LTC4002ES8-4.2#TR [Linear]
LTC4002 - Standalone Li-Ion Switch Mode Battery Charger; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C;
| 型号： | LTC4002ES8-4.2#TR |
| 厂家： | 
Linear |
| 描述： | LTC4002 - Standalone Li-Ion Switch Mode Battery Charger; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C 电池 开关 |
| 文件： | 总16页 (文件大小：168K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC4002
Standalone Li-Ion
Switch Mode Battery Charger
U
FEATURES
DESCRIPTIO
■
Wide Input Supply Range:
The LTC®4002 is a complete battery charger controller for
one (4.2V) or two (8.4V) cell lithium-ion batteries. With a
500kHz switching frequency, the LTC4002 provides a
small, simple and efficient solution to fast charge Li-Ion
batteriesfromawiderangeofsupplyvoltages. Anexternal
senseresistorsetsthechargecurrentwith±5%accuracy.
An internal resistor divider and precision reference set the
final float voltage to 4.2V per cell with ±1% accuracy.
4.7V to 22V – 4.2 Version
8.9V to 22V – 8.4 Version
■
High Efficiency Current Mode PWM Controller with
500kHz Switching Frequency
±1% Charge Voltage Accuracy
■
■
End-of-Charge Current Detection Output
■
3 Hour Charge Termination Timer
■
Constant Switching Frequency for Minimum Noise
Whentheinputsupplyisremoved,theLTC4002automati-
callyentersalowcurrentsleepmode,droppingthebattery
drain current to 10µA. An internal comparator detects the
near end-of-charge condition while an internal timer sets
thetotalchargetimeandterminatesthechargecycle.After
the charge cycle ends, if the battery voltage drops below
4.05Vpercell, anewchargecyclewillautomaticallybegin.
■
±5% Charge Current Accuracy
■
Low 10µA Reverse Battery Drain Current
■
Automatic Battery Recharge
■
Automatic Shutdown When Input Supply is Removed
■
Automatic Trickle Charging of Low Voltage Batteries
■
Battery Temperature Sensing and Charge
Qualification
■
■
TheLTC4002isavailableinthe8-leadSOand10-leadDFN
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Stable with Ceramic Output Capacitor
8-Lead SO and 10-Lead DFN Packages
U
APPLICATIO S
■
Portable Computers
■
Charging Docks
■
Handheld Instruments
U
TYPICAL APPLICATIO
1.5A Single Cell Li-Ion Battery Charger
Efficiency vs Input Voltage
V
IN
100
(CURVES INCLUDE
INPUT DIODE)
5V TO 22V
90
V
BAT
= 4V
0.1µF
10µF
V
CC
BAT
2k
GATE
V
= 3.8V
80
70
60
BAT
LTC4002ES8-4.2
CHARGE
STATUS
6.8µH
CHRG
SENSE
68mΩ
22µF
COMP
NTC
BAT
GND
5
10
15
INPUT VOLTAGE (V)
20
25
+
0.47µF
Li-Ion
4002 TA02
BATTERY
2.2k
10k
NTC
4002 TA01
T
NTC: DALE NTHS-1206N02
4002f
1
LTC4002
W W U W
ABSOLUTE AXI U RATI GS (Note 1)
Supply Voltage (VCC) .............................................. 24V
GATE .................................................. (VCC –8V) to VCC
BAT, SENSE .............................................. –0.3V to 14V
CHRG, NTC ................................................. –0.3V to 8V
Operating Temperature Range (Note 4) .. –40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
Lead Temperature (S8 Package)
(Soldering, 10 sec) ........................................... 300°C
U
W
U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
ORDER PART
NUMBER
ORDER PART
TOP VIEW
NUMBER
COMP
1
2
3
4
5
10 NC
COMP
1
2
3
4
8
7
6
5
NTC
V
9
8
7
6
NTC
CC
LTC4002EDD-4.2
LTC4002EDD-8.4
LTC4002ES8-4.2
LTC4002ES8-8.4
11
GATE
PGND
SGND
SENSE
BAT
V
SENSE
BAT
CC
GATE
GND
CHRG
CHRG
DD PART MARKING
S8 PART MARKING
DD PACKAGE
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 110°C/W
10-LEAD (3mm × 3mm) PLASTIC DFN
LAGG
LBGY
400242
400284
TJMAX = 125°C, θJA = 43°C/W
EXPOSED PAD IS GND (PIN 11)
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
(LTC4002-4.2) The ● denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at TA = 25°C. VCC = 10V unless otherwise noted.
