LTC4054X-4.2 [Linear]
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT; 独立线性锂离子电池充电器采用ThinSOT封装的热调节型号: | LTC4054X-4.2 |
厂家: | Linear |
描述: | Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT |
文件: | 总16页 (文件大小:188K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC4054-4.2/LTC4054X-4.2
Standalone Linear
Li-Ion Battery Charger with
Thermal Regulation in ThinSOT
U
FEATURES
DESCRIPTIO
■
Programmable Charge Current Up to 800mA
The LTC®4054 is a complete constant-current/constant-
voltage linear charger for single cell lithium-ion batteries.
Its ThinSOT package and low external component count
make the LTC4054 ideally suited for portable applications.
Furthermore, theLTC4054isspecificallydesignedtowork
within USB power specifications.
■
No MOSFET, Sense Resistor or Blocking
Diode Required
Complete Linear Charger in ThinSOTTM Package for
Single Cell Lithium-Ion Batteries
Constant-Current/Constant-Voltage Operation with
Thermal Regulation* to Maximize Charge Rate
Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly
from USB Port
■
■
■
No external sense resistor is needed, and no blocking
diode is required due to the internal MOSFET architecture.
Thermal feedback regulates the charge current to limit the
die temperature during high power operation or high
ambient temperature. The charge voltage is fixed at 4.2V,
andthechargecurrentcanbeprogrammedexternallywith
a single resistor. The LTC4054 automatically terminates
the charge cycle when the charge current drops to 1/10th
the programmed value after the final float voltage is
reached.
■
■
Preset 4.2V Charge Voltage with ±1% Accuracy
Charge Current Monitor Output for Gas
Gauging*
■
■
■
■
■
■
■
■
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25µA Supply Current in Shutdown
2.9V Trickle Charge Threshold (LTC4054)
Available Without Trickle Charge (LTC4054X)
Soft-Start Limits Inrush Current
Available in 5-Lead SOT-23 Package
U
When the input supply (wall adapter or USB supply) is
removed, the LTC4054 automatically enters a low current
state, dropping the battery drain current to less than 2µA.
The LTC4054 can be put into shutdown mode, reducing
the supply current to 25µA.
Otherfeaturesincludechargecurrentmonitor,undervoltage
lockout, automatic recharge and a status pin to indicate
charge termination and the presence of an input voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
*U.S.Patent No. 6,522,118
APPLICATIO S
■
Cellular Telephones, PDAs, MP3 Players
Charging Docks and Cradles
■
■
Bluetooth Applications
U
Complete Charge Cycle (750mAh Battery)
TYPICAL APPLICATIO
700
600
500
400
300
200
100
0
4.75
4.50
4.25
4.00
3.75
3.50
3.25
3.00
CONSTANT
CURRENT
600mA Single Cell Li-Ion Charger
CONSTANT
POWER
CONSTANT
VOLTAGE
V
IN
4.5V TO 6.5V
1µF
4
V
3
5
CC
BAT
600mA
LTC4054-4.2
V
= 5V
CC
JA
4.2V
Li-Ion
BATTERY
PROG
θ
= 130°C/W
CHARGE
TERMINATED
GND
2
R
= 1.65k
PROG
= 25°C
1.65k
T
A
0
0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0
TIME (HOURS)
405442 TA01a
405442 TAO1b
405442xf
1
LTC4054-4.2/LTC4054X-4.2
W W U W
ABSOLUTE AXI U RATI GS
(Note 1)
U W
U
PACKAGE/ORDER I FOR ATIO
Input Supply Voltage (VCC) ....................... –0.3V to 10V
PROG............................................. –0.3V to VCC + 0.3V
BAT.............................................................. –0.3V to 7V
CHRG........................................................ –0.3V to 10V
BAT Short-Circuit Duration .......................... Continuous
BAT Pin Current ................................................. 800mA
PROG Pin Current................................................ 800µA
Maximum Junction Temperature .......................... 125°C
Operating Ambient Temperature Range
ORDER PART
