DATASHEET

ISL6292B
®
Datasheet
April 19, 2005
FN9139 .1
Li-ion/Li Polymer Battery Charger
Features
The ISL6292B uses Intersil’s patent-pending dual-mode
charge technology to minimize the heat in a linear charger.
The ISL6292B is a modification of the original ISL6292 and
is optimized for cellular phone travel charger applications.
The low-heat generation feature of the dual-mode charger
enables the charger IC to be placed inside the connector of
the travel charger to completely remove the influence of the
adapter cable on the charging performance.
• Complete Charger for Single-Cell Li-ion Batteries
Working with a current-limited ac/dc converter, the dualmode charger charges a Li-ion battery with the same current
profile as a traditional linear charger. The constant charge
current is determined by the current limit of the ac/dc
converter. The constant output voltage is fixed at 4.2V. When
the battery voltage is below 2.8V, the charger preconditions
the battery with a low trickle-charge current. The charge
status is indicated by a tri-color LED. A safety timer prevents
charging a dead battery for an excessively long period.
The ISL6292B also features a thermal foldback function that
automatically reduces the charge current when the internal
die temperature exceeds a 100°C limit to prevent further
temperature rise. This function removes the concern of
thermal failure in the targeted space-limited applications. An
ambient temperature monitoring circuit allows users to set
two separate temperature limit levels, one for during charge
and one for not during charge. The thermally-enhanced QFN
package further improves the thermal performance of the
ISL6292B in space-limited applications.
Ordering Information
PART NUMBER
TEMP. RANGE (°C)
PKG. DWG. #
ISL6292BCR*
-20 to 70
16 Ld 4x4 QFN
ISL6292BCRZ* (Note)
-20 to 70
16 Ld 4x4 QFN
(Pb-free)
*Add “-T” suffix for tape and reel.
NOTE: Intersil Pb-free 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.
• No External Blocking Diode Required
• Very Low Thermal Dual-Mode Operation
• 1% Voltage Accuracy with Remote Sense
• Programmable Current Limit up to 1.5A
• Programmable End-of-Charge Current
• Programmable Safety Timer
• Drives a Tri-Color LED
• Charge Current Thermal Foldback
• NTC Thermistor Interface for Battery Temperature Monitor
• Two-Level Ambient Temperature Setting
• Guaranteed to Operate at 2.65V After Start-Up
• Ambient Temperature Range: -20°C to 70°C
• Thermally-Enhanced QFN Packages
• QFN Package:
- Compliant to JEDEC PUB95 MO-220
QFN - Quad Flat No Leads - Package Outline
- Near Chip Scale Package footprint, which improves
PCB efficiency and has a thinner profile
• Pb-Free Available (RoHS Compliant)
Applications
• Handheld Devices including Medical Handhelds
• PDAs, Cell Phones and Smart Phones
• Portable Instruments, MP3 Players
• Self-Charging Battery Packs
• Stand-Alone Chargers
• USB Bus-Powered Chargers
Related Literature
VIN
VIN
BAT
BAT
ISL6292B TOP VIEW
16
15
14
13
RED 3
10 IMIN
TIME 4
9 IREF
5
6
7
8
V2P9
11 TEMP
EN
12 VSEN
GRN 2
DT
VIN 1
GND
Pinout
• Integrated Pass Element and Current Sensor
1
• 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”
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-352-6832 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2004, 2005. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6292B
Absolute Maximum Ratings
Thermal Information
Supply Voltage (VIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 7V
Output Pin (BAT, VSEN, RED, GRN, DT) . . . . . . . . . . . -0.3 to 5.5V
Signal Pin (EN, TIME TEMP, IREF, IMIN, V2P9) . . . . . . -0.3 to 3.2V
Charge Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6A
ESD Rating
Human Body Model (Per MIL-STD-883 Method 3015.7) . . .3500V
Machine Model (Per EIAJ ED-4701 Method C-111) . . . . . . . .200V
Thermal Resistance (Notes 1, 2)
θJA (°C/W)
θJC (°C/W)
4x4 QFN Package . . . . . . . . . . . . . . . .
