200  
4.198  
4.196  
4.194  
4.192  
4.190  
CHARGE CURRENT = 50mA  
R
= 40k  
IREF  
4.1995  
4.199  
4.1985  
4.198  
4.1975  
0
20  
40  
60  
80  
100  
120  
0
0.3  
0.6  
0.9  
1.2  
1.5  
CHARGE CURRENT (A)  
TEMPERATURE (°C)  
FIGURE 1. CHARGER OUTPUT VOLTAGE vs CHARGE  
CURRENT  
FIGURE 2. CHARGER OUTPUT VOLTAGE vs TEMPERATURE  
FN9105.6  
3
July 25, 2005  
ISL6292  
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V, T = 25°C,  
IN  
A
R
= R  
IMIN  
= 80k, V  
= 3.7V, Unless Otherwise Noted (Continued)  
BAT  
IREF  
2
4.3  
4.25  
4.2  
1.8  
2A  
CHARGE CURRENT = 50mA  
1.6  
1.4  
1.5A  
1.2  
1
1A  
0.8  
0.5A  
0.6  
4.15  
4.1  
0.4  
USB500  
USB100  
0.2  
0
4.2  
4.5  
4.8  
5.1  
5.4  
(V)  
5.7  
6
6.3  
3
3.2  
3.4  
3.6  
(V)  
3.8  
4
V
V
BAT  
IN  
FIGURE 3. CHARGER OUTPUT VOLTAGE vs INPUT  
VOLTAGE CHARGE CURRENT IS 50mA  
FIGURE 4. CHARGE CURRENT vs OUTPUT VOLTAGE  
1.6  
2
1.8  
1.6  
1.4  
1.5A  
1.2  
1.4  
1.5A  
1.0  
1.2  
1
2A  
1.0A  
0.8  
0.6  
1A  
0.8  
0.6  
0.4  
0.2  
0
0.5A  
0.5A  
0.4  
0.2  
0.0  
USB500  
USB100  
4.3 4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 6.1 6.3 6.5  
(V)  
0
20  
40  
60  
80  
100  
120  
V
TEMPERATURE (°C)  
IN  
FIGURE 5. CHARGE CURRENT vs AMBIENT TEMPERATURE  
FIGURE 6. CHARGE CURRENT vs INPUT VOLTAGE  
3
2.93  
2.95  
2.928  
2.926  
2.924  
2.922  
2.92  
V2P8 PIN LOADED WITH 2mA  
2.9  
2.85  
2.8  
2.75  
2.7  
3.5  
4
4.5  
5
5.5  
6
6.5  
0
2
4
6
8
10  
V
(V)  
V2P8 LOAD CURRENT (mA)  
IN  
FIGURE 7. V2P8 OUTPUT vs INPUT VOLTAGE  
FIGURE 8. V2P8 OUTPUT vs ITS LOAD CURRENT  
FN9105.6  
4
July 25, 2005  
ISL6292  
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V, T = 25°C,  
IN  
A
R
= R  
IMIN  
= 80k, V  
= 3.7V, Unless Otherwise Noted (Continued)  
BAT  
IREF  
700  
650  
600  
550  
500  
450  
400  
350  
300  
250  
200  
420  
500mA CHARGE CURRENT,  
= 40kΩ  
THERMAL FOLDBACK STARTS  
NEAR 100°C  
400  
380  
360  
340  
320  
300  
R
IREF  
3x3 DFN  
3x3 DFN  
4x4 QFN  
3.6  
4x4 QFN  
80  
280  
260  
3.0  
3.2  
3.4  
3.8  
4.0  
0
20  
40  
60  
100  
120  
V
(V)  
TEMPERATURE (°C)  
BAT  
FIGURE 9. r  
vs TEMPERATURE AT 3.7V OUTPUT  
FIGURE 10. r  
vs OUTPUT VOLTAGE USING CURRENT  
DS(ON)  
DS(ON)  
LIMITED ADAPTERS  
50  
45  
40  
35  
30  
25  
20  
15  
10  
5
1.8  
1.6  
1.4  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
EN = GND  
0
0.0  
0
0
20  
40  
60  
80  
100  
120  
20  
40  
60  
80  
100  
120  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
FIGURE 11. REVERSE CURRENT vs TEMPERATURE  
FIGURE 12. INPUT QUIESCENT CURRENT vs TEMPERATURE  
32  
1.10  
1.05  
1.00  
0.95  
30  
28  
26  
24  
22  
20  
18  
16  
14  
12  
10  
EN = GND  
BOTH VBAT AND EN  
PINS FLOATING  
0.90  
0.85  
0.80  
4.3  
4.6  
4.9  
5.2  
5.5  
(V)  
5.8  
6.1  
6.4  
3.0  
3.5  
4.0  
4.5  
V
5.0  
(V)  
5.5  
6.0  
6.5  
V
IN  
IN  
FIGURE 13. INPUT QUIESCENT CURRENT vs INPUT  
VOLTAGE WHEN SHUTDOWN  
FIGURE 14. INPUT QUIESCENT CURRENT vs INPUT  
VOLTAGE WHEN NOT SHUTDOWN  
FN9105.6  
5
July 25, 2005  
ISL6292  
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V, T = 25°C,  
IN  
A
R
= R  
IMIN  
= 80k, V  
= 3.7V, Unless Otherwise Noted (Continued)  
BAT  
IREF  
28  
24  
20  
16  
12  
8
4
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0  
STATUS PIN VOLTAGE (V)  
FIGURE 15. STATUS/FAULT PIN VOLTAGE vs CURRENT WHEN THE OPEN-DRAIN MOSFET TURNS ON  
FN9105.6  
6
July 25, 2005  
ISL6292  
EN (Pin 7 for 4x4, 5x5; Pin 6 for 3x3)  
EN is the enable logic input. Connect the EN pin to LOW to  
disable the charger or leave it floating to enable the charger.  
Pin Description  
VIN (Pin 1, 15, 16 for 4x4, 5x5; Pin 1 for 3x3)  
VIN is the input power source. Connect to a wall adapter.  
V2P8 (Pin 8 for 4x4, 5x5; Pin 7 for 3x3)  
Fault (Pin 2)  
This is a 2.8V reference voltage output. This pin outputs a  
2.8V voltage source when the input voltage is above POR  
threshold and outputs zero otherwise. The V2P8 pin can be  
used as an indication for adapter presence.  