TOP VIEW
NUMBER
CHRG 1
GND 2
BAT 3
5 PROG
LTC4054ES5-4.2
LTC4054XES5-4.2
4 V
CC
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
S5 PART MARKING
TJMAX = 125°C, (θJA = 80°C/ W TO
150°C/W DEPENDING ON PC BOARD LAYOUT)
(N0TE 3)
LTH7
LTADY
(Note 2) .............................................. –40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Supply Voltage
Input Supply Current
●
4.25
6.5
V
CC
I
Charge Mode (Note 4), R
Standby Mode (Charge Terminated)
= 10k
●
●
●
300
200
25
2000
500
50
µA
µA
µA
CC
PROG
Shutdown Mode (R
Not Connected,
< V , or V < V )
BAT CC UV
PROG
V
CC
V
Regulated Output (Float) Voltage
BAT Pin Current
0°C ≤ T ≤ 85°C, I = 40mA
BAT
4.158
4.2
4.242
V
FLOAT
A
I
R
R
= 10k, Current Mode
= 2k, Current Mode
●
●
●
93
465
0
100
500
–2.5
±1
107
535
–6
±2
±2
mA
mA
µA
µA
µA
BAT
PROG
PROG
Standby Mode, V
= 4.2V
BAT
Shutdown Mode (R
Not Connected)
< V , R = 2k (Note 5)
TRIKL PROG
PROG
Sleep Mode, V = 0V
±1
CC
I
Trickle Charge Current
V
●
20
2.8
60
45
2.9
80
70
3.0
mA
V
TRIKL
BAT
V
V
V
V
V
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
R
PROG
R
PROG
= 10k, V
Rising (Note 5)
TRIKL
TRHYS
UV
BAT
= 10k (Note 5)
110
3.92
300
mV
V
V
V
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
From V Low to High
●
●
3.7
150
3.8
200
CC
CC
CC
mV
UVHYS
MSD
Manual Shutdown Threshold Voltage
PROG Pin Rising
PROG Pin Falling
●
●
1.15
0.9
1.21
1.0
1.30
1.1
V
V
V
V
– V Lockout Threshold Voltage
V
V
from Low to High
from High to Low
70
5
100
30
140
50
mV
mV
ASD
CC
BAT
CC
CC
I
C/10 Termination Current Threshold
R
PROG
R
PROG
= 10k (Note 6)
= 2k
●
●
0.085
0.085
0.10
0.10
0.115
0.115
mA/mA
mA/mA
TERM
V
PROG Pin Voltage
R
= 10k, Current Mode
●
0.93
8
1.0
20
1.07
35
V
µA
V
PROG
PROG
CHRG
CHRG
I
CHRG Pin Weak Pull-Down Current
CHRG Pin Output Low Voltage
Recharge Battery Threshold Voltage
V
= 5V
CHRG
V
I
= 5mA
0.35
150
0.6
CHRG
∆V
V
- V
RECHRG
100
200
mV
RECHRG
FLOAT
405442xf
2
LTC4054-4.2/LTC4054X-4.2
ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
T
Junction Temperature in Constant
Temperature Mode
120
°C
LIM
R
ON
Power FET “ON” Resistance
600
mΩ
(Between V and BAT)
CC
t
t
t
I
Soft-Start Time
I
= 0 to I
=1000V/R
PROG
100
2
µs
ms
µs
SS
BAT
BAT
Recharge Comparator Filter Time
Termination Comparator Filter Time
PROG Pin Pull-Up Current
V
High to Low
0.75
400
4.5
RECHARGE
TERM
BAT
BAT
I
Falling Below I /10
1000
3
2500
CHG
µA
PROG
Note 4: Supply current includes PROG pin current (approximately 100µA)
but does not include any current delivered to the battery through the BAT
pin (approximately 100mA).
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LTC4054E-4.2 and the LTC4054XE-4.2 are 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.
Note 5: This parameter is not applicable to the LTC4054X.
Note 6: I
is expressed as a fraction of measured full charge current
TERM
with indicated PROG resistor.
Note 3: See Thermal Considerations.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Charge Current vs
PROG Pin Voltage
PROG Pin Voltage vs Supply
Voltage(Constant Current Mode)
PROG Pin Voltage vs
Temperature
1.015
1.010
1.005
1.000
0.995
0.990
0.985
600
500
400
300
200
100
0
1.0100
1.0075
1.0050
1.0025
1.0000
0.9975
0.9950
0.9925
0.9900
V
V
A
R
= 5V
V
V
= 5V
V
= 5V
CC
CC
CC
T = 25°C
A
= 4V
= 4V
BAT
BAT
PROG
T
= 25°C
R
= 10k
R
= 2k
PROG
= 10k
PROG
75
4.0
5.0
5.5
(V)
6.0
6.5
7.0
–50
–25
0
25
50
100
4.5
0
0.25
0.50
V
0.75
(V)
1.00
1.25
TEMPERATURE (°C)
V
CC
PROG
4054 G01
4054 G02
4054 G03
405442xf
3
LTC4054-4.2/LTC4054X-4.2
U W
TYPICAL PERFOR A CE CHARACTERISTICS
PROG Pin Current vs PROG Pin
Voltage (Clamp Current)
PROG Pin Pull-Up Current vs
Temperature and Supply Voltage
PROG Pin Current vs PROG Pin