SYMBOL PARAMETER
DC Characteristics
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
V
Supply Voltage
Supply Current
●
4.7
22
V
CC
CC
CC
I
Current Mode
Shutdown Mode
Sleep Mode
3
3
10
5
5
20
mA
mA
µA
CC
V
V
Battery Regulated Float Voltage
Constant Current Sense Voltage
5V ≤ V ≤ 22V (Note 2)
4.168
4.158
4.2
4.232
4.242
V
V
BAT(FLT)
CC
●
3V ≤ V
≤ 4V (Note 3)
0°C ≤ T ≤ 85°C
●
●
93
90
100
107
110
mV
mV
SNS(CHG)
BAT
A
–40°C ≤ T ≤ 85°C
A
V
V
V
Trickle Current Sense Voltage
V
V
V
= 0V (Note 3)
Rising
5
10
2.9
4.2
200
360
250
100
25
15
3.05
4.5
mV
V
SNS(TRKL)
TRKL
BAT
BAT
Trickle Charge Threshold Voltage
2.75
3.9
V
V
Undervoltage Lockout Threshold Voltage
Undervoltage Lockout Hysteresis Voltage
Rising
CC
V
UV
CC
CC
∆V
mV
mV
mV
µA
µA
V
UV
MSD
V
V
Manual Shutdown Threshold Voltage
Automatic Shutdown Threshold Voltage
COMP Pin Output Current
COMP Pin Falling
200
500
V
V
V
– V
BAT
ASD
CC
I
I
= 1.2V
= 1V
COMP
CHRG
COMP
CHRG
CHRG Pin Weak Pull-Down Current
CHRG Pin Output Low Voltage
End-of-Charge Ratio
15
10
35
0.3
32
10
V
I
= 1mA
CHRG
0.15
25
CHRG
R
V
/V
SNS(EOC) SNS(CHG)
%
EOC
t
Charge Time Accuracy
%
TIMER
4002f
2
LTC4002
ELECTRICAL CHARACTERISTICS
(LTC4002-4.2) The ● denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at TA = 25°C. VCC = 10V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
75
TYP
MAX
95
UNITS
I
NTC Pin Output Current
V
= 0.85V
●
●
85
µA
NTC
NTC
V
NTC Pin Threshold Voltage (Hot)
V
Falling
340
355
25
370
mV
mV
NTC-HOT
NTC
Hysteresis
Rising
V
NTC Pin Threshold Voltage (Cold)
V
●
2.428
100
2.465
170
2.502
200
1
V
mV
NTC-COLD
NTC
Hysteresis
∆V
RECHRG
Recharge Battery Voltage Offset from Full
Charged Battery Voltage
V
– V , V Falling
RECHRG BAT
150
mV
BAT(FULLCHARGED)
I
CHRG Pin Leakage Current
V
= 8V, Charging Stops
µA
LEAK
CHRG
Oscillator
f
Switching Frequency
Maximum Duty Cycle
450
500
550
100
kHz
%
OSC
DC
Gate Drive
t
t
Rise Time
C
C
V
= 2000pF, 10% to 90%
= 2000pF, 90% to 10%
20
50
ns
ns
V
r
f
GATE
GATE
Fall Time
∆V
∆V
∆V
Output Clamp Voltage
Output High Voltage
Output Low Voltage
– V , V ≥ 9V
GATE CC
●
●
●
8
GATE
CC
∆V
∆V
= V – V , V ≥ 7V
GATE CC
0.3
V
GATEHI
GATELO
GATEHI
GATELO
CC
= V – V
, V ≥ 7V
GATE CC
4.5
V
CC
(LTC4002-8.4) The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at
TA = 25°C. VCC = 12V unless otherwise noted.
SYMBOL PARAMETER
DC Characteristics
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
V
Supply Voltage
Supply Current
●
8.9
22
V
CC
CC
CC
I
Current Mode
Shutdown Mode
Sleep Mode
3
3
10
5
5
20
mA
mA
µA
CC
V
V
Battery Regulated Float Voltage
Constant Current Sense Voltage
9V ≤ V ≤ 22V (Note 2)
8.336
8.316
8.4
8.464
8.484
V
V
BAT(FLT)
CC
●
●
95
93
100
100
105
107
mV
mV
SNS(CHG)
6V ≤ V
≤ 8V (Note 3)
BAT
V
V
V
Trickle Current Sense Voltage
V
V
V
= 0V (Note 3)
Rising
5
10
5
15
5.3
8.5
mV
V
SNS(TRKL)
TRKL
BAT
BAT
Trickle Charge Threshold Voltage
4.7
V
V
Undervoltage Lockout Threshold Voltage
Undervoltage Lockout Hysteresis Voltage
Rising
CC
7.5
500
350
250
100
25
V
UV
CC
CC
∆V
mV
mV
mV
µA
µA
V
UV
V
V
Manual Shutdown Threshold Voltage
Automatic Shutdown Threshold Voltage
COMP Pin Output Current
COMP Pin Falling
200
500
MSD
V
V
V
– V
BAT
ASD
CC
I
I
= 1.2V
= 1V
COMP
CHRG
COMP
CHRG
CHRG Pin Weak Pull-Down Current
CHRG Pin Output Low Voltage
End-of-Charge Ratio
15
5
35
0.3
15
10
95
V
I
= 1mA
CHRG
0.15
10
CHRG
R
V
/V
SNS(EOC) SNS(CHG)
%
EOC
TIMER
NTC
t
I
Charge Time Accuracy
%
NTC Pin Output Current
V
= 0.85V
●
75
85
µA
NTC
4002f
3
LTC4002
ELECTRICAL CHARACTERISTICS
(LTC4002-8.4) The ● denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at TA = 25°C. VCC = 12V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
Falling
Hysteresis