41
4
Maximum Junction Temperature (Plastic Package) . . . . . . . . 150°C
Maximum Storage Temperature Range . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C
Recommended Operating Conditions
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . .-20°C to 70°C
Supply Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3V to 6.5V
Recommended Charge Current. . . . . . . . . . . . . . . . 400mA to 1.5A
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. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See
Tech Brief TB379.
2. θJC, “case temperature” location is at the center of the exposed metal pad on the package underside. See Tech Brief TB379.
Electrical Specifications
Typical values are tested at VIN = 5V and 25°C Ambient Temperature, maximum and minimum values are
guaranteed over -10°C to 70°C Ambient Temperature with a supply voltage in the range of 4.3V to 6.5V, unless
otherwise noted.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Rising VIN Threshold
3.0
3.4
4.0
V
Falling VIN Threshold
2.3
2.4
2.7
V
VIN floating or EN pin is floating
-
-
3.0
µA
BAT Pin floating, EN = LOW
-
0.5
-
mA
4.158
4.20
4.242
V
-
190
-
mV
POWER-ON RESET
STANDBY CURRENT
VBAT Pin Sink Current
ISTANDBY
VIN Pin Supply Current
IVIN
VOLTAGE REGULATION
Output Voltage
VCH
Dropout Voltage
VBAT = 3.7V, ICHARGE = 0.65A
CHARGE CURRENT
Charge/Protection Current (Note 3)
ICHARGE
RIREF = 80kΩ, VBAT = 3.7V, VIN = 5V
0.9
1.0
1.1
A
Trickle Charge Current
ITRICKLE
RIREF = 80kΩ, VBAT = 2.0V, VIN = 5V
85
110
135
mA
RIMIN = 133kΩ
40
60
80
mA
VRECHRG
3.85
4.00
4.13
V
VMIN
2.7
2.8
3.2
V
1.44
1.50
1.58
V
-
214
-
mV
0.35
0.38
0.405
V
-
51.4
-
mV
RDT
-
30
100
Ω
Charge Current Foldback Threshold (Note 4)
TFOLD
85
100
115
°C
Current Foldback Gain (Note 4)
GFOLD
-
100
-
mA/°C
End-of-Charge Threshold
RECHARGE THRESHOLD
Recharge Voltage Threshold
TRICKLE CHARGE THRESHOLD
Trickle Charge Threshold Voltage
BATTERY TEMPERATURE MONITORING
Low Temperature Threshold
VTMIN
V2P9 = 3.0V
Low Temperature Hysteresis (Note 4)
High Temperature Threshold
VTMAX
High Temperature Hysteresis (Note 4)
DT Pin MOSFET On Resistance
2
V2P9 = 3.0V
FN9139 .1
April 19, 2005
ISL6292B
Electrical Specifications
Typical values are tested at VIN = 5V and 25°C Ambient Temperature, maximum and minimum values are
guaranteed over -10°C to 70°C Ambient Temperature with a supply voltage in the range of 4.3V to 6.5V, unless
otherwise noted. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
2.4
3.0
3.6
ms
EN Input Low
-
-
0.8
V
EN Pin External Pull Down to Disable
-
-
50
kΩ
OSCILLATOR
Oscillation Period
TOSC
CTIME = 15nF
LOGIC INPUT AND OUTPUT
RED Sink Current
Pin Voltage = 0.8V
5
-
-
mA
GRN Sink Current
Pin Voltage = 0.8V
5
-
-
mA
NOTES:
3. The actual current may be lower due to the thermal foldback.
4. Guaranteed by design, not a tested parameter.
3
FN9139 .1
April 19, 2005
ISL6292B
Pin Description
EN
VIN
EN is the enable logic input. Connect the EN pin to LOW to
enable the charger or leave it floating to disable the charger.
This pin is pulled up to 2.9V when left floating.
VIN is the input power source. Connect to a wall adapter.
RED, GRN
IREF
RED and GRN are two open-drain outputs to drive a red and
a green LED in the same package. The RED and the GRN
pins are guaranteed to be capable of sinking at least 5mA
current.
This is the programming input for the constant charging
current in a linear charger. In the typical application of a
dual-mode charger, the IREF pin programs the trickle charge
current as well as the protection current level.