Voltage (Pull-Up Current)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
3.7
3.5
3.3
3.1
2.9
2.7
2.5
0
–50
V
V
= 4.3V
PROG
BAT
= 0V
V
= 4.2V
CC
–100
–150
–200
–250
–300
–350
–400
V
= 6.5V
CC
V
V
A
= 5V
BAT
= 25°C
V
V
= 5V
BAT
T = 25°C
A
CC
CC
= 4.3V
= 4.3V
T
50
100 125
2.5
3.0 3.5 4.0 4.5
(V)
5.5
–50 –25
0
25
75
2.0
5.0
2.0
2.2
2.3
2.4
2.5
2.6
2.1
V
(V)
TEMPERATURE (°C)
V
PROG
PROG
4054 G05
4054 G04
4054 G06
Regulated Output (Float) Voltage
vs Supply Voltage
Regulated Output (Float) Voltage
vs Charge Current
Regulated Output (Float) Voltage
vs Temperature
4.26
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
4.215
4.210
4.205
4.200
4.195
4.190
4.185
4.215
4.210
4.205
4.200
4.195
4.190
4.185
V
A
R
= 5V
V
= 5V
PROG
T = 25°C
A
CC
= 25°C
CC
T
R
= 10k
R
= 10k
PROG
= 1.25k
PROG
–25
0
25
50
75
100
–50
0
200 300 400 500 600 700
(mA)
4.0
5.0
5.5
(V)
6.0
6.5
7.0
100
4.5
I
V
TEMPERATURE (°C)
BAT
CC
4054 G07
4054 G08
4054 G09
CHRG Pin I-V Curve
(Weak Pull-Down State)
CHRG Pin I-V Curve
(Strong Pull-Down State)
CHRG Pin Current vs Temperature
(Strong Pull-Down State)
25
20
15
10
5
20
18
16
14
12
10
8
22
20
18
16
14
12
10
8
V
V
V
= 5V
= 4V
CHRG
CC
BAT
= 1V
V
V
T
= 5V
= 4V
V
V
T
= 5V
BAT
= 25°C
CC
BAT
CC
6
= 4.3V
= 25°C
A
A
0
4
–50
0
2
3
4
5
6
7
–25
0
25
50
75
100
125
1
4
6
7
0
1
2
3
5
V
(V)
V
(V)
TEMPERATURE (°C)
CHRG
CHRG
4054 G10
4054 G11
4054 G12
405442xf
4
LTC4054-4.2/LTC4054X-4.2
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Current vs
CHRG Pin Current vs Temperature
(Weak Pull-Down State)
Trickle Charge Current
vs Temperature
Supply Voltage
28
25
23
19
16
13
10
50
40
30
20
10
0
50
V
V
V
= 5V
CC
R = 2k
PROG
R
= 2k
= 4.3V
PROG
BAT
CHRG
= 5V
40
30
20
10
0
V
V
= 5V
BAT
V
T
= 2.5V
CC
BAT
= 25°C
= 2.5V
A
R = 10k
PROG
R
= 10k
PROG
25
–50
0
25
50
75
100
–50
0
50
75
100
–25
–25
4.0
4.5
5.0
5.5
(V)
6.0
6.5
7.0
TEMPERATURE (°C)
TEMPERATURE (°C)
V
CC
4054 G13
4054 G14
4054 G15
Trickle Charge Threshold vs
Temperature
Charge Current vs Supply Voltage
Charge Current vs Battery Voltage
600
500
400
300
200
100
0
3.000
2.975
2.950
2.925
2.900
2.875
2.850
2.825
2.800
600
500
400
300
200
100
0
V
= 5V
PROG
CC
R = 2k
PROG
T
= 0°C
R
= 10k
A
T
= 40°C
ONSET OF
A
THERMAL
REGULATION
V
T
JA
= 4V
T
= 25°C
BAT
= 25°C
A
A
θ
= 80°C/W
R
= 10k
PROG
V
= 5V
CC
JA
θ
= 125°C/W
R
= 2k
PROG
4.0
5.0
5.5
6.0
6.5
7.0
–50
0
25
50
75
100
4.2
4.5
–25
2.7
3.0
3.3
3.6
3.9
4.5
TEMPERATURE (°C)
V
(V)
V
(V)
BAT
CC
4054 G18
4054 G16
4054 G17
Power FET “ON” Resistance
vs Temperature
Charge Current vs Ambient
Temperature
Recharge Voltage Threshold
vs Temperature
4.11
4.09
4.07
4.05
4.03
4.01
3.99
600
500
400
300
200
100
0
700
650
600
550
500
450
400
350
V
I
= 4.2V
CC
BAT
R
V
= 5V
PROG
CC
R
= 2k
= 100mA
PROG
R
= 10k
= 2k
PROG
ONSET OF
THERMAL
REGULATION
V
V
θ
= 5V
BAT
= 80°C/W
CC
= 4V
JA
R
= 10k
PROG
50
100 125
50
TEMPERATURE (°C)
100
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–50 –25
0
25
75
–50 –25
0
25
75
TEMPERATURE (°C)
4054 G20
4054 G19
4054 G21
405442xf
5
LTC4054-4.2/LTC4054X-4.2
U
U
U
PI FU CTIO S
PROG (Pin 5): Charge Current Program, Charge Current
Monitor and Shutdown Pin. The charge current is pro-
grammedbyconnectinga1%resistor, RPROG, toground.
When charging in constant-current mode, this pin servos
to 1V. In all modes, the voltage on this pin can be used to
measure the charge current using the following formula:
CHRG (Pin 1): Open-Drain Charge Status Output. When
the battery is charging, the CHRG pin is pulled low by an
internal N-channel MOSFET. When the charge cycle is
completed, a weak pull-down of approximately 20µA is
connected to the CHRG pin, indicating an “AC present”
condition. When the LTC4054 detects an undervoltage
lockout condition, CHRG is forced high impedance.