MIN
TYP
MAX
UNITS
V
NTC Pin Threshold Voltage (Hot)
V
●
●
340
355
25
370
mV
mV
NTC-HOT
NTC
V
NTC Pin Threshold Voltage (Cold)
V
Rising
2.428
200
2.465
170
2.502
400
1
V
mV
NTC-COLD
NTC
Hysteresis
∆V
RECHRG
Recharge Battery Voltage Offset from Full
Charged Battery Voltage
V
V
– V , V Falling
RECHRG BAT
300
mV
BAT(FULLCHARGED)
I
CHRG Pin Leakage Current
= 8V, Charging Stops
µA
LEAK
CHRG
Oscillator
f
Switching Frequency
Maximum Duty Cycle
450
500
550
100
kHz
%
OSC
DC
Gate Drive
t
t
Rise Time
C
C
V
= 2000pF, 10% to 90%
= 2000pF, 90% to 10%
20
50
ns
ns
V
r
f
GATE
GATE
CC
Fall Time
∆V
∆V
∆V
Output Clamp Voltage
Output High Voltage
Output Low Voltage
– V
●
●
●
8
GATE
GATE
∆V
∆V
= V – V
GATE
0.3
V
GATEHI
GATELO
GATEHI
GATELO
CC
= V – V
4.5
V
CC
GATE
Note 1: Absolute Maximum Rating are those values beyond which the life
of a device may be impaired.
Note 2: The LTC4002 is tested with Test Circuit 1.
Note 3: The LTC4002 is tested with Test Circuit 2.
Note 4: The LTC4002 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
U W
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C, VCC = 10V unless otherwise noted.
Oscillator Frequency
vs Temperature
Supply Current vs Temperature
Supply Current vs VCC
4.0
3.5
550
500
450
4
CURRENT MODE
3
3.0
2.5
2
50
TEMPERATURE (°C)
100 125
–25
0
50
75 100 125
–50 –25
0
25
75
15
(V)
–50
25
5
20
25
10
TEMPERATURE (°C)
V
CC
4002 G01
4002 G03
4002 G02
4002f
4
LTC4002
U W
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C, VCC = 10V unless otherwise noted.
Undervoltage Lockout Threshold
vs Temperature
CHRG Pin Output Low Voltage
vs VCC
Oscillator Frequency vs VCC
510
150
8
7
6
5
4
I
= 1mA
V
CC
RISING
LOAD
LTC4002-8.4
500
140
LTC4002-4.2
490
130
15
(V)
20
15
(V)
20
5
25
–25
0
50
75 100 125
5
25
10
–50
25
10
V
V
TEMPERATURE (°C)
CC
CC
4002 G04
4002 G06
4002 G05
CHRG Pin Weak Pull-Down
Current vs Temperature
CHRG Output Pin Weak Pull-Down
Current vs VCC
CHRG Pin Output Low Voltage
vs Temperature
180
140
100
29
25
21
28
25
22
I
= 1mA
V
= 8V
V
CHRG
= 8V
LOAD
CHRG
–25
0
50
75 100 125
–25
0
50
75 100 125
5
10
15
(V)
20
25
–50
25
–50
25
V
TEMPERATURE (°C)
TEMPERATURE (°C)
CC
4002 G07
4002 G08
4002 G09
Recharge Voltage Offset
Per Cell from Full Charged
Voltage vs Temperature
Recharge Voltage Offset from Full
Charged Voltage vs VCC
Recharge Voltage Offset from Full
Charged Voltage vs VCC
320
300
190
150
110
160
150
LTC4002-8.4
LTC4002-4.2
280
140
15
(V)
20
–25
0
50
75 100 125
15
(V)
5
10
25
–50
25
5
20
25
10
V
TEMPERATURE (°C)
V
CC
CC
4002 G12
4002 G10
4002 G11
4002f
5
LTC4002
U W
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C, VCC = 10V unless otherwise noted.
Current Mode Sense Voltage
vs VCC
Current Mode Sense Voltage
vs VCC
Current Mode Sense Voltage
vs Temperature
102
102
104
100
96
V
= 4V
V
= 8V
BAT
BAT
LTC4002-8.4
LTC4002-4.2
100
100
98
98
15
(V)
20
15
(V)
–25
0
50
75 100 125
5
10
25
5
20
25
–50
25
10
V
V
TEMPERATURE (°C)
CC
CC
4002 G14
4002 G15
4002 G13
COMP Pin Output Current
vs VCC
COMP Pin Output Current
vs Temperature
NTC Pin Output Current
vs VCC
102
100
86
85
104
100
96
V
COMP
= 0V
V
= 0V
NTC
V
COMP
= 0V
98
84
15
(V)
20
15
(V)
20
5
25
–25
0
50
75 100 125
5
25
10
–50
25
10
V
V
TEMPERATURE (°C)
CC
CC
4002 G16
4002 G18
4002 G17
Trickle Charge Voltage
vs Temperature
Trickle Charge Voltage
vs VCC
Trickle Charge Voltage
vs Temperature
3.0
2.9
3.0
2.9
2.8
5.2
5.0
4.8
LTC4002-4.2
LTC4002-4.2
LTC4002-8.4
2.8
15
(V)
20
–25
0
50
75 100 125
5
10
25
–25
0
50
75 100 125
–50
25
–50
25
V
TEMPERATURE (°C)
TEMPERATURE (°C)
CC
4002 G20
4002 G19
4002 G21
4002f
6
LTC4002
U W
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C, VCC = 10V unless otherwise noted.