TIME
IMIN
The TIME pin determines the oscillation period by
connecting a timing capacitor between this pin and GND.
The oscillator provides a time reference for the charger.
IMIN is the programmable input for the end-of-charge
current.
TEMP
GND
TEMP is the input for an external NTC thermistor.
GND is the connection to system ground.
DT
V2P9
DT is the input to set the temperature difference before and
after the charging starts. This pin can also be used as an
indication whether or not the charger is charging.
This is a 2.9V untrimmed voltage output. This pin outputs a
2.9V voltage source when the input voltage is above POR
threshold, independent on the EN pin input. The V2P9 pin
can be used as an indication for adapter presence.
VSEN
VSEN is the battery voltage sensing input. This pin allows
remote sense of the battery pack voltage.
BAT
BAT is the charger output.
Typical Application
Input
C1
R1
BATR3
D1
RS
R5
R4
R2
DT
EN
C TIM E
TIME
RED
GRN
GND
1µF X5R ceramic capacitor
0.1µF X5R ceramic capacitor
22nF X5R or better timing capacitor
dual-color (red and green) LED in one package
80kΩ, 1%
133kΩ, 1%
4
ID
C4
ISL6292B
D2
VSEN
TEMP
RT
C1, C3:
C2, C4:
CTIME :
D1, D2:
RIREF :
RIMIN :
BAT+
C3
V2P9
C2
To Battery
BAT
VIN
R IREF
IREF
R IM IN
IMIN
R1: 41.2kΩ, 1%
R2: TBD, value dependent on the ∆T (2.3kΩ for 20°C)
RT: ECTH-160808-103-J-3800HT, 10kΩ at 25°C, 5%
RS: 1.33kΩ, 1%
R3: 10kΩ, 5% (R3 and C4 are for improving ESD protection)
R4, R5: 330Ω, 5%
FN9139 .1
April 19, 2005
ISL6292B
Block Diagram
Q MAIN
VIN
VMIN
V POR
+
+
-
RIMIN
-
-
CHRG
+
VA
-
I MIN
V IN
+
+
CA
-
Curre nt
Refe re nces
IMIN
Input_OK
VR ECHRG
ISEN
IR
RIREF
100000:1
Curre nt
Mirror
VCH
Q SEN
IT
IREF
V2P9
Re ference s
Tem pera ture
Monitoring
VPOR
C1
BAT
VSEN
100mV
VCH
+
Trickle /Fa st
I SEN
MIN_I
+
Recha rge
UnderTe m p
NTC
Interfa ce
DT
OSC
GND
VRECHRG
-
V2P
8
TIME
VM IN
+
-
TEMP
-
Minbat
LOGIC
OverTe mp
RED
GRN
COUNTER
Input_OK
EN
5
FN9139 .1
April 19, 2005
ISL6292B
Flow Chart
Anytime POR
and Enable
occurs
TEMP fault removed
TEMP FAULT
Charger: OFF
LED: YELLOW
TRICKLE CHARGE
Charger: ON
LED: RED
TEMP fault
TEMP fault
VBAT < 2.8V when 1/8 TIMEOUT
completes
TIMEOUT FAULT
Charger: OFF
LED: YELLOW
VBAT > 2.8V before 1/8 TIMEOUT
completes
FAST CHARGE
Charger: ON
LED: RED
TIMEOUT
completes and
VBAT < VRECHRG
VBAT > VRECHRG and ICHG < IMIN
and
TIMEOUT not completed
TEMP fault
CHARGE COMPLETES BUT NOT
TERMINATES
Charger: ON
LED: GREEN
TIMEOUT
completes
TEMP fault
removed
TEMP FAULT
Charger: OFF
LED: YELLOW
CHARGE TERMINATES
Charger: OFF
LED: GREEN
TIMEOUT
completes and
VBAT > VRECHRG
CHARGE TERMINATES
Charger: OFF
LED: GREEN
TEMP fault
VBAT < VRECHRG
TEMP fault
removed
TEMP FAULT
Charger: OFF
LED: YELLOW
RECHARGE
Charger: ON
LED: GREEN
TIMEOUT completes
TEMP fault
6
FN9139 .1
April 19, 2005
ISL6292B
Theory of Operation
The ISL6292B is based on the Intersil Patent-pending
dual-mode charging technology. The dual-mode technology
generates very low heat, which enables the charger to be
used in space-limited applications.