IBAT = (VPROG/RPROG) • 1000
GND (Pin 2): Ground.
The PROG pin can also be used to shut down the charger.
Disconnecting the program resistor from ground allows
a 3µA current to pull the PROG pin high. When it reaches
the1.21Vshutdownthresholdvoltage, thechargerenters
shutdown mode, charging stops and the input supply
current drops to 25µA. This pin is also clamped to
approximately 2.4V. Driving this pin to voltages beyond
the clamp voltage will draw currents as high as 1.5mA.
Reconnecting RPROG to ground will return the charger to
normal operation.
BAT (Pin 3): Charge Current Output. Provides charge
current to the battery and regulates the final float voltage
to 4.2V. An internal precision resistor divider from this pin
sets the float voltage which is disconnected in shutdown
mode.
VCC (Pin 4): Positive Input Supply Voltage. Provides
power to the charger. VCC can range from 4.25V to 6.5V
and should be bypassed with at least a 1µF capacitor.
WhenVCC dropstowithin30mVoftheBATpinvoltage,the
LTC4054 enters shutdown mode, dropping IBAT to less
than 2µA.
405442xf
6
LTC4054-4.2/LTC4054X-4.2
W
BLOCK DIAGRA
4
V
CC
120°C
1×
T
A
1000×
T
DIE
–
+
BAT
5µA
3
MA
R1
R2
+
–
VA
CA
+
–
–
+
REF
1.21V
SHDN
C1
R3
1V
R4
0.1V
R5
+
–
C2
CHRG
1
STANDBY
3µA
TRICKLE CHARGE
DISABLED ON
LTC4054X
TO
V
+
–
CC
BAT
C3
2.9V
PROG
GND
5
2
405442 BD
R
PROG
405442xf
7
LTC4054-4.2/LTC4054X-4.2
U
OPERATIO
VPROG
RPROG
The LTC4054 is a single cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 800mA of charge current (using a good
thermal PCB layout) with a final float voltage accuracy of
±1%. The LTC4054 includes an internal P-channel power
MOSFET and thermal regulation circuitry. No blocking
diode or external current sense resistor is required; thus,
the basic charger circuit requires only two external com-
ponents. Furthermore, the LTC4054 is capable of operat-
ing from a USB power source.
IBAT
=
•1000
Charge Termination
A charge cycle is terminated when the charge current falls
to1/10ththeprogrammedvalueafterthefinalfloatvoltage
is reached. This condition is detected by using an internal,
filtered comparator to monitor the PROG pin. When the
PROG pin voltage falls below 100mV1 for longer than
tTERM (typically 1ms), charging is terminated. The charge
current is latched off and the LTC4054 enters standby
mode, where the input supply current drops to 200µA.
(Note: C/10 termination is disabled in trickle charging and
thermal limiting modes).
Normal Charge Cycle
AchargecyclebeginswhenthevoltageattheVCC pinrises
abovetheUVLOthresholdlevelanda1%programresistor
is connected from the PROG pin to ground or when a
battery is connected to the charger output. If the BAT pin
is less than 2.9V, the charger enters trickle charge mode.
In this mode, the LTC4054 supplies approximately 1/10
the programmed charge current to bring the battery volt-
age up to a safe level for full current charging. (Note: The
LTC4054X does not include this trickle charge feature).
When charging, transient loads on the BAT pin can cause
thePROGpintofallbelow100mVforshortperiodsoftime
before the DC charge current has dropped to 1/10th the
programmed value. The 1ms filter time (tTERM) on the
termination comparator ensures that transient loads of
this nature do not result in premature charge cycle termi-
nation. Once the average charge current drops below
1/10th the programmed value, the LTC4054 terminates
thechargecycleandceasestoprovideanycurrentthrough
the BAT pin. In this state, all loads on the BAT pin must be
supplied by the battery.
When the BAT pin voltage rises above 2.9V, the charger
enters constant-current mode, where the programmed
charge current is supplied to the battery. When the BAT
pinapproachesthefinalfloatvoltage(4.2V), theLTC4054
enters constant-voltage mode and the charge current
begins to decrease. When the charge current drops to
1/10 of the programmed value, the charge cycle ends.
The LTC4054 constantly monitors the BAT pin voltage in
standby mode. If this voltage drops below the 4.05V
recharge threshold (VRECHRG), another charge cycle be-
gins and current is once again supplied to the battery. To
manuallyrestartachargecyclewheninstandbymode, the
input voltage must be removed and reapplied, or the
charger must be shut down and restarted using the PROG
pin. Figure 1 shows the state diagram of a typical charge
cycle.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The battery charge current
is 1000 times the current out of the PROG pin. The
program resistor and the charge current are calculated
using the following equations:
Charge Status Indicator (CHRG)
1000V
ICHG
1000V
RPROG
RPROG
=
, ICHG =
The charge status output has three different states: strong
pull-down (~10mA), weak pull-down (~20µA) and high
impedance. The strong pull-down state indicates that the
LTC4054 is in a charge cycle. Once the charge cycle has
terminated, the pin state is determined by undervoltage
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage using the
following equation:
Note 1: Any external sources that hold the PROG pin above 100mV will prevent the LTC4054
from terminating a charge cycle.