Trickle Charge Sense Voltage
vs Temperature
Trickle Charge Voltage
vs VCC
Trickle Charge Sense Voltage
vs VCC
5.2
10.4
10.0
9.6
11
LTC4002-8.4
V
= 2.5V
V
= 2.5V
BAT
BAT
LTC4002-4.2
LTC4002-4.2
5.0
10
4.8
9
15
(V)
20
5
25
–25
0
50
75 100 125
10
–50
25
15
(V)
5
20
25
10
V
TEMPERATURE (°C)
V
CC
CC
4002 G22
4002 G23
4002 G24
NTC Pin Output Current
vs Temperature
Trickle Charge Sense Voltage
vs Temperature
Trickle Charge Sense Voltage
vs VCC
10.4
10.0
9.6
89
85
81
11
10
V
= 4V
V
= 4V
V
= 0V
BAT
BAT
NTC
LTC4002-8.4
LTC4002-8.4
9
–25
0
50
75 100 125
–25
0
50
75 100 125
–50
25
15
(V)
–50
25
5
20
25
10
TEMPERATURE (°C)
TEMPERATURE (°C)
V
CC
4002 G25
4002 G27
4002 G26
End-of-Charge Ratio
vs Temperature
End-of-Charge Ratio
vs VCC
29
25
21
28
LTC4002-4.2
LTC4002-4.2
25
22
–25
0
50
75 100 125
5
10
15
(V)
20
25
–50
25
V
TEMPERATURE (°C)
CC
4002 G28
4002 G29
4002f
7
LTC4002
U W
TYPICAL PERFOR A CE CHARACTERISTICS TA = 25°C, VCC = 10V unless otherwise noted.
End-of-Charge Ratio
vs Temperature
End-of-Charge Ratio
vs VCC
14
13
12
11
10
9
14
13
12
11
10
9
LTC4002-8.4
LTC4002-8.4
8
8
7
7
6
6
5
10
15
(V)
20
25
–25
0
50
75 100 125
–50
25
V
TEMPERATURE (°C)
CC
4002 G31
4002 G30
U
U
U
(DFN/SO-8)
PI FU CTIO S
COMP (Pin 1/Pin 1): Compensation, Soft-Start and Shut-
downControlPin.TheCOMPpinisthecontrolsignalofthe
innerloopofthecurrentmodePWM.Chargingbeginswhen
theCOMPpinreaches800mV.Therecommendedcompen-
sation components are a 0.47µF (or larger) capacitor and
a 2.2k series resistor. A 100µA current into the compen-
sation capacitor also sets the soft-start slew rate. Pulling
the COMP pin below 360mV will shut down the charger.
currentdropsbelowtheEnd-of-Chargethresholdformore
than 120µs, the N-channel MOSFET turns off and a 25µA
current source is connected from the CHRG pin to GND.
When the timer runs out or the input supply is removed,
the 25µA current source is turned off and the CHRG pin
becomes high impedance.
BAT (Pin 7/Pin 6): Battery Sense Input. A bypass capaci-
tor of 22µF is required to minimize ripple voltage. An
internal resistor divider, which is disconnected in sleep
mode, sets the final float voltage at this pin. If the battery
connection is opened when charging, an overvoltage
circuit will limit the charger output voltage to 10% above
the programmed float voltage.
VCC (Pin 2/Pin 2): Positive Supply Voltage Input. VCC can
range from VBAT(FLT) + 0.5V to 22V. A 0.1µF or higher ca-
pacitor is required at the VCC pin with the lead length kept
to a minimum. A 10µF low ESR capacitor is also required
at the source pins of the power P-channel MOSFET.
GATE (Pin 3/Pin 3): Gate Drive Output. Driver Output for
theP-ChannelMOSFET. Thevoltageatthispinisinternally
clamped to 8V below VCC, allowing a low voltage MOSFET
with gate-to-source breakdown voltage of 8V or less to be
used.
When VBAT is within 250mV of VCC, the LTC4002 is forced
into sleep mode, dropping ICC to 10µA.