To take advantage of the low-heat feature, a current-limited
ac/dc converter is required as the power supply to the
charger. The current-limited supply has the I-V
characteristics shown in Figure 1. The supply is a dc source
before the load current reaches the limited current ILIM.
Once the current limit is reached, the supply current cannot
increase further; instead, the supply voltage falls. The
current-limited supply is equivalent to a voltage source with
an equivalent output impedance or a current source,
depending on the region it operates at, as shown in Figure 1.
The ISL6292B charges a battery with the traditional constant
current/constant voltage (CC/CV) profile. The constant
current is determined by the current limit ILIM of the supply
during the constant-current charge mode. To ensure dualmode operation, the current protection level set by the IREF
pin should be higher than ILIM. In the constant-voltage
charge mode, the battery voltage is regulated at 4.2V. When
the battery voltage is below the VMIN given in the Electrical
Specification, the charger preconditions the battery using
trickle charge mode. The trickle-charge current is 10% of the
protection current level programmed by the IREF pin.
Figure 2 shows the typical waveforms in a charge cycle of
the dual mode operation. When the battery is below VMIN,
the charge current is 10% of IREF set by the IREF pin. Since
the charge current is much less than the ILIM, the ac/dc
converter operates in the voltage source region. Once the
battery voltage exceeds VMIN, the charger starts to fully turn
on the internal P-channel power MOSFET. The ac/dc
converter operates in the current-limited region and its
voltage is pulled down to a level slightly higher than the
battery voltage. As shown in Figure 2, the charge current is
ILIM and is lower than IREF. As the battery voltage reaches
the 4.2V VCH, the charge current starts to decrease. The
ac/dc supply moves out of the current-limit region and
becomes a voltage source again. When the charge current
reaches a programmable end-of-charge (EOC) level set by
the IMIN pin, the charger sends out an EOC indication. The
real termination of the charger happens at the end of a total
charge time set by the TIME pin.
The power dissipation is also shown in Figure 2. The power
dissipation in both the trickle mode and the constant-current
(CC) mode are very low. The possible peak power occurs at
the transition from the CC mode to the constant-voltage (CV)
mode. This peak power is much lower than the peak power
normally seen in a linear charger and can be further reduced
by properly designing the ac/dc converter. One simple
approach is to design the ac/dc converter output voltage just
high enough to fully charge the battery (normally lower than
5V). More information can be found in the ISL6292
datasheet available at http://www.intersil.com. To ensure the
thermal safety, the ISL6292B has an internal thermal foldback function that automatically reduces the charge current
if the internal temperature typically rises above 100°C.
The ISL6292B offers many other features. The trickle
current, the CC charge current, and the end-of-charge
(EOC) current are all programmable. A thermal foldback
function monitors the internal temperature and reduces the
charge current when the internal temperature rises above
100°C to prevent further temperature rise. A safety timer
sets the charge time limit for both trickle mode and fast mode
charge. When the battery voltage drops after the charge
cycle terminates, the charger automatically starts recharging
the battery to full. Two indication pins are designed to drive a
tri-color LED (a red and a green LED in the same package).
A simple thermistor circuit interface allows the user to set a
different level of ambient temperature before and after the
charger starts. All these features are described in detail in
the Application Information section.
Trickle
Mode
VIN
V CH
Constant
Current Mode
Constant
Voltage Mode
Inhibit
Input Voltage
Battery Voltage
V M IN
V NL
C
r O = (VNL - VFL )/ILIM
VFL
B
IREF
ILIM
Charge Current
rO
IREF /10
I LIM
VNL
A
ILIM
FIGURE 1. THE I-V CHARACTERISTICS OF THE CURRENTLIMITED AC/DC CONVERTER.
7
P1
P2
Power Dissipation
TIMEOUT
FIGURE 2. TYPICAL CHARGE CURVES USING A CURRENTLIMITED ADAPTER.