FAULT is an open-drain output indicating fault status. This  
pin is pulled to LOW under any fault conditions.  
Status (Pin 3)  
STATUS is an open-drain output indicating charging and  
inhibit states. The STATUS pin is pulled LOW when the  
charger is charging a battery.  
IREF (Pin 9 for 4x4, 5x5; Pin 8 for 3x3)  
This is the programming input for the constant charging  
current.  
Time (Pin 4)  
IMIN (Pin 10 for 4x4, 5x5; N/A for 3x3)  
IMIN is the programmable input for the end-of-charge  
current.  
The TIME pin determines the oscillation period by  
connecting a timing capacitor between this pin and GND.  
The oscillator also provides a time reference for the charger.  
TEMP (Pin 11 for 4x4, 5x5; Pin 9 for 3x3)  
TEMP is the input for an external NTC thermistor. The TEMP  
pin is also used for battery removal detection.  
GND (Pin 5)  
GND is the connection to system ground.  
TOEN (Pin 6 for 4x4, 5x5; N/A for 3x3)  
VBAT (Pin 12, 13, 14 for 4x4, 5x5; Pin 10 for 3x3)  
TOEN is the TIMEOUT enable input pin. Pulling this pin to  
LOW disables the TIMEOUT charge-time limit for the fast  
charge modes. Leaving this pin HIGH or floating enables the  
TIMEOUT limit.  
VBAT is the connection to the battery. Typically a 10µF  
Tantalum capacitor is needed for stability when there is no  
battery attached. When a battery is attached, only a 0.1µF  
ceramic capacitor is required.  
Typical Applications  
Typical Application Circuit For 4x4 or 5x5 QFN Package Options  
5V Wall  
Adapter  
VIN  
VBAT  
TOEN  
1µF  
1µF  
V2P8  
1k  
C1  
1kΩ  
C2  
R2  
R1  
Battery  
Pack  
ISL6292  
RU  
T
RT  
D1  
D2  
TEMP  
IREF  
IMIN  
FAULT  
STATUS  
EN  
RIREF  
80kΩ  
R IMIN  
80kΩ  
V2P8  
TIME  
GND  
1µF  
C3  
CTIME  
15nF  
FN9105.6  
7
July 25, 2005  
ISL6292  
Typical Applications (Continued)  
Typical Application Circuit For 3x3 DFN Package Option  
VBA  
T
5V Wall  
Adapter  
VIN  
1µF  
1µF  
C2  
C1  
1k  
1kΩ  
Battery  
Pac  
k
R1  
R2  
ISL6292  
(3X3 DFN)  
T
RT  
D1  
D2  
TEMP  
FAULT  
RU  
STATUS  
V2P8  
IREF  
EN  
1µF  
TIME  
GND  
RIREF C3  
80kΩ  
CTIME  
15nF  
QMAIN  
VIN  
VBAT  
C1  
References  
V2P8  
Temperature  
Monitoring  
QSEN  
100000:1  
Current  
Mirror  
IT  
VIN  
VBAT  
ISEN  
Input_OK  
+
-
VPOR  
+
+
-
IREF  
RIREF  
+
CA  
IR  
100mV  
-
CHRG  
Current  
References  
+
IMIN  
VA  
IMIN  
-
VCH  
RIMIN  
+
-
Trickle/Fast  
MIN_I  
Minbat  
VMIN  
ISEN  
+
-
VRECHRG  
+
-
Recharge  
STATUS  
V2P8  
STATUS  
FAULT  
Under Temp  
Over Temp  
LOGIC  
NTC  
TEMP  
Interface  
Batt Removal  
FAULT  
TOEN  
TIME  
GND  
OSC  
COUNTER  
Input_OK  
EN  
NOTE: For the 3x3 DFN package, the TOEN pin is left floating and the IMIN pin is connected to the V2P8 pin internally.  
FIGURE 16. BLOCK PROGRAM  
FN9105.6  
8
July 25, 2005  
ISL6292  
disabled as needed by the TOEN pin. The trickle mode is  
Theory of Operation  
limited to 1/8 of TIMEOUT and cannot be disabled by the  
The ISL6292 is an integrated charger for single-cell Li-ion or  
Li-polymer batteries. The ISL6292 functions as a traditional  
linear charger when powered with a voltage-source adapter.  
When powered with a current-limited adapter, the charger  
minimizes the thermal dissipation commonly seen in  
traditional linear chargers.  
TOEN pin.  
The charger automatically re-charges the battery when the  
battery voltage drops below a recharge threshold. When the  
wall adapter is not present, the ISL6292 draws less than 1µA  
current from the battery.  
As a linear charger, the ISL6292 charges a battery in the  
popular constant current (CC) and constant voltage (CV)  
Three indication pins are available from the charger to  
indicate the charge status. The V2P8 outputs a 2.8V dc  
voltage when the input voltage is above the power-on reset  
(POR) level and can be used as the power-present  
profile. The constant charge current I  
is programmable  
REF  
up to 2A (1.5A for the 3x3 DFN package) with an external  
resistor or a logic input. The charge voltage V has 1%  
indication. This pin is capable of sourcing a 2mA current, so  
it can also be used to bias external circuits. The STATUS pin  
is an open-drain logic output that turns LOW at the beginning  
of a charge cycle until the end-of-charge (EOC) condition is  
qualified. The EOC condition is: the battery voltage rises  
above the recharge threshold and the charge current falls  
below a user-programmable EOC current threshold. Once  
the EOC condition is qualified, the STATUS output rises to  
HIGH and is latched. The latch is released at the beginning  
of a charge or re-charge cycle. The open-drain FAULT pin  
turns low when any fault conditions occur. The fault  
conditions include the external battery temperature fault, a  
charge time fault, or the battery removal.  
CH  
accuracy over the entire recommended operating condition  
range. The charger always preconditions the battery with  
10% of the programmed current at the beginning of a charge  
cycle, until the battery voltage is verified to be above the  
minimum fast charge voltage, V  
. This low-current  
MIN  
preconditioning charge mode is named trickle mode. The  
verification takes 15 cycles of an internal oscillator whose  
period is programmable with the timing capacitor. A thermal-  
foldback feature removes the thermal concern typically seen  
in linear chargers. The charger reduces the charge current  
automatically as the IC internal temperature rises above  
100°C to prevent further temperature rise. The thermal-  
foldback feature guarantees safe operation when the printed  
circuit board (PCB) is space limited for thermal dissipation.  