405442xf
8
LTC4054-4.2/LTC4054X-4.2
U
OPERATIO
lockout conditions. A weak pull-down indicates that VCC
meets the UVLO conditions and the LTC4054 is ready to
charge. High impedance indicates that the LTC4054 is in
undervoltagelockoutmode:eitherVCC is less than 100mV
above theBATpinvoltageorinsufficientvoltageisapplied
to the VCC pin. A microprocessor can be used to distin-
guish between these three states—this method is dis-
cussed in the Applications Information section.
than 2µA and the supply current to less than 50µA. A new
charge cycle can be initiated by reconnecting the program
resistor.
In manual shutdown, the CHRG pin is in a weak pull-down
state as long as VCC is high enough to exceed the UVLO
conditions. The CHRG pin is in a high impedance state if
the LTC4054 is in undervoltage lockout mode: either VCC
iswithin100mVoftheBATpinvoltageorinsufficientvoltage
is applied to the VCC pin.
Thermal Limiting
Aninternalthermalfeedbackloopreducestheprogrammed
charge current if the die temperature attempts to rise
above a preset value of approximately 120°C. This feature
protects the LTC4054 from excessive temperature and
allows the user to push the limits of the power handling
capabilityofagivencircuitboardwithoutriskofdamaging
the LTC4054. The charge current can be set according to
typical (not worst-case) ambient temperature with the
assurance that the charger will automatically reduce the
current in worst-case conditions. ThinSOT power consid-
erationsarediscussedfurtherintheApplicationsInforma-
tion section.
Automatic Recharge
Oncethechargecycleisterminated,theLTC4054continu-
ously monitors the voltage on the BAT pin using a com-
parator with a 2ms filter time (tRECHARGE). A charge cycle
restarts when the battery voltage falls below 4.05V (which
corresponds to approximately 80% to 90% battery capac-
ity). This ensures that the battery is kept at or near a fully
charged condition and eliminates the need for periodic
charge cycle initiations. CHRG output enters astrong pull-
down state during recharge cycles.
POWER ON
BAT < 2.9V
Undervoltage Lockout (UVLO)
TRICKLE CHARGE
MODE
PROG
RECONNECTED
OR
UVLO CONDITION
STOPS
Aninternalundervoltagelockoutcircuitmonitorstheinput
voltageandkeepsthechargerinshutdownmodeuntilVCC
risesabovetheundervoltagelockoutthreshold. TheUVLO
circuit has a built-in hysteresis of 200mV. Furthermore, to
protect against reverse current in the power MOSFET, the
UVLO circuit keeps the charger in shutdown mode if VCC
falls to within 30mV of the battery voltage. If the UVLO
comparator is tripped, the charger will not come out of
shutdown mode until VCC rises 100mV above the battery
voltage.
1/10TH FULL CURRENT
CHRG: STRONG
PULL-DOWN
BAT > 2.9V
BAT > 2.9V
SHUTDOWN MODE
DROPS TO <25µA
CHARGE MODE
I
CC
FULL CURRENT
CHRG: Hi-Z IN UVLO
WEAK PULL-DOWN
OTHERWISE
CHRG: STRONG
PULL-DOWN
PROG < 100mV
STANDBY MODE
NO CHARGE CURRENT
PROG FLOATED
OR
UVLO CONDITION
CHRG: WEAK
PULL-DOWN
Manual Shutdown
2.9V < BAT < 4.05V
At any point in the charge cycle, the LTC4054 can be put
into shutdown mode by removing RPROG thus floating the
PROG pin. This reduces the battery drain current to less
405442 F01
Figure 1. State Diagram of a Typical Charge Cycle
405442xf
9
LTC4054-4.2/LTC4054X-4.2
W U U
U
APPLICATIO S I FOR ATIO
CHARGE
Stability Considerations
10k
CURRENT
MONITOR
CIRCUITRY
PROG
LTC4054
GND
The constant-voltage mode feedback loop is stable with-
out an output capacitor provided a battery is connected to
the charger output. With no battery present, an output
capacitor is recommended to reduce ripple voltage. When
using high value, low ESR ceramic capacitors, it is recom-
mended to add a 1Ω resistor in series with the capacitor.
No series resistor is needed if tantalum capacitors are
used.