FN9139 .1
April 19, 2005
ISL6292B
Applications Information
EOC Current and RIMIN Selection
Power-On Reset (POR)
The EOC current is programmed by the IMIN pin and can be
calculated by the following equation:
The ISL6292B has a 3.4V rising POR threshold. Before the
input voltage reaches the POR threshold, the 2.9V V2P9 pin
outputs 0V and the charger is disabled. Once the POR
threshold is reached, the V2P9 pin outputs 2.9V, the opendrain MOSFET on the DT pin is turned on, and the ambient
temperature monitoring circuit starts to function. After a
delay and after the input voltage rises above the battery
voltage, the charger control circuit starts to work and the DT
pin impedance becomes high. Figure 3 shows the sequence
of the events at power on. The POR has a falling threshold
of 2.4V typically. At power on, all counters are reset to zero.
Charge Current and RIREF Selection
When the ISL6292B is used as a traditional linear charger,
the RIREF sets the constant charge current. The trickle
charge current is 10% of the CC current IREF. When working
with a current-limited supply, the CC current is determined
by the supply limited current ILIM. IREF needs to be
programmed higher than ILIM and is used as an overcurrent
protection. Taking into account the tolerance of both the ILIM
and IREF, it is recommended the IREF be programmed at
least 30% higher than the ILIM. IREF can be found by the
following equation:
5
0.8V
I REF = ----------------- × 10 ( A )
R IREF
(EQ. 1)
(EQ. 2)
The ISL6292B has a comparator with 100mV offset voltage
to ensure the input voltage is higher than the battery voltage
before charging starts (see the Block Diagram). This
condition requires ILIM be higher than 400mA. The upper
limit for ILIM is 1.5A.
VIN
(EQ. 3)
The EOC current has a programming range up to 400mA.
To qualify as an EOC condition, the charge current needs to
drop below the IMIN level and stay below the IMIN level for
more than three to four cycles of the internal oscillator;
additionally, the battery voltage rises above the recharge
threshold given in the Electrical Specification table.
Internal Oscillator
The internal oscillator establishes a timing reference. The
oscillation period is programmable with an external timing
capacitor, CTIME, as shown in Typical Applications. The
oscillator charges the timing capacitor to 1.5V and then
discharges it to 0.5V in one period, both with 10µA current.
The period TOSC is:
6
T OSC = 0.2 ⋅ 10 ⋅ C TIME
( sec onds )
(EQ. 4)
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.
Total Charge Time and CTIME Selection
The total charge time for the CC mode and CV mode is
limited to a length of TIMEOUT, which can be found by:
The trickle charge current is 10% of IREF, that is,
4
0.8V
I Trickle = ----------------- × 10 ( A )
R IREF
4
0.8V
I MIN = ---------------- × 10 ( A )
R IMIN
C TIME
TIMEOUT = 14 ⋅ -----------------1nF
( minutes )
VIN
POR
Th re sh o ld
V2P9
Ch arg e
Cycle
(EQ. 5)
Ch arg e
Cycle
DT
Imp e d .
POR
RED
M IN
V2P9
15 Cycle s to
1/8 TIM EOUT
GRN
DT
Imped
VBAT
Charger
Start
I CHG
V RECHRG
2.8V V M IN
I M IN
t0
FIGURE 3. EVENT SEQUENCE AT POWER UP
8
15
Cycle s
t1 t2 t3
t4
t5
t6 t7
t8
FIGURE 4. OPERATION WAVEFORMS
FN9139 .1
April 19, 2005
ISL6292B
BAT
VSEN
2.9V
R1
10Ω
Under
Temp CP1
R2
R1
100K
VTM IN
+
V2P9
R2
75K
To TEMP Pin
RU
TEMP
-
VA
+
Q1
VREF
Enable
R3
Over
Temp
Q1
CP2
+
R3
25K
V TM AX
Q2
RT
R4
4K
DT
FIGURE 5. THE INTERNAL VOLTAGE FEEDBACK CIRCUIT
Q3
CHG
CTIME is the timing capacitor shown in the Typical
Application circuit. A 1nF capacitor leads to 14 minutes of
TIMEOUT. For example, a 15nF capacitor sets the
TIMEOUT to be 3.5 hours. The charger is terminated when
the TIMEOUT is reached.