Figure 17 shows the typical charge curves in a traditional  
linear charger powered with a constant-voltage adapter.  
From the top to bottom, the curves represent the constant  
input voltage, the battery voltage, the charge current and the  
A TEMP pin monitors the battery temperature to ensure a  
safe charging temperature range. The temperature range is  
programmable with an external negative temperature  
coefficient (NTC) thermistor. The TEMP pin is also used to  
detect the removal of the battery.  
power dissipation in the charger. The power dissipation P  
is given by the following equations:  
CH  
P
= (V -V  
) ⋅ I  
(EQ. 1)  
CH  
IN BAT CHARGE  
The charger offers a safety timer for setting the fast charge  
time (TIMEOUT) limit to prevent charging a dead battery for  
an extensively long time. The TIMEOUT limit can be  
where I  
is the charge current. The maximum power  
dissipation occurs during the beginning of the CC mode. The  
CHARGE  
Trickle  
Mode  
Constant Current  
Mode  
Constant Voltage  
Mode  
Inhibit  
Trickle  
Mode  
Constant Current  
Mode  
Constant Voltage  
Mode  
Inhibit  
Input Voltage  
VIN  
VCH  
VIN  
VCH  
Input Voltage  
Battery Voltage  
Battery Voltage  
VMIN  
VMIN  
IREF  
ILIM  
IREF  
Charge Current  
Charge Current  
IREF/10  
IREF/10  
P1  
P2  
P3  
P1  
P2  
Power Dissipation  
Power Dissipation  
TIMEOUT  
TIMEOUT  
FIGURE 18. TYPICAL CHARGE CURVES USING A CURRENT-  
LIMITED ADAPTER  
FIGURE 17. TYPICAL CHARGE CURVES USING A  
CONSTANT-VOLTAGE ADAPTER  
FN9105.6  
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July 25, 2005  
ISL6292  
maximum power the IC is capable of dissipating is  
dependent on the thermal impedance of the printed-circuit  
board (PCB). Figure 17 shows, with dotted lines, two cases  
that the charge currents are limited by the maximum power  
dissipation capability due to the thermal foldback.  
Applications Information  
Power on Reset (POR)  
The ISL6292 resets itself as the input voltage rises above  
the POR rising threshold. The V2P8 pin outputs a 2.8V  
voltage, the internal oscillator starts to oscillate, the internal  
timer is reset, and the charger begins to charge the battery.  
The two indication pins, STATUS and FAULT, indicate a  
LOW and a HIGH logic signal respectively. Figure 19  
When using a current-limited adapter, the thermal situation  
in the ISL6292 is totally different. Figure 18 shows the typical  
charge curves when a current-limited adapter is employed.  
The operation requires the I  
to be programmed higher  
REF  
of the adapter, as shown in  
illustrates the start up of the charger between t to t .  
0
2
than the limited current I  
LIM  
The ISL6292 has a typical rising POR threshold of 3.4V and  
a falling POR threshold of 2.4V. The 2.4V falling threshold  
guarantees charger operation with a current-limited adapter  
to minimize the thermal dissipation.  
Figure 18. The key difference of the charger operating under  
such conditions occurs during the CC mode.  
The Block Diagram, Figure 16, aids in understanding the  
operation. The current loop consists of the current amplifier  
Charge Cycle  
CA and the sense MOSFET Q  
. The current reference I  
SEN  
R
is programmed by the IREF pin. The current amplifier CA  
regulates the gate of the sense MOSFET Q so that the  
A charge cycle consists of three charge modes: trickle mode,  
constant current (CC) mode, and constant voltage (CV)  
mode. The charge cycle always starts with the trickle mode  
SEN  
matches the reference current I . The  
sensed current I  
SEN  
main MOSFET Q  
R
SEN  
and the sense MOSFET Q  
form a  
until the battery voltage stays above V  
(2.8V typical) for  
MAIN  
MIN  
15 consecutive cycles of the internal oscillator. If the battery  
voltage drops below V during the 15 cycles, the 15-cycle  
current mirror with a ratio of 100,000:1, that is, the output  
charge current is 100,000 times I . In the CC mode, the  
R
MIN  
current loop tries to increase the charge current by  
counter is reset and the charger stays in the trickle mode.  
The charger moves to the CC mode after verifying the  
battery voltage. As the battery-pack terminal voltage rises to  
enhancing the sense MOSFET Q  
, so that the sensed  
SEN  
current matches the reference current. On the other hand,  
the adapter current is limited, the actual output current will  
never meet what is required by the current reference. As a  
result, the current error amplifier CA keeps enhancing the  
the final charge voltage V , the CV mode begins. The  
CH  
terminal voltage is regulated at the constant V  
in the CV  
CH  
mode and the charge current is expected to decline. After  
the charge current drops below I (programmable for the  
Q
as well as the main MOSFET Q , until they are  
SEN  
MAIN  
MIN  
4x4 and 5X5 package and programmed to 1/10 of I  
fully turned on. Therefore, the main MOSFET becomes a  
power switch instead of a linear regulation device. The  
power dissipation in the CC mode becomes:  
for  
REF  
the 3x3 package, see End-of-Charge Current for more  
detail), the ISL6292 indicates the end-of-charge (EOC) with  
the STATUS pin. The charging actually does not terminate  
until the internal timer completes its length of TIMEOUT in  
order to bring the battery to its full capacity. Signals in a  
2
P
= R  
I  
CH  
DS(ON) CHARGE  
(EQ. 2)  
where r  
is the resistance when the main MOSFET is  
DS(ON)  
charge cycle are illustrated in Figure 19 between points t to  
2
fully turned on. This power is typically much less than the  
peak power in the traditional linear mode.  
t .  
5
The worst power dissipation when using a current-limited  
adapter typically occurs at the beginning of the CV mode, as  
shown in Figure 18. The equation EQ. 1 applies during the  
CV mode. When using a very small PCB whose thermal  
impedance is relatively large, it is possible that the internal  
temperature can still reach the thermal foldback threshold. In  
that case, the IC is thermally protected by lowering the  
charge current, as shown with the dotted lines in the charge  
current and power curves. Appropriate design of the adapter  
can further reduce the peak power dissipation of the  
ISL6292. See the Application Information section for more  
information.  
VIN  
POR Threshold  
Charge Cycle  
V2P8  
Charge Cycle  
STATUS  
FAULT  
VBAT  
15 Cycles to  
1/8 TIMEOUT  
VRECHRG  
2.8V VMIN  
15 Cycles  
Figure 19 illustrates the typical signal waveforms for the  
linear charger from the power-up to a recharge cycle. More  
detailed Applications Information is given below.  