SENSE(Pin8/Pin7):CurrentAmplifierSenseInput.Asense
resistor, RSENSE, must be connected between the SENSE
and BAT pins. The maximum charge current is equal to
PGND, SGND, Exposed Pad, GND (Pins 4, 5, 11/Pin 4):
ICGround.Theexposedpad(DFN)mustbesolderedtoPCB
ground to provide both electrical contact and optimum
thermal performance.
100mV/RSENSE.
NTC(Pin9/Pin8):NTC(NegativeTemperatureCoefficient)
Thermistor Input. With an external 10kΩ NTC thermistor
to ground, this pin senses the temperature of the battery
pack and stops the charger when the temperature is out of
range. When the voltage at this pin drops below 355mV at
CHRG (Pin 6/Pin 5): Open-Drain Charge Status Output.
When the battery is being charged, the CHRG pin is pulled
low by an internal N-channel MOSFET. When the charge
4002f
8
LTC4002
U
U
U
PI FU CTIO S (DFN/SO-8)
hottemperatureorrisesabove2.465Vatcoldtemperature,
charging is suspended and the internal timer stops. The
CHRG pin output is not affected during this hold state. To
disable the temperature qualification function, ground the
NTC pin.
NC (Pin 10/NA): No Connect.
W
BLOCK DIAGRA
V
CC
CLK:
100µA
I
I
L
SLOP
COMP
DRIVER
–
+
GATE
S
Q
C
R
PWM
25mV or 10mV
R
+
–
+
–
R
SLOP
IL
C
EOC
R
100mV
SENSE
+
–
+
–
M1
CA
VA
BAT
+
–
M2
4.2V/CELL
2.9V OR 5V
4.62V/CELL
+
–
M3
C
LB
OV
RQ
90µA
+
–
C
C
UVLO
4.2V
+
–
+
–
UV EOC
C
SD
RQ
SD
360mV
4.05V/CELL
LOGIC
CHRG
C/10
Q4
+
–
2.465V
V
CC
STOP
TEMP
C
Q5
COLD
NTC_DISABLE
85µA
NTC
25µA
–
+
C
HOT
GND
355mV
50mV
4002 BD
+
–
4002f
9
LTC4002
TEST CIRCUITS
Test Circuit 1
Test Circuit 2
15V
15V
–
–
1.5V
1.5V
LT1006
LT1006
+
+
0V
0V
SENSE
BAT
LTC4002
100µA
–
SENSE
BAT
100µA
COMP
–
+
R
SENSE
COMP
CA
VA
10Ω
R
SENSE
+
CA
10Ω
1mA
V
BAT
–
+
4002 TC01
4.2V
LTC4002
4002 TC02
U
OPERATIO
The LTC4002 is a constant current, constant voltage
Li-Ion battery charger controller that uses a current mode
PWMstep-down(buck)switchingarchitecture.Thecharge
charge mode. In constant current mode, the charge cur-
rent is set by the external sense resistor RSENSE and an
internal 100mV reference; IBAT = 100mV/RSENSE
.
current is set by an external sense resistor (RSENSE
)
When the battery voltage approaches the programmed
float voltage, the charge current will start to decrease.
When the current drops to 25% (4.2 version) or 10% (8.4
version) of the full-scale charge current, an internal com-
paratorturnsofftheinternalpull-downN-channelMOSFET
at the CHRG pin, and connects a weak current source to
ground to indicate a near end-of-charge condition.
across the SENSE and BAT pins. The final battery float
voltage is internally set to 4.2V per cell. For batteries like
lithium-ion that require accurate final float voltage, the
internal 2.465V reference, voltage amplifier and the resis-
tor divider provide regulation with ±1% accuracy.
AchargecyclebeginswhenthevoltageattheVCC pinrises
above the UVLO level and is 250mV or more greater than
the battery voltage. At the beginning of the charge cycle,
if the battery voltage is less than the trickle charge thresh-
old, 2.9V for the 4.2 version and 5V for the 8.4 version, the
charger goes into trickle charge mode. The trickle charge
current is internally set to 10% of the full-scale current. If
the battery voltage stays low for 30 minutes, the battery
is considered faulty and the charge cycle is terminated.
Aninternal3hourtimerdeterminesthetotalchargetime.
After a time out occurs, the charge cycle is terminated
and the CHRG pin is forced high impedance. To restart
the charge cycle, remove and reapply the input voltage or
momentarily shut the charger down. Also, a new charge
cycle will begin if the battery voltage drops below the
recharge threshold voltage of 4.05V per cell.
When the input voltage is present, the charger can be shut
down (ICC = 3mA) by pulling the COMP pin low. When the
input voltage is not present, the charger goes into sleep
Whenthebatteryvoltageexceedsthetricklechargethresh-
old, the charger goes into the full-scale constant current
4002f
10
LTC4002
U
OPERATIO
temperature qualification. The charge cycle is suspended
when the temperature is outside of the 0°C to 50°C
window (with DALE NTHS-1206N02).
mode, dropping ICC to 10µA. This will greatly reduce the
currentdrainonthebatteryandincreasethestandbytime.