The trickle mode charge has a time limit of 1/8 TIMEOUT. If
the battery voltage does not reach VMIN within that limit, a
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.
GND
RD
FIGURE 6. THE INTERNAL AND EXTERNAL CIRCUIT FOR
THE NTC INTERFACE
TABLE 1. LED INDICATION SUMMARY
STATUS
RED GRN
INDICATION
Charging
L
H
Red
Full Charge (EOC), or recharging
H
L
Green
Recharge Threshold
Trickle TIMEOUT Error
L
L
Yellow (Latched)
The charger terminates when the TIMEOUT limit expires.
After the termination, if the battery is below the recharge
threshold given in the Electrical Specification table, the
charger starts a re-charge cycle.
Over/Under Ambient Temperature
L
L
Yellow
No Battery
H
H
Off
LED Indications
RED and GRN are two open-drain outputs that directly drive
a tri-color LED. At the moment when the power is applied or
when the charger is enabled through the EN pin, the charger
starts to charge and the RED indication pin outputs a low
impedance to drive a red LED. Once the charge finishes
(either when the EOC condition is qualified or when the
TIMEOUT completes), the GRN pin turns on to drive a green
LED and the red LED is off. The green LED remains on
unless the input power is recycled, or when the EN pin is
toggled, or a fault case happens. When a recharge occurs,
the indication remains in green.
When a fault case happens, both the RED and the GRN pins
are on to indicate a yellow color. If the FAULT is a TIMEOUT
fault, the yellow indication is latched and can only be reset
through the EN pin or the input power. If the FAULT is an
ambient temperature FAULT, the charger restarts after the
fault condition is removed. When not powered or when not
enabled, both LEDs are off. Table 1 summarizes the LED
indications.
9
VSEN Pin
The VSEN pin allows remote sensing of the battery voltage
to minimize the resistive voltage drop between the charger
output and the battery positive terminal. Figure 5 shows the
internal voltage feedback circuit. In applications that the
remote sense pin goes through a connector, a local lowvalue resistor is recommended, as the R1 shown in Figure 5,
in case the connector has bad contact. The sum of R2 and
R3 is 75kΩ, therefore, a 10Ω R1 is negligible in output
voltage accuracy.
Ambient Temperature Sensing
The TEMP pin is used to set the ambient temperature range
that allows charging the battery. Typically, an NTC (negative
temperature coefficient) resistor is mounted on the printed
circuit board (PCB) to monitor the ambient temperature. Due
to the self-heating of the PCB during charging, the ISL6292B
provides the DT pin to set a higher temperature threshold
after the charger starts.
Figure 6 shows the internal circuit for the ambient
temperature sensing function. The two comparators form a
window comparator whose high-threshold is VTMIN and lowthreshold is VTMAX. These two thresholds are given in the
Electrical Specifications. The two MOSFETs (Q1 and Q2)
FN9139 .1
April 19, 2005
ISL6292B
NOTCHARGE
V2P9
V2P9
45 oC
40 oC
TEMP
TEMP
Less than 2 °C
RT
RT
NOTCHARGE
45 C + ∆T
RU
RU
CHARGE
o
0 oC
-5 oC
DT
RD
RQ3
GND
GND
(A)
(B)
FIGURE 7. EQUIVALENT CIRCUITS FOR THE NTC DIVIDER
(A) BEFORE CHARGING STARTS
(B) DURING CHARGING.
create a hysteresis for each comparator respectively. The
DT pin is shorted to GND via the internal Q3 MOSFET when
the charger is not charging, resulting in the equivalent circuit
shown in Figure 7 (A). The on-resistance of Q3 is typically
50Ω and is negligible compared to the external resistors.
When the charger starts to charge, Q3 is turned off to set a
higher temperature range determined by the external
resistor RD. The equivalent circuit is shown in Figure 7 (B).
The DT pin allows the user to set up a higher shut down
ambient temperature after the charger starts up.