IMIN  
ICHARGE  
t8  
t0 t1 t2 t3  
t4  
t5  
t6 t7  
FIGURE 19. OPERATION WAVEFORMS  
FN9105.6  
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July 25, 2005  
ISL6292  
The following events initiate a new charge cycle:  
• POR,  
Disabling TIMEOUT Limit  
The TIMEOUT limit for the fast charge modes can be  
disabled by pulling the TOEN pin to LOW or shorting it to  
GND. When this happens, the charger becomes a current-  
limited LDO (low-dropout) supply with its voltage regulated at  
• a new battery being inserted (detected by TEMP pin),  
• the battery voltage drops below a recharge threshold after  
completing a charge cycle,  
the final charge voltage V  
and the current limit determined  
CH  
by the IREF pin. If the LDO load current drops below the  
end-of-charge current (refer to End-of-Charge section), the  
STATUS pin will indicate.  
• recovery from an battery over-temperature fault,  
• or, the EN pin is toggled from GND to floating.  
Further description of these events are given later in this  
data sheet.  
The trickle charge time limit, however, is not disabled even  
when the TOEN pin is pulled to LOW. The charger operates  
in the trickle mode at the beginning of a charge cycle even if  
the TIMEOUT is disabled. Leaving the TOEN pin floating is  
recommended to enable the TIMEOUT. Driving the TOEN  
pin above 3.0V is not recommended.  
Recharge  
After a charge cycle completes, charging is prohibited until  
the battery voltage drops to a recharge threshold, V  
RECHRG  
(see Electrical Specifications). Then a new charge cycle  
starts at point t and ends at point t , as shown in Figure 19.  
Charge Current Programming  
The charge current is programmed by the IREF pin. There  
are three ways to program the charge current:  
6
8
The safety timer is reset at t .  
6
Internal Oscillator  
The internal oscillator establishes a timing reference. The  
oscillation period is programmable with an external timing  
1. driving the IREF pin above 1.3V  
2. driving the IREF pin below 0.4V,  
capacitor, C  
, as shown in Typical Applications. The  
TIME  
3. or using the R  
as shown in the Typical Applications.  
IREF  
oscillator charges the timing capacitor to 1.5V and then  
The voltage of IREF is regulated to a 0.8V reference voltage  
when not driven by any external source. The charging  
current during the constant current mode is 100,000 times  
discharges it to 0.5V in one period, both with 10µA current.  
The period T  
is:  
OSC  
that of the current in the R  
resistor. Hence, depending  
on how IREF pin is used, the charge current is,  
6
IREF  
T
= 0.2 10 C  
(seconds)  
(EQ. 3)  
OSC  
TIME  
A 1nF capacitor results in a 0.2ms oscillation period. The  
accuracy of the period is mainly dependent on the accuracy  
of the capacitance and the internal current source.  
V
R
V
> 1.3V  
IREF  
IREF  
IREF  
500mA  
0.8V  
IREF  
5
-----------------  
I
=
× 10 (A)  
(EQ. 5)  
REF  
R
100mA  
Total Charge Time  
< 0.4V  
The total charge time for the CC mode and CV mode is  
limited to a length of TIMEOUT. A 22-stage binary counter  
increments each oscillation period of the internal oscillator to  
set the TIMEOUT. The TIMEOUT can be calculated as:  
The 500mA current is a guaranteed maximum value for  
high-power USB port, with the typical value of 450mA. The  
100mA current is also a guaranteed maximum value for the  
low-power USB port. This design accommodates the USB  
power specification.  
The internal reference voltage at the IREF pin is capable of  
sourcing less than 100µA current. When pulling down the  
IREF pin with a logic circuit, the logic circuit needs to be able  
to sink at least 100µA current.  
C
1nF  
22  
TIME  
-----------------  
TIMEOUT = 2 T  
= 14 ⋅  
(minutes)  
(EQ. 4)  
OSC  
A 1nF capacitor leads to 14 minutes of TIMEOUT. For  
example, a 15nF capacitor sets the TIMEOUT to be 3.5  
hours. The charger has to reach the end-of-charge condition  
before the TIMEOUT, otherwise, a TIMEOUT fault is issued.  
The TIMEOUT fault latches up the charger. There are two  
ways to release such a latch-up: either to recycle the input  
power, or toggle the EN pin to disable the charger and then  
enable it again.  
When the adapter is current limited, it is recommended that  
the reference current be programmed to at least 30% higher  
than the adapter current limit (which equals the charge  
current). In addition, the charge current should be at least  
350mA so that the voltage difference between the VIN and  
the VBAT pins is higher than 100mV. The 100mV is the  
offset voltage of the input-output voltage comparator shown  
in the block diagram.  
The trickle mode charge has a time limit of 1/8 TIMEOUT. If  
the battery voltage does not reach V  
within this limit, a  
MIN  
TIMEOUT fault is issued and the charger latches up. The  
charger stays in trickle mode for at least 15 cycles of the  
internal oscillator and, at most, 1/8 of TIMEOUT, as shown in  
Figure 19.  
FN9105.6  
11  
July 25, 2005  
ISL6292  
charge unless the battery voltage is already above the  
End-of-Charge (EOC) Current  
The end-of-charge current I sets the level at which the  
charger starts to indicate the end of the charge with the  
STATUS pin, as shown in Figure 19. The charger actually  
does not terminate charging until the end of the TIMEOUT,  
recharge threshold.  
MIN  
2.8V Bias Voltage  
The ISL6292 provides a 2.8V voltage for biasing the internal  
control and logic circuit. This voltage is also available for  
external circuits such as the NTC thermistor circuit. The  
maximum allowed external load is 2mA.  
as described in the Total Charge Time section. The I  
set in two ways, by connecting a resistor between the IMIN  
pin and ground, or by connecting the IMIN pin to the V2P8  
is  
MIN  
pin. When programming with the resistor, the I  
the equation below.  
is set in  
NTC Thermistor  
The ISL6292 uses two comparators (CP2 and CP3) to form a  
window comparator, as shown in Figure 22. When the TEMP  
MIN  
V
4
0.8V  
REF  
×10  
(A)  
(EQ. 6)  
---------------- ----------------  
I
= 10000 ⋅  
=
MIN  
pin voltage is “out of the window,” determined by the V  
R
R
IMIN  
TMIN  
IMIN  
and V  
, the ISL6292 stops charging and indicates a fault  
TMAX  
condition. When the temperature returns to the set range, the  
charger re-starts a charge cycle. The two MOSFETs, Q1 and  
Q2, produce hysteresis for both upper and lower thresholds.  