R
C
FILTER
PROG
405442 F02
Figure 2. Isolating Capacitive Load on PROG Pin and Filtering
Power Dissipation
The conditions that cause the LTC4054 to reduce charge
current through thermalfeedback can be approximatedby
considering the power dissipated in the IC. Nearly all of
this power dissipation is generated by the internal
MOSFET—this is calculated to be approximately:
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. The constant-current mode stability
is affected by the impedance at the PROG pin. With no
additional capacitance on the PROG pin, the charger is
stable with program resistor values as high as 20k. How-
ever, additional capacitance on this node reduces the
maximum allowed program resistor. The pole frequency
at the PROG pin should be kept above 100kHz. Therefore,
if the PROG pin is loaded with a capacitance, CPROG, the
following equation can be used to calculate the maximum
PD = (VCC – VBAT) • IBAT
where PD is the power dissipated, VCC is the input supply
voltage, VBAT is the battery voltage and IBAT is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
resistance value for RPROG
:
TA = 120°C – PDθJA
1
RPROG
≤
TA = 120°C – (VCC – VBAT) • IBAT • θJA
2π •105 •CPROG
Example: An LTC4054 operating from a 5V USB supply is
programmed to supply 400mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V. Assum-
ingθJA is150°C/W(seeBoardLayoutConsiderations),the
ambient temperature at which the LTC4054 will begin to
reduce the charge current is approximately:
Average, rather than instantaneous, charge current may
beofinteresttotheuser.Forexample,ifaswitchingpower
supply operating in low current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
instantaneous current pulses. In such a case, a simple RC
filter can be used on the PROG pin to measure the average
battery current as shown in Figure 2. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
TA = 120°C – (5V – 3.75V) • (400mA) • 150°C/W
TA = 120°C – 0.5W • 150°C/W = 120°C – 75°C
TA = 45°C
405442xf
10
LTC4054-4.2/LTC4054X-4.2
U
W U U
APPLICATIO S I FOR ATIO
The LTC4054 can be used above 45°C ambient, but the
charge current will be reduced from 400mA. The approxi-
mate current at a given ambient temperature can be
approximated by:
The following table lists thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 3/32" FR-4 board with the device
mounted on topside.
Table 1. Measured Thermal Resistance (2-Layer Board*)
120°C – TA
COPPER AREA
TOPSIDE BACKSIDE
BOARD
AREA
THERMAL RESISTANCE
JUNCTION-TO-AMBIENT
IBAT
=
V
CC – VBAT •θJA
(
)
2
2
2
2
2
2
2
2
2
2
2
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
125°C/W
125°C/W
130°C/W
135°C/W
150°C/W
2
1000mm
Usingthepreviousexamplewithanambient temperature
of 60°C, the charge current will be reduced to approxi-
mately:
2
225mm
100mm
2
2
50mm
*Each layer uses one ounce copper
120°C – 60°C
60°C
187.5°C/A
IBAT
=
=
Table 2. Measured Thermal Resistance (4-Layer Board**)
5V – 3.75V •150°C/W
(
)
COPPER AREA
(EACH SIDE)
BOARD
AREA
THERMAL RESISTANCE
JUNCTION-TO-AMBIENT
IBAT = 320mA
2***
2
2500mm
2500mm
80°C/W
Moreover, when thermal feedback reduces the charge
current, the voltage at the PROG pin is also reduced
proportionally as discussed in the Operation section.
*Top and bottom layers use two ounce copper, inner layers use one ounce copper.
**10,000mm2 total copper area
Increasing Thermal Regulation Current
It is important to remember that LTC4054 applications do
notneedtobedesignedforworst-casethermalconditions
since the IC will automatically reduce power dissipation
when the junction temperature reaches approximately
120°C.
Reducing the voltage drop across the internal MOSFET
can significantly decrease the power dissipation in the IC.
This has the effect of increasing the current delivered to
the battery during thermal regulation. One method is by
dissipatingsomeofthepowerthroughanexternalcompo-
nent, such as a resistor or diode.
Thermal Considerations
Example: An LTC4054 operating from a 5V wall adapter is
programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V. Assum-
ing θJA is 125°C/W, the approximate charge current at an
ambient temperature of 25°C is:
BecauseofthesmallsizeoftheThinSOTpackage, itisvery
important to use a good thermal PC board layout to
maximize the available charge current. The thermal path
for the heat generated by the IC is from the die to the
copper lead frame, through the package leads, (especially
the ground lead) to the PC board copper. The PC board
copper is the heat sink. The footprint copper pads should
be as wide as possible and expand out to larger copper
areas to spread and dissipate the heat to the surrounding
ambient. Feedthrough vias to inner or backside copper
layers are also useful in improving the overall thermal
performance of the charger. Other heat sources on the
board, not related to the charger, must also be considered
when designing a PC board layout because they will affect
overalltemperatureriseandthemaximumchargecurrent.
120°C – 25°C
(5V – 3.75V)•125°C / W
IBAT
=
= 608mA
By dropping voltage across a resistor in series with a 5V
wall adapter (shown in Figure 3), the on-chip power
dissipation can be decreased, thus increasing the ther-
mally regulated charge current
120°C – 25°C
IBAT
=
(VS – IBAT CC – VBAT )•θJA
R
405442xf
11
LTC4054-4.2/LTC4054X-4.2
W U U
U
APPLICATIO S I FOR ATIO
V
S
enough to put the LTC4054 into dropout. Figure 4 shows
how this circuit can result in dropout as RCC becomes
large.