The selection of RU and RT uses the same procedure
described in the ISL6292 datasheet. The selection RD
follows the following equation:
RD = RT,@45°C - RT,@(45°C + ∆T)
where RT,@45°C is the thermistor resistance at 45°C and the
RT,@(45°C + ∆T) is the resistance at 45°C + ∆T. Figure 8
shows the temperature windows before, during, and after
charging. Before and after charging, the temperature window
is -5°C to 45°C with 5°C hysteresis. During charging, the
high temperature limit changes to 45°C + ∆T. If this limit is
exceeded, the charger is stopped and the temperature has
to come back to below 40°C for the charging to be allowed
again. The low temperature limit is also increased. However,
the RD typically has a much lower resistance than the NTC
at low temperature, therefore, the influence on the
temperature threshold is not as much as at high
temperature. Typically, the low temperature threshold is
raised by less than 2°C, as shown in Figure 8.
Charge Current Thermal Foldback
The thermal foldback function monitors the die temperature
and reduces the charge current when the die temperature
rises above 100°C to prevent further temperature rise. The
charge current reduces at a rate of 100mA/°C after
exceeding 100°C. For a charger with the constant charge
current set at 1A, the charge current is reduced to zero when
10
FIGURE 8. BOARD TEMPERATURE MONITORING WHEN
THE CHARGE IS NOT CHARGING, THE
TEMPERATURE WINDOW IS -5°C AND 45°C.
ONCE THE CHARGER STARTS, THE
TEMPERATURE WINDOW IS 1.X°C TO 45°C+ ∆T.
the internal temperature rises to 110°C. The actual charge
current settles between 100°C to 110°C.
Usually the charge current should not drop below IMIN
because of the thermal foldback. For some extreme cases if
that does happen, the charger does not indicate end-ofcharge unless the battery voltage is already above the
recharge threshold.
2.9V Bias Voltage
The ISL6292B provides a 2.9V 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.
EN Pin
The EN pin allows direct interface to the battery ID pin of a
battery pack. The battery ID pin is connected with a resistor
of a value less than 27kΩ to ground inside the battery pack.
When the battery is not attached, the EN pin is pulled up by
an internal source to the V2P9 pin to disable the charger.
The 2.9V internal regulator is on as long as the input power
is applied, independent of the EN input. Table 2 summarizes
the status of each pin when the IC is disabled.
TABLE 2. SUMMARY OF PIN BEHAVIOR WHEN THE IC IS
DISABLED BY THE EN PIN
PIN
BEHAVIOR
V2P9
Outputs 2.9V.
RED
High impedance
GRN
High impedance
DT
Low impedance
IREF
Outputs 0.8V
IMIN
Outputs 0.8V
TEMP
The temperature monitoring circuit remains functioning.
FN9139 .1
April 19, 2005
ISL6292B
Board Layout Recommendations
The ISL6292B is targeted for space-limited applications. 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 4x4
QFN package are able to have 5 vias. As much copper as
possible should be connected to the exposed pad to
minimize the thermal impedance. Refer to the ISL6292B
evaluation board for layout examples.
11
FN9139 .1
April 19, 2005
ISL6292B
Quad Flat No-Lead Plastic Package (QFN)
Micro Lead Frame Plastic Package (MLFP)
L16.4x4
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
(COMPLIANT TO JEDEC MO-220-VGGC ISSUE C)
MILLIMETERS
SYMBOL
MIN
NOMINAL
MAX
NOTES
A
0.80
0.90
1.00
-
A1
-
-
0.05
-
A2
-
-
1.00
A3
b
0.23
D
0.28
9
0.35
5, 8
4.00 BSC
D1
D2
9
0.20 REF
-
3.75 BSC
1.95
2.10
9
2.25
7, 8
E
4.00 BSC
-
E1
3.75 BSC
9
E2
1.95
e
2.10
2.25
7, 8
0.65 BSC
-
k
0.25
-
-
-
L
0.50
0.60
0.75
8
L1
-
-
0.15
10
N
16
2
Nd
4
3
Ne
4
3
P
-
-
0.60
9
θ
-
-
12
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 dimensions are provided to assist with PCB Land Pattern
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.
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12
FN9139 .1
April 19, 2005
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