The temperature window is shown in Figure 21.  
where R  
IMIN  
is the resistor connected between the IMIN pin  
and the ground. When connected to the V2P8 pin, the I  
MIN  
is set to 1/10 of I  
GND. Under this exception, I  
the 3X3 DFN package, the IMIN pin is bonded internally to  
V2P8.  
, except when the IREF pin is shorted to  
REF  
is 5mA. For the ISL6292 in  
MIN  
2.8V  
Charge Current Thermal Foldback  
Over-heating is always a concern in a linear charger. The  
maximum power dissipation usually occurs at the beginning  
of a charge cycle when the battery voltage is at its minimum  
but the charge current is at its maximum. The charge current  
thermal foldback function in the ISL6292 frees users from  
the over-heating concern.  
VTMIN (1.4V)  
VTMIN- (1.2V)  
TEMP  
Pin  
Voltage  
VTMAX+ (0.406V)  
VTMAX (0.35V)  
Figure 20 shows the current signals at the summing node of  
the current error amplifier CA in the Block Diagram. I is the  
0V  
R
reference. I is the current from the Temperature Monitoring  
T
Under  
Temp  
block. The I has no impact on the charge current until the  
T
internal temperature reaches approximately 100°C; then I  
T
Over  
Temp  
rises at a rate of 1µA/°C. When I rises, the current control  
T
loop forces the sensed current I  
SEN  
to reduce at the same  
FIGURE 21. CRITICAL VOLTAGE LEVELS FOR TEMP PIN  
rate. As a mirrored current, the charge current is 100,000  
times that of the sensed current and reduces at a rate of  
100mA/°C. For a charger with the constant charge current  
set at 1A, the charge current is reduced to zero when the  
internal temperature rises to 110°C. The actual charge  
current settles between 100°C to 110°C.  
2.8V  
V2P8  
ISL6292  
R1  
40K  
V
Battery  
Removal  
RMV  
CP1  
-
IR  
R2  
+
R
U
60K  
V
Under  
Temp  
TMIN  
CP2  
-
R3  
IT  
+
75K  
To TEMP Pin  
TEMP  
Q1  
ISEN  
Over  
Temp  
CP3  
R4  
R
T
-
25K  
V
TMAX  
+
100OC  
Temperature  
Q2  
R5  
4K  
GND  
FIGURE 20. CURRENT SIGNALS AT THE AMPLIFIER CA INPUT  
Usually the charge current should not drop below I  
because of the thermal foldback. For some extreme cases if  
that does happen, the charger does not indicate end-of-  
MIN  
FIGURE 22. THE INTERNAL AND EXTERNAL CIRCUIT FOR  
THE NTC INTERFACE  
FN9105.6  
July 25, 2005  
12  
ISL6292  
As the TEMP pin voltage rises from low and exceeds the  
The temperature hysteresis can be estimated. At the low  
temperature, the hysteresis is approximately,  
1.4V threshold, the under temperature signal rises and does  
not clear until the TEMP pin voltage falls below the 1.2V  
falling threshold. Similarly, the over-temperature signal is  
given when the TEMP pin voltage falls below the 0.35V  
threshold and does not clear until the voltage rises above  
0.406V. The actual accuracy of the 2.8V is not important  
because all the thresholds and the TEMP pin voltage are  
ratios determined by the resistor dividers, as shown in  
Figure 22.  
1.4V-1.2V  
o
-------------------------------  
(EQ. 11)  
T
3  
( C)  
hysLOW  
1.4V 0.051  
where 0.051 is the NTC at 3°C. Similarly, the high  
temperature hysteresis is,  
0.406V-0.35V  
o
-------------------------------------  
T
4  
( C)  
hysHIGH  
0.35V 0.039  
(EQ. 12)  
where the 0.039 is the NTC at 47°C.  
The NTC thermistor is required to have a resistance ratio of  
7:1 at the low and the high temperature limits, that is,  
For applications that do not need to monitor the battery  
temperature, the NTC thermistor can be replaced with a  
R
R
COLD  
(EQ. 7)  
-------------------  
= 7  
regular resistor of a half value of the pull up resistor R .  
U
HOT  
Another option is to connect the TEMP pin to the IREF pin  
that has a 0.8V output. With such connection, the IREF pin  
can no longer be programmed with logic inputs.  
This is because at the low temperature limit, the TEMP pin  
voltage is 1.4V, which is 1/2 of the 2.8V bias. Thus,  
Battery Removal Detection  
R
= R  
U
(EQ. 8)  
COLD  
The ISL6292 assumes that the thermistor is co-packed with  
the battery and is removed together with the battery. When  
the charger senses a TEMP pin voltage that is 2.1V or  
higher, it assumes that the battery is removed. The battery  
removal detection circuit is also shown in Figure 22. When a  
battery is removed, a FAULT signal is indicated and charging  
is halted. When a battery is inserted again, a new charge  
cycle starts.  
where R is the pull-up resistor as shown in Figure 22. On  
U
the other hand, at the high temperature limit the TEMP pin  
voltage is 0.35V, 1/8 of the 2.8V bias. Therefore,  
R
7
U
(EQ. 9)  
-------  
R
=
HOT  
Various NTC thermistors are available for this application.  
Table 1 shows the resistance ratio and the negative  
temperature coefficient of the curve-1 NTC thermistor from  
Vishay (http://www.vishay.com) at various temperatures. The  
resistance at 3°C is approximately seven times the  
resistance at 47°C, that is:  
Indications  
The ISL6292 has three indications: the input presence, the  
charge status, and the fault indication. The input presence is  
indicated by the V2P8 pin while the other two indications are  
presented by the STATUS pin and FAULT pin respectively.  
Figure 23 shows the V2P8 pin voltage vs. the input voltage.  
Table 2 summarizes the other two pins.  
R
o
3 C  
-----------------  
= 7  
(EQ. 10)  
R
o
47 C  
Therefore, if 3°C is the low temperature limit, then the high  
temperature limit is approximately 47°C. The pull-up resistor  
U
3.4V  
R
can choose the same value as the resistance at 3°C.  