R
CC
ThistechniqueworksbestwhenRCC valuesareminimized
tokeepcomponentsizesmallandavoiddropout. Remem-
ber to choose a resistor with adequate power handling
capability.
V
CC
BAT
LTC4054-4.2
PROG
1µF
Li-Ion
CELL
GND
R
PROG
V
CC Bypass Capacitor
405442 F03
Many types of capacitors can be used for input bypassing,
however, caution must be exercised when using multi-
layerceramiccapacitors.Becauseoftheself-resonantand
high Q characteristics of some types of ceramic capaci-
tors, high voltagetransients can be generated under some
start-up conditions, such as connecting the charger input
to a live power source. Adding a 1.5Ω resistor in series
with an X5R ceramic capacitor will minimize start-up
voltage transients. For more information, refer to Applica-
tion Note 88.
Figure 3. A Circuit to Maximize Thermal Mode Charge Current
Solving for IBAT using the quadratic formula2.
IBAT
=
2 4RCC(120°C – TA)
(VS – VBAT )– (VS – VBAT
2RCC
)
θJA
Using RCC = 0.25Ω, VS = 5V, VBAT = 3.75V, TA = 25°C and
θJA = 125°C/W we can calculate the thermally regulated
charge current to be:
Charge Current Soft-Start
The LTC4054 includes a soft-start circuit to minimize the
inrushcurrentatthestartofachargecycle. Whenacharge
cycleisinitiated,thechargecurrentrampsfromzerotothe
full-scale current over a period of approximately 100µs.
This has the effect of minimizing the transient current load
on the power supply during start-up.
IBAT = 708.4mA
While this application delivers more energy to the battery
and reduces charge time in thermal mode, it may actually
lengthen charge time in voltage mode if VCC becomes low
1000
V
= 5V
CONSTANT
CURRENT
S
800
600
400
200
0
V
= 5.5V
S
DROPOUT
V
= 5.25V
S
THERMAL
MODE
V
= 3.75V
BAT
T
= 25°C
A
JA
θ
= 125°C/W
R
= 1.25kΩ
PROG
0
0.5 0.75 1.0 1.25 1.5 1.75
(Ω)
0.25
R
CC
405442 F04
Figure 4. Charge Current vs RCC
Note 2: Large values of RCC will result in no solution for IBAT. This indicates that the LTC4054
will not generate enough heat to require thermal regulation.
405442xf
12
LTC4054-4.2/LTC4054X-4.2
U
W U U
APPLICATIO S I FOR ATIO
CHRG Status Output Pin
To detect when the LTC4054 is in 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
voltage low even with the 2k pull-up resistor. Once the
charge cycle terminates, the N-channel MOSFET is turned
off and a 20µA current source is connected to the CHRG
pin. The IN pin will then be pulled high by the 2k pull-up
resistor. Todetermineifthereisaweakpull-downcurrent,
the OUT pin should be forced to a high impedance state.
The weak current source will pull the IN pin low through
the 800k resistor; if CHRG is high impedance, the IN pin
will be pulled high, indicating that the part is in a UVLO
state.
The CHRG pin can provide an indication that the input
voltage is greater than the undervoltage lockout threshold
level. A weak pull-down current of approximately 20µA
indicates that sufficient voltage is applied to VCC to begin
charging. When a discharged battery is connected to the
charger, the constant current portion of the charge cycle
begins and the CHRG pin pulls to ground. The CHRG pin
can sink up to 10mA to drive an LED that indicates that a
charge cycle is in progress.
When the battery is nearing full charge, the charger enters
the constant-voltage portion of the charge cycle and the
charge current begins to drop. When the charge current
drops below 1/10 of the programmed current, the charge
cycle ends and the strong pull-down is replaced by the
20µA pull-down, indicating that the charge cycle has
ended. If the input voltage is removed or drops below the
undervoltage lockout threshold, the CHRG pin becomes
high impedance. Figure 5 shows that by using two
different value pull-up resistors, a microprocessor can
detect all three states from this pin.
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity
voltage on VCC is desired. If the supply voltage is high
enough, a series blocking diode can be used. In other
cases, where the voltage drop must be kept low a P-
channel MOSFET can be used (as shown in Figure 6).
+
V
V
DD
DRAIN-BULK
DIODE OF FET
LTC4054
CC
V
V
IN
V
CC
800k
LTC4054
CHRG
µPROCESSOR
4054 F06
2k
OUT
IN
405442 F05
Figure 5. Using a Microprocessor to Determine CHRG State
Figure 6. Low Loss Input Reverse Polarity Protection
405442xf
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.
13
LTC4054-4.2/LTC4054X-4.2
W U U
U
APPLICATIO S I FOR ATIO
USB and Wall Adapter Power
5V WALL
ADAPTER
The LTC4054 allows charging from both a wall adapter
and a USB port. Figure 7 shows an example of how to
combine wall adapter and USB power inputs. A P-channel
MOSFET,MP1,isusedtopreventbackconductingintothe
USB port when a wall adapter is present and a Schottky
diode, D1, is used to prevent USB power loss through the
1k pull-down resistor.