A10kΩNTC(negativetemperaturecoefficient)thermistor
can be connected from the NTC pin to ground for battery
W U U
U
APPLICATIO S I FOR ATIO
Undervoltage Lockout (UVLO)
CHRG Status Output Pin
Anundervoltagelockoutcircuitmonitorstheinputvoltage
and keeps the charger off until VCC rises above the UVLO
threshold (4.2V for the 4.2 version, 7.5V for the 8.4
version) and at least 250mV above the battery voltage. To
preventoscillationaroundthethresholdvoltage,theUVLO
circuit has 200mV per cell of built-in hysteresis. When
specifying minimum input voltage requirements, the volt-
age drop across the input blocking diode must be added
to the minimum VCC supply voltage specification.
When a charge cycle starts, the CHRG pin is pulled to
groundbyaninternalN-channelMOSFETwhichiscapable
of driving an LED. When the charge current drops below
the End-of-Charge threshold for more than 120µs, the
N-channel MOSFET turns off and a weak 25µA current
source to ground is connected to the CHRG pin. This weak
25µA pull-down remains until the timer ends the charge
cycle,orthechargerisinmanualshutdownorsleepmode.
After a time out occurs (charge cycle ends), the pin will
become high impedance. By using two different value re-
sistors,amicroprocessorcandetectthreestatesfromthis
pin (charging, end-of-charge and charging stopped) see
Figure 1.
Trickle Charge and Defective Battery Detection
At the beginning of a charge cycle, if the battery voltage is
below the trickle charge threshold, the charger goes into
trickle charge mode with the charge current reduced to
10% of the full-scale current. If the low-battery voltage
persists for 30 minutes, the battery is considered defec-
tive, the charge cycle is terminated and the CHRG pin is
forced high impedance.
V
V
DD
CC
390k
2k
LTC4002
CHRG
µPROCESSOR
OUT
IN
Shutdown
4002 F02
The LTC4002 can be shut down by pulling the COMP pin
to ground which pulls the GATE pin high turning off the
external P-channel MOSFET. When the COMP pin is re-
leased, the internal timer is reset and a new charge cycle
starts. In shutdown, the output of the CHRG pin is high
impedance and the quiescent current remains at 3mA.
Figure 1. Microprocessor Interface
To detect the charge mode, force the digital output pin,
OUT, high and measure the voltage at the CHRG pin. The
N-channel MOSFET will pull the pin low even with a 2k
pull-up resistor. Once the charge current drops below the
End-of-Chargethreshold,theN-channelMOSFETisturned
off and a 25µA current source is connected to the CHRG
pin. The IN pin will then be pulled high by the 2k resistor
connected to OUT. Now force the OUT pin into a high
Removing the input power supply will put the charger
into sleep mode. If the voltage at the VCC pin drops below
(VBAT + 250mV) or below the UVLO level, the LTC4002
goesintoalowcurrent(ICC=10µA)sleepmode,reducing
the battery drain current.
4002f
11
LTC4002
W U U
U
APPLICATIO S I FOR ATIO
impedance state, the current source will pull the pin low
through the 390k resistor. When the internal timer has
expired, the CHRG pin changes to a high impedance state
and the 390k resistor will then pull the pin high to indicate
charging has stopped.
COMP pin at 1.3V. With a 0.47µF capacitor, time to reach
full charge current is about 2.35ms. Capacitance can be
increased up to 1µF if a longer start-up time is needed.
Automatic Battery Recharge
After the 3 hour charge cycle is completed and both the
battery and the input power supply (wall adapter) are still
connected, a new charge cycle will begin if the battery
voltage drops below 4.05V per cell due to self-discharge
or external loading. This will keep the battery capacity at
morethan80%atalltimeswithoutmanuallyrestartingthe
charge cycle.
Gate Drive
The LTC4002 gate driver can provide high transient cur-
rents to drive the external pass transistor. The rise and fall
times are typically 20ns and 50ns respectively when
driving a 2000pF load, which is typical for a P-channel
MOSFET with RDS(ON) in the range of 50mΩ.
Avoltageclampisaddedtolimitthegatedriveto8Vbelow
VCC. For example, if VCC is 10V then the GATE output will
pull down to 2V max. This allows low voltage P-channel
MOSFETs with superior RDS(ON) to be used as the pass
transistor thus increasing efficiency.
Battery Temperature Detection
A negative temperature coefficient (NTC) thermistor
located close to the battery pack can be used to monitor
batterytemperatureandwillnotallowchargingunlessthe
battery temperature is within an acceptable range.
Stability
Connect a 10kΩ thermistor (DALE NTHS-1206N02) from
theNTCpintoground.Ifthetemperaturerisesto50°C,the
resistance of the NTC will be approximately 4.1kΩ. With
the 85µA pull-up current source, the Hot temperature
voltage threshold is 350mV. For Cold temperature, the
voltage threshold is set at 2.465V which is equal to 0°C
(RNTC ≅ 28.4kΩ) with 85µA of pull-up current. If the
temperature is outside the window, the GATE pin will be
pulled up to VCC and the timer frozen while the output
statusattheCHRGpinremainsthesame.Thechargecycle
begins or resumes once the temperature is within the
acceptable range. Short the NTC pin to ground to disable
the temperature qualification feature.