2.4V  
TABLE 1. RESISTANCE RATIO OF VISHAY’S CURVE-1 NTC  
TEMPERATURE (°C)  
R /R  
25°C  
NTC (%/°C)  
T
2.8V  
VIN  
0
3
3.266  
5.1  
5.1  
5.0  
4.4  
4.0  
3.9  
3.9  
2.806  
2.540  
5
V2P8  
25  
45  
47  
50  
1.000  
0.4368  
0.4041  
0.3602  
FIGURE 23. THE V2P8 PIN OUTPUT vs THE INPUT VOLTAGE  
AT THE VIN PIN. VERTICAL: 1V/DIV,  
HORIZONTAL: 100ms/DIV.  
FN9105.6  
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July 25, 2005  
ISL6292  
current-voltage characteristics curve, such as point A, to  
higher voltage until reaching the breaking point B, as shown  
in Figure 24.  
Shutdown  
The ISL6292 can be shutdown by pulling the EN pin to  
ground. When shut down, the charger draws typically less  
than 30µA current from the input power and the 2.8V output  
at the V2P8 pin is also turned off. The EN pin needs be  
driven with an open-drain or open-collector logic output, so  
that the EN pin is floating when the charger is enabled.  
The adapter is equivalent to a voltage source with output  
resistance when running in the constant-voltage region;  
because of this characteristic. As the charge current drops,  
the adapter output moves from point B to point C, shown in  
Figure 24.  
TABLE 2. STATUS INDICATIONS  
The battery pack can be approximated as an ideal cell with a  
lumped-sum resistance in series, also shown in Figure 24.  
The ISL6292 charger sits between the adapter and the  
battery.  
FAULT STATUS  
INDICATION  
High  
High  
Charge completed with no fault (Inhibit) or  
Standby  
High  
Low  
Low  
Charging in one of the three modes  
Fault  
C
High  
VNL  
VFL  
rO =(VNL - VFL)/ILIM  
*Both outputs are pulled up with external resistors.  
B
VPACK  
RPACK  
Input and Output Capacitor Selection  
rO  
Typically any type of capacitors can be used for the input  
and the output. Use of a 0.47µF or higher value ceramic  
capacitor for the input is recommended. When the battery is  
attached to the charger, the output capacitor can be any  
ceramic type with the value higher than 0.1µF. However, if  
there is a chance the charger will be used as an LDO linear  
regulator, a 10µF tantalum capacitor is recommended.  
ILIM  
VNL  
VCELL  
A
ILIM  
FIGURE 24. THE IDEAL I-V CHARACTERISTICS OF A  
CURRENT LIMITED ADAPTER  
Current-Limited Adapter  
Figure 24 shows the ideal current-voltage characteristics of  
Working with Current-Limited Adapter  
a current-limited adapter. V is the no-load adapter output  
NL  
voltage and V is the full load voltage at the current limit  
FL  
As described earlier, the ISL6292 minimizes the thermal  
dissipation when running off a current-limited ac adapter, as  
shown in Figure 18. The thermal dissipation can be further  
reduced when the adapter is properly designed. The  
following demonstrates that the thermal dissipation can be  
minimized if the adapter output reaches the full-load output  
voltage (point B in Figure 24) before the battery pack voltage  
reaches the final charge voltage (4.1V or 4.2V). The  
assumptions for the following discussion are: the adapter  
current limit = 750mA, the battery pack equivalent  
resistance = 200m, and the charger ON resistance is  
350m.  
I
. Before its output current reaches the limit I  
, the  
LIM  
LIM  
adapter presents the characteristics of a voltage source. The  
slope r represents the output resistance of the voltage  
O
supply. For a well regulated supply, the output resistance  
can be very small, but some adapters naturally have a  
certain amount of output resistance.  
The adapter is equivalent to a current source when running  
in the constant-current region. Being a current source, its  
output voltage is dependent on the load, which, in this case,  
is the charger and the battery. As the battery is being  
charged, the adapter output rises from a lower voltage in the  
Adapter  
Adapter  
rO  
Adapter  
rO  
Charger  
RDS(ON)  
Charger  
RDS(ON)  
Charger  
VADAPTER  
VPACK  
VADAPTER  
VPACK  
VADAPTER  
VPACK  
4.2V DC  
Output  
ILIM  
VNL  
VNL  
I
I
I
RPACK  
RPACK  
RPACK  
Battery  
Pack  
VCELL  
VCELL  
Battery  
Pack  
VCELL  
Battery  
Pack  
(B) THE EQUIVALENT CIRCUIT IN THE  
RESISTANCE-LIMIT REGION  
(C) THE EQUIVALENT CIRCUIT WHEN THE  
PACK VOLTAGE REACHES THE FINAL  
CHARGE VOLTAGE  
(A) THE EQUIVALENT CIRCUIT IN THE  
CONSTANT CURRENT REGION  
FIGURE 25. THE EQUIVALENT CIRCUIT OF THE CHARGING SYSTEM WORKING WITH CURRENT LIMITED ADAPTERS  
FN9105.6  
July 25, 2005  
14  
ISL6292  
When charging in the constant-current region, the pass  
element in the charger is fully turned on. The charger is  
equivalent to the on-resistance of the internal P-channel  
MOSFET. The entire charging system is equivalent to the  
circuit shown in Figure 25 (A). The charge current is the  
is shown in Figure 25(B). Eventually, the battery pack voltage  
will reach 4.2V (or 4.1V) because the adapter no-load voltage is  
higher than 4.2V (or 4.1V), then Figure 25(C) becomes the  
equivalent circuit until charging ends. In this case, the worst-  
case thermal dissipation also occurs in the constant-current  
charge mode. Figure 26 (B) shows the I-V curves of the  
adapter output, the battery pack voltage and the cell voltage for  
constant current limit I  
, and the adapter output voltage  
LIM  
can be easily found out as,  
the case V = 4V. In the case, the full-load voltage is lower  
FL  
V
= I  
R  
+ V  
DS(ON) PACK  
(EQ. 13)  
Adapter  
LIM  
than the final charge voltage (4.2V), but the charger is still able  
to fully charge the battery as long as the no-load voltage is  
above 4.2V. Figure 27 (B) illustrates the adapter voltage,  
battery pack voltage, the charge current and the power  
dissipation in the charger respectively in the time domain.  
where V  
is the battery pack voltage. The power  
PACK  
dissipation in the charger is given in EQ. 2, where I  
CHARGE  
= I  
.