I
CHG
600mA I
LTC4054-4.2
BAT
CHG
3
5
SYSTEM
LOAD
D1
USB POWER
4
V
CC
500mA I
CHG
MP1
+
PROG
10k
Li-Ion
BATTERY
1k
2k
MN1
405442 F07
Typically a wall adapter can supply more current than the
500mA-limitedUSBport.Therefore,anN-channelMOSFET,
MN1, and an extra 10k program resistor are used to
increase the charge current to 600mA when the wall
adapter is present.
Figure 7. Combining Wall Adapter and USB Power
405442xf
14
LTC4054-4.2/LTC4054X-4.2
U
PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
0.62
MAX
0.95
REF
2.90 BSC
(NOTE 4)
1.22 REF
1.50 – 1.75
(NOTE 4)
2.80 BSC
1.4 MIN
3.85 MAX 2.62 REF
PIN ONE
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.09 – 0.20
(NOTE 3)
NOTE:
S5 TSOT-23 0302
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
405442xf
15
LTC4054-4.2/LTC4054X-4.2
U
TYPICAL APPLICATIO S
USB/Wall Adapter Power Li-Ion Charger
Full Featured Single Cell Li-Ion Charger
V
= 5V
I
IN
BAT
5V WALL
ADAPTER
3
BAT
+
LTC4054-4.2
Li-Ion
CELL
1µF
500mA
4
4
USB
POWER
V
CC
2.5k
5
V
3
5
CC
1µF
PROG
GND
BAT
330Ω
100mA/
500mA
LTC4054-4.2
2
1k
10k
1
+
CHRG
PROG
µC
GND
2
2k
405442 TA05
SHDN
800mA Li-Ion Charger with External Power Dissipation
405442 TA02
V
= 5V
IN
Basic Li-Ion Charger with Reverse Polarity Input Protection
0.25Ω
800mA
4
3
5
V
BAT
LTC4054-4.2
CC
500mA
4
3
5
5V WALL
ADAPTER
1µF
V
CC
BAT
LTC4054-4.2
PROG
GND
2
+
+
PROG
1µF
1.25k
GND
2
2k
405442 TA03
405442 TA04
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1732
Lithium-Ion Linear Battery Charger Controller
Simple Charger uses External FET, Features Preset Voltages, C/10
Charger Detection and Programmable Timer, Input Power Good Indication
LTC1733
LTC1734
LTC1734L
LTC1998
LTC4050
Monolithic Lithium-Ion Linear Battery Charger
Lithium-Ion Linear Battery Charger in ThinSOT
Lithium-Ion Linear Battery Charger in ThinSOT
Lithium-Ion Low Battery Detector
Standalone Charger with Programmable Timer, Up to 1.5A Charge Current
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
Low Current Version of LTC1734
1% Accurate 2.5µA Quiescent Current, SOT-23
Lithium-Ion Linear Battery Charger Controller
Simple Charger uses External FET, Features Preset Voltages, C/10
Charger Detection and Programmable Timer, Input Power Good Indication,
Thermistor Interface
LTC4052
LTC4053
LTC4054L
Monolithic Lithium-Ion Battery Pulse Charger
No Blocking Diode or External Power FET Required
USB Compatible Monolithic Li-Ion Battery Charger
Standalone Charger with Programmable Timer, Up to 1.25A Charge Current
10mA to 150mA Standalone Monolithic Lithium-Ion Low Current Version of LTC4054
Linear Battery Charger in ThinSOT
LTC4056
LTC4057
LTC4410
Standalone Lithium-Ion Linear Battery Charger
in ThinSOT
Standalone Charger with Programmable Timer, No Blocking Diode,
No Sense Resistor Needed
Monolithic Lithium-Ion Linear Battery Charger
with Thermal Regulation in ThinSOT
No External MOSFET, Sense Resistor or Blocking Diode Required,
Charge Current Monitor for Gas Gauging
USB Power Manager
For Simultaneous Operation of USB Peripheral and Battery Charging from USB
Port, Keeps Current Drawn from USB Port Constant, Keeps Battery Fresh, Use
with the LTC4053, LTC1733, or LTC4054
405442xf
LT/TP 0903 1K • PRINTED IN USA
16 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
相关型号:
LTC4054XES5-4.2#TRM
LTC4054X-4.2 - Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT; Package: SOT; Pins: 5; Temperature Range: -40°C to 85°C
Linear
LTC4055EUF#PBF
LTC4055/LTC4055-1 - USB Power Controller and Li-Ion Linear Charger; Package: QFN; Pins: 16; Temperature Range: -40°C to 85°C
Linear
LTC4055EUF-1#PBF
LTC4055/LTC4055-1 - USB Power Controller and Li-Ion Linear Charger; Package: QFN; Pins: 16; Temperature Range: -40°C to 85°C
Linear
©2020 ICPDF网 联系我们和版权申明