Both the current loop and the voltage loop share a com-
mon, high impedance, compensation node (COMP pin). A
seriescapacitorandresistoronthispincompensatesboth
loops. The resistor is included to provide a zero in the loop
response and boost the phase margin.
The compensation capacitor also provides a soft-start
function for the charger. Upon start-up, the COMP pin
voltage will quickly rise to 0.22V, due to the 2.2k series
resistor, then ramp at a rate set by the internal 100µA pull-
up current source and the external capacitor. Battery
charge current starts ramping up when the COMP pin
voltage reaches 0.8V and full current is achieved with the
4002f
12
LTC4002
W U U
APPLICATIO S I FOR ATIO
U
Input and Output Capacitors
Switchingripplecurrentsplitsbetweenthebatteryandthe
output capacitor depending on the ESR of the output ca-
pacitor and the battery impedance. EMI considerations
usually make it desirable to minimize ripple current in the
battery leads. Ferrite beads or an inductor may be added
to increase battery impedance at the 500kHz switching
frequency. If the ESR of the output capacitor is 0.2Ω and
thebatteryimpedanceisraisedto4Ωwithabeadorinduc-
tor, only 5% of the current ripple will flow in the battery.
Since the input capacitor is assumed to absorb all input
switching ripple current in the converter, it must have an
adequateripplecurrentrating.Worst-caseRMSripplecur-
rent is approximately one-half of output charge current.
Actual capacitance value is not critical. Solid tantalum
capacitors have a high ripple current rating in a relatively
small surface mount package, but caution must be used
when tantalum capacitors are used for input bypass. High
input surge currents can be created when the adapter is
hot-plugged to the charger and solid tantalum capacitors
have a known failure mechanism when subjected to very
high turn-on surge currents. Selecting the highest pos-
sible voltage rating on the capacitor will minimize prob-
lems. Consult with the manufacturer before use.
Design Example
As a design example, take a charger with the following
specifications: VIN = 5V to 22V, VBAT = 4V nominal, IBAT
1.5A, fOSC = 500kHz, see Figure 2.
=
First, calculate the SENSE resistor :
The selection of output capacitor COUT is primarily deter-
mined by the ESR required to minimize ripple voltage and
load step transients. The output ripple ∆VOUT is approxi-
mately bounded by:
RSENSE = 100mV/1.5A = 68mΩ
Choose the inductor for about 65% ripple current at the
maximum VIN:
4V
4V
22V
⎛
⎜
⎝
⎞
⎟
⎠
L =
1–
= 6.713µH
⎛
1
⎞
500kHz 0.65 1.5A
∆VOUT ≤ ∆I ESR +
(
)(
)(
)
⎜
⎟
L
⎝
8fOSCCOUT
⎠
Selecting a standard value of 6.8µH results in a maximum
Since ∆IL increases with input voltage, the output ripple is
highestatmaximuminputvoltage.Typically,oncetheESR
requirement is satisfied, the capacitance is adequate for
filtering and has the necessary RMS current rating.
ripple current of :
4V
500kHz 6.8µH
4V
22V
⎛
⎜
⎝
⎞
⎟
⎠
∆IL =
1–
= 962.6mA
(
)(
)
4002f
13
LTC4002
W U U
U
APPLICATIO S I FOR ATIO
Next, choose the P-channel MOSFET. The Si6435ADQ in
a TSSOP-8 package with RDS(ON) = 42mΩ (nom), 55mΩ
(max) offers a small solution. The maximum power dissi-
pation with VIN = 5V and VBAT = 4V at 50°C ambient
temperature is:
Board Layout Suggestions
When laying out the printed circuit board, the following
considerations should be taken to ensure proper opera-
tion of the LTC4002.
GATEpinriseandfalltimesare20nsand50nsrespectively
(with CGATE = 2000pF). To minimize radiation, the catch
diode, pass transistor and the input bypass capacitor
traces should be kept as short as possible. The positive
side of the input capacitor should be close to the source of
the P-channel MOSFET; it provides the AC current to the
pass transistor. The connection between the catch diode
and the pass transistor should also be kept as short as
possible. The SENSE and BAT pins should be connected
directly to the sense resistor (Kelvin sensing) for best
charge current accuracy. Avoid routing the NTC PC board
traceneartheMOSFETswitchtominimizecouplingswitch-
ing noise into the NTC pin.
2
1.5A 55mΩ 4V
(
) (
)(
)
PD =
= 0.099W
5V
TJ = 50°C + (0.099W)(65°C/W) = 56.5°C
CIN is chosen for an RMS current rating of about 0.8A at
85°C. The output capacitor is chosen for an ESR similar to
thebatteryimpedanceofabout100mΩ.Theripplevoltage
on the BAT pin is:
∆IL(MAX) ESR
(
)
VOUT(RIPPLE)
=
=
2
0.96A 0.1Ω
(
)(
)
= 48mV
2
The compensation capacitor connected at the COMP pin
should return to the ground pin of the IC or as close to it
as possible. This will prevent ground noise from disrupt-
ing the loop stability. The ground pin also works as a heat
sink, therefore use a generous amount of copper around
the ground pin. This is especially important for high VCC
and/or high gate capacitance applications.