LIM  
Based on the above discussion, the worst-case power  
dissipation occurs during the constant-current charge mode  
if the adapter full-load voltage is lower than the critical  
voltage given in EQ. 14. Even if that is not true, the power  
dissipation is still much less than the power dissipation in the  
traditional linear charger. Figure 28 and 29 are scope-  
captured waveforms to demonstrate the operation with a  
current-limited adapter.  
A critical condition of the adapter design is that the adapter  
output reaches point B in Figure 24 at the same time as the  
battery pack voltage reaches the final charge voltage (4.1V  
or 4.2V), that is:  
V
= I  
R  
+ V  
DS(ON) CH  
(EQ. 14)  
Critical  
LIM  
For example, if the final charge voltage is 4.2V, the r  
is 350m, and the current limit I  
DS(ON)  
The waveforms in Figure 28 are the adapter output voltage  
(1V/div), the battery voltage (1V/div), and the charge current  
(200mA/div) respectively. The time scale is 1ks/div. The  
adapter current is limited to 600mA and the charge current is  
programmed to 1A. Note that the voltage difference is only  
approximately 200mV and the adapter voltage tracks the  
battery voltage in the CC mode. Figure 28 also shows the  
resistance-limit mode before entering the CV mode.  
is 750mA, the critical  
LIM  
adapter full-load voltage is 4.4625V.  
When the above condition is true, the charger enters the  
constant-voltage mode simultaneously as the adapter exits  
the current-limit mode. The equivalent charging system is  
shown in Figure 25 (C). Since the charge current drops at a  
higher rate in the constant-voltage mode than the increase  
rate of the adapter voltage, the power dissipation decreases  
as the charge current decreases. Therefore, the worst case  
thermal dissipation occurs in the constant-current charge  
mode. Figure 26 (A) shows the I-V curves of the adapter  
output, the battery pack voltage and the cell voltage during  
the charge. The 5.9V no-load voltage is just an example  
value higher than the full-load voltage. The cell voltage  
4.05V uses the assumption that the pack resistance is  
200m. Figure 27 (A) illustrates the adapter voltage, battery  
pack voltage, the charge current and the power dissipation in  
the charger respectively in the time domain.  
5.9V  
4.2V  
VADAPTER  
4.4625V  
4.2V  
VPACK  
VCELL  
(A)  
(B)  
4.05V  
0.75A  
VPACK  
If the battery pack voltage reaches 4.2V (or 4.1V) before the  
adapter reaches point B in Figure 24, a voltage step is  
expected at the adapter output when the pack voltage  
reaches the final charge voltage. As a result, the charger  
power dissipation is also expected to have a step rise. This  
case is shown in Figure 18 as well as Figure 27 (C). Under  
this condition, the worst case thermal dissipation in the  
charger happens when the charger enters the constant  
voltage mode.  
VNL  
VADAPTER  
4.2V  
4.2V  
4.0V  
3.775V  
VCELL  
3.625V  
0.55A  
0.75A  
If the adapter voltage reaches the full-load voltage before the  
pack voltage reaches 4.2V (or 4.1V), the charger will  
experience the resistance-limit situation. In this situation, the  
ON resistance of the charger is in series with the adapter output  
resistance. The equivalent circuit for the resistance-limit region  
FIGURE 26. THE I-V CHARACTERISTICS OF THE CHARGER  
WITH DIFFERENT CURRENT LIMITED  
ADAPTERS  
FN9105.6  
15  
July 25, 2005  
ISL6292  
VIN  
VIN  
VIN  
VPACK  
VPACK  
VPACK  
Charge  
Current  
Charge  
Current  
Charge  
Current  
Power  
Power  
Power  
TIME  
TIME  
TIME  
Res  
Const. Cur  
Constant Voltage  
Const. Cur  
Const. Cur  
Constant Voltage  
Constant Voltage  
Limit  
(C)  
(A)  
(B)  
FIGURE 27. THE OPERATING CURVES WITH THREE DIFFERENT CURRENT LIMITED ADAPTERS  
Figure 29 shows the actual captured waveforms depicted in  
Figure 27 (C). The constant charge current is 750mA. A step  
in the adapter voltage during the transition from CC mode to  
CV mode is demonstrated.  
IREF Programming Using Current-Limited Adapter  
The ISL6292 has 10% tolerance for the charge current.  
Typically the current-limited adapter also has 10% tolerance.  
In order to guarantee proper operation, it is recommended  
that the nominal charge current be programmed at least  
30% higher than the nominal current limit of the adapter.  
CV Mode  
Board Layout Recommendations  
CC Mode  
The ISL6292 internal thermal foldback function limits the  
charge current when the internal temperature reaches  
approximately 100°C. In order to maximize the current  
capability, it is very important that the exposed pad under the  
package is properly soldered to the board and is connected  
to other layers through thermal vias. More thermal vias and  
more copper attached to the exposed pad usually result in  
better thermal performance. On the other hand, the number  
of vias is limited by the size of the pad. The exposed pads for  
the 5x5 and 4x4 QFN packages are able to have 9 and 5  
vias respectively. The 3x3 DFN package allows 8 vias be  
placed in two rows. Since the pins on the 3x3 DFN package  
are on only two sides, as much top layer copper as possible  
should be connected to the exposed pad to minimize the  
thermal impedance. Refer to the ISL6292 evaluation boards  
for layout examples.  
Resistance Limit Mode  
FIGURE 28. SCOPE CAPTURED WAVEFORMS SHOWING THE  
THREE MODES  
1 hour  
FIGURE 29. SCOPE CAPTURED WAVEFORMS SHOWING THE  
CASE THAT THE FULL-LOAD ADAPTER  
VOLTAGE IS HIGHER THAN THE CRITICAL  
VOLTAGE  
FN9105.6  
16  
July 25, 2005  
ISL6292  
Dual Flat No-Lead Plastic Package (DFN)  
2X  
L10.3x3  
0.15  
C A  
2X  
10 LEAD DUAL FLAT NO-LEAD PLASTIC PACKAGE  
D
A
MILLIMETERS  
0.15 C  
B
SYMBOL  
MIN  
0.80  
NOMINAL  
0.90  
MAX  
1.00  
NOTES  
A
A1  
A3  
b
-
-
0.18  
1.95  
1.55  
-
0.05  
-
E
0.20 REF  
0.23  
-
6
0.28  
2.05  
1.65  
5,8  
INDEX  
AREA  
D
3.00 BSC  
2.00  
-
D2  
E
7,8  
TOP VIEW  
SIDE VIEW  
B
A
3.00 BSC  
1.60  
-
E2  
e
7,8  
0.10 C  
0.08 C  
0.50 BSC  
-
-
k
0.25  
0.30  
-
-
L
0.35  
0.40  
8
C
A3  
SEATING  
PLANE  
N
10  
2
Nd  
5
3
7
8
Rev. 3 6/04  
D2  
NOTES:  
(DATUM B)  
1. Dimensioning and tolerancing conform to ASME Y14.5-1994.  
2. N is the number of terminals.  
3. Nd refers to the number of terminals on D.  
D2/2  
1
2
6
INDEX  
AREA  
k
NX  
E2  
4. All dimensions are in millimeters. Angles are in degrees.  
(DATUM A)  
5. Dimension b applies to the metallized terminal and is measured  
between 0.15mm and 0.30mm from the terminal tip.  
E2/2  
6. The configuration of the pin #1 identifier is optional, but must be  
located within the zone indicated. The pin #1 identifier may be  
either a mold or mark feature.  
NX L  
8
N
N-1  
e
7. Dimensions D2 and E2 are for the exposed pads which provide  
NX b  
improved electrical and thermal performance.  
5
8. Nominal dimensions are provided to assist with PCB Land  
Pattern Design efforts, see Intersil Technical Brief TB389.  
(Nd-1)Xe  
0.10 M C A B  
REF.  
BOTTOM VIEW  
C
L
0.415  
NX (b)  
(A1)  
L
0.200  
NX b  
NX L  
5
e
SECTION "C-C"  
TERMINAL TIP  
C C  
C
FOR ODD TERMINAL/SIDE  
FN9105.6  
17  
July 25, 2005  
ISL6292  
Quad Flat No-Lead Plas tic Package (QFN)  
Micro Lead Frame Plas tic Package (MLFP)  
L16.4x4  
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE  
(COMPLIANT TO JEDEC MO-220-VGGC ISSUE C)  
MILLIMETERS  
SYMBOL  
MIN  
0.80  
NOMINAL  
MAX  
1.00  
0.05  
1.00  
NOTES  
A
A1  
A2  
A3  
b
0.90  
-
-
-
-
-
-
9
0.20 REF  
9
0.23  
1.95  
1.95  
0.28  
0.35  
2.25  
2.25  
5, 8  
D
4.00 BSC  
-
D1  
D2  
E
3.75 BSC  
9
2.10  
7, 8  
4.00 BSC  
-
E1  
E2  
e
3.75 BSC  
9
2.10  
7, 8  
0.65 BSC  
-
k
0.25  
0.50  
-
-
-
-
L
0.60  
0.75  
0.15  
8
L1  
N
-
16  
4
4
-
10  
2
Nd  
Ne  
P
3
3
-
-
0.60  
12  
9
θ
-
9
Rev. 5 5/04  
NOTES:  
1. Dimensioning and tolerancing conform to ASME Y14.5-1994.  
2. N is the number of terminals.  
3. Nd and Ne refer to the number of terminals on each D and E.  
4. All dimensions are in millimeters. Angles are in degrees.  
5. Dimension b applies to the metallized terminal and is measured  
between 0.15mm and 0.30mm from the terminal tip.  
6. The configuration of the pin #1 identifier is optional, but must be  
located within the zone indicated. The pin #1 identifier may be  
either a mold or mark feature.  
7. Dimensions D2 and E2 are for the exposed pads which provide  
improved electrical and thermal performance.  
8. Nominal dimensionsare provided toassistwith PCBLandPattern  
Design efforts, see Intersil Technical Brief TB389.  
9. Features and dimensions A2, A3, D1, E1, P & θ are present when  
Anvil singulation method is used and not present for saw  
singulation.  
10. Depending on the method of lead termination at the edge of the  
package, a maximum 0.15mm pull back (L1) maybe present. L  
minus L1 to be equal to or greater than 0.3mm.  
FN9105.6  
18  
July 25, 2005  
ISL6292  
Quad Flat No-Lead Plas tic Package (QFN)  
Micro Lead Frame Plas tic Package (MLFP)  
L16.5x5B  
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE  
(COMPLIANT TO JEDEC MO-220VHHB ISSUE C)  
MILLIMETERS  
SYMBOL  
A
MIN  
0.80  
NOMINAL  
MAX  
1.00  
0.05  
1.00  
NOTES  
0.90  
-
A1  
A2  
A3  
b
-
-
-
-
-
9
0.20 REF  
9
0.28  
2.95  
2.95  
0.33  
0.40  
3.25  
3.25  
5, 8  
D
5.00 BSC  
-
D1  
D2  
E
4.75 BSC  
9
3.10  
7, 8  
5.00 BSC  
-
E1  
E2  
e
4.75 BSC  
9
3.10  
7, 8  
0.80 BSC  
-
k
0.25  
0.35  
-
-
-
-
L
0.60  
0.75  
0.15  
8
L1  
N
-
16  
4
4
-
10  
2
Nd  
Ne  
P
3
3
-
-
0.60  
12  
9
θ
-
9
Rev. 1 10/02  
NOTES:  
1. Dimensioning and tolerancing conform to ASME Y14.5-1994.  
2. N is the number of terminals.  
3. Nd and Ne refer to the number of terminals on each D and E.  
4. All dimensions are in millimeters. Angles are in degrees.  
5. Dimension b applies to the metallized terminal and is measured  
between 0.15mm and 0.30mm from the terminal tip.  
6. The configuration of the pin #1 identifier is optional, but must be  
located within the zone indicated. The pin #1 identifier may be  
either a mold or mark feature.  
7. Dimensions D2 and E2 are for the exposed pads which provide  
improved electrical and thermal performance.  
8. Nominal dimensionsare provided toassistwith PCBLandPattern  
Design efforts, see Intersil Technical Brief TB389.  
9. Features and dimensions A2, A3, D1, E1, P & θ are present when  
Anvil singulation method is used and not present for saw  
singulation.  
10. Depending on the method of lead termination at the edge of the  
package, a maximum 0.15mm pull back (L1) maybe present. L  
minus L1 to be equal to or greater than 0.3mm.  
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.  
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality  
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without  
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and  
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result  
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.  
For information regarding Intersil Corporation and its products, see www.intersil.com  
FN9105.6  
19  
July 25, 2005  

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