C1: Taiyo Yuden TMK325BJ106MM
C2: Taiyo Yuden JMK325BJ226MM
L1: TOKO B952AS-6R8N
TheSchottkydiodeD2showninFigure2conductscurrent
whenthepasstransistorisoff.Inalowdutycyclecase,the
current rating should be the same or higher than the
chargecurrent.Alsoitshouldwithstandreversevoltageas
high as VIN.
V
IN
5V TO 22V
D1
B330
2
C3
C1
10µF
CER
V
0.1µF
CC
BAT
CER
3
M1
GATE
Si6435ADQ
R1
2k
D2
B330
LTC4002ES8-4.2
L1
6.8µH
CHARGE
STATUS
5
1
7
6
CHRG
SENSE
R
SENSE
68mΩ
COMP
NTC
BAT
GND
C
C
4.2V
Li-Ion
BATTERY
4002 F02
+
C2
22µF
CER
0.47µF
8
4
R
C
2.2k
10k
NTC
T
NTC: DALE NTHS-1206N02
Figure 2. 1.5A Single Cell Li-Ion Battery Charger
4002f
14
LTC4002
U
PACKAGE DESCRIPTIO
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699)
R = 0.115
0.38 ± 0.10
TYP
6
10
0.675 ±0.05
3.50 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
PACKAGE
OUTLINE
(DD10) DFN 1103
5
1
0.25 ± 0.05
0.50 BSC
0.75 ±0.05
0.200 REF
0.25 ± 0.05
0.50
BSC
2.38 ±0.10
(2 SIDES)
2.38 ±0.05
(2 SIDES)
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
7
5
8
6
.245
MIN
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
3
4
2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
4002f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC4002
U
TYPICAL APPLICATIO
2-Cell 8.4V, 2A Li-Ion Battery Charger
V
IN
9V TO 12V
R1
100k
M2
1/2 Si9933ADY
C1
10µF
CER
2
C3
V
0.1µF
CC
3
M1
CER
GATE
1/2 Si9933ADY
D2
B330
LTC4002ES8-8.4
L1
6.8µH
7
6
5
CHRG
SENSE
R
SENSE
50mΩ
1
COMP
BAT
C2
22µF
CER
+
8.4V
NTC
8
GND
4
C
C
Li-Ion
0.47µF
BATTERY
R
C
2.2k
10k
T
4002 TA03
NTC
NTC: DALE NTHS-1206N02
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1732-8.4
2-Cell Li-Ion Linear Battery Charger
8.8V ≤ V ≤ 12V; Programmable Charge Termination Timer
Standalone Charger
IN
LTC1733
Li-Ion Battery Charger with Termal Regulation
Standalone Charger, Constant-Current/Constant-Voltage/
Constant-Temperature, Integrated MOSFET, No External Sense
Resistor or Blocking Diodes
LTC1734/LTC1734L SOT-23 Li-Ion Battery Chargers
Need Only Two External Components, Monitors Charge Current, No
Reverse Diode or Sense Resistor Required, 50mA to 700mA
LTC1980
Combination Battery Charger and DC/DC Converter
Wall Adapter May Be Above or Below Battery Voltage, Standalone,
1-, 2-Cell Li-Ion, Also for Charging NiMH and NiCd Batteries
LTC4006/LTC4007
LTC4008
4A Multiple Cell Li-Ion, NiCd, NiMH, Lead Acid
Battery Chargers
6V ≤ V ≤ 28V, High Efficiency ≥90%, V
Digital Interface I/O, Small Inductor
≤ 28V,
IN
OUT
LTC4052/LTC1730
Integrated Pulse Chargers for a 1-Cell Li-Ion Battery
0.35Ω Internal N-FET Requires No Blocking Diode,
Current Limit for Safety
LTC4053
USB Compatible Li-Ion Linear Battery Charger
Charges from USB Input or AC/DC, 100mA/500mA Up to 1.25A,
Thermal Regulation, Fully Integrated
LTC4054
Standalone Linear Li-Ion Battery Charger
with Integrated Pass Transistor in ThinSOTTM
Thermal Regulation Prevents Overheating, C/10 Termination,
C/10 Indicator
LTC4056
Standalone SOT-23 Li-Ion Linear Battery Charger
Low Loss PowerPathTM Controllers in ThinSOT
Charge Termination Included, I ≤ 700mA, 8-Lead ThinSOT Package
CH
LTC4412/LTC4413
Automatic Switching Between DC Sources, Simplified Load Sharing
PowerPath and ThinSOT are trademarks of Linear Technology Corporation.
4002f
LT/TP 1104 1K PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
©LINEAR TECHNOLOGY CORPORATION 2003
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