FEATURES
n
LTC4080
500mA Standalone Li-Ion
Charger with Integrated
300mA Synchronous Buck
DESCRIPTION
The
LTC
®
4080
is a complete constant-current/constant-
voltage linear battery charger for a single-cell 4.2V
lithium-ion battery with an integrated 300mA synchronous
buck converter. The small packages and low external
component count make the LTC4080 especially suitable
for portable applications. Furthermore, LTC4080 is specifi-
cally designed to work within USB power specifications.
The
CHRG
pin indicates when charge current has
dropped to ten percent of its programmed value (C/10).
An internal 4.5-hour timer terminates the charge cycle.
The full-featured LTC4080 battery charger also includes
trickle charge, automatic recharge and soft-start (to limit
inrush current).
The LTC4080 integrates a synchronous buck converter
that is powered from the BAT pin. It has an adjustable
output voltage and can deliver up to 300mA of load cur-
rent. The buck converter also features low current high
efficiency Burst Mode operation that can be selected by
the MODE pin.
The LTC4080 is available in 10-lead, low profile (0.75mm)
3mm × 3mm DFN and MSOP Exposed Pad packages.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT and PowerPath are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
6522118.
Complete Linear Battery Charger with Integrated
Buck Converter
Battery Charger:
n
Constant-Current/Constant-Voltage Operation
with Thermal Feedback to Maximize Charge Rate
without Risk of Overheating
n
Internal 4.5-Hour Safety Timer for Termination
n
Charge Current Programmable Up to 500mA with
5% Accuracy
n
C/10 Charge Current Detection Output
n
5µA Supply Current in Shutdown Mode
Switching Regulator:
n
High Efficiency Synchronous Buck Converter
n
300mA Output Current
n
2.7V to 4.5V Input Range (Powered from BAT Pin)
n
0.8V to V
BAT
Output Range
n
MODE Pin Selects Fixed (2.25MHz) Constant-Frequency
PWM Mode or Low I
CC
(23µA) Burst Mode
®
Operation
n
2µA BAT Current in Shutdown Mode
APPLICATIONS
n
n
n
n
Wireless Headsets
Bluetooth Applications
Portable MP3 Players
Multifunction Wristwatches
TYPICAL APPLICATION
Li-Ion Battery Charger with 1.8V Buck Regulator
500mA
V
CC
(3.75V
to 5.5V)
V
CC
EN_CHRG
LTC4080
C
IN
4.7 F
MODE
FB
GND PROG
R
PROG
806Ω
R2
806k
4080 TA01a
Buck Efficiency vs Load Current
(V
OUT
= 1.8V)
100
EFFICIENCY
(Burst)
EFFICIENCY
(PWM)
1000
BAT
EN_BUCK
SW
L1, 1O H
C
PL
10pF
R1
1M
EFFICIENCY (%)
C
BAT
4.7 F
+
4.2V
Li-Ion
BATTERY
80
100
POWER LOSS (mW)
POWER
LOSS 10
(PWM)
0
60
40
V
OUT
(1.8V/300mA)
C
OUT
4.7 F
POWER LOSS
(Burst)
20
0
0.01
V
BAT
= 3.8V 0.1
V
OUT
= 1.8V
L = 10 H
C = 4.7 F
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
4080 TA01b
4080fc
For more information
www.linear.com/LTC4080
1
LTC4080
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
CC
, t < 1ms and Duty Cycle < 1% ............... –0.3V to 7V
V
CC
Steady State .......................................... –0.3V to 6V
BAT,
CHRG
................................................... –0.3V to 6V
EN_CHRG, PROG,
ACPR
..................–0.3V to V
CC
+ 0.3V
MODE, EN_BUCK ........................... –0.3V to V
BAT
+ 0.3V
FB ................................................................ –0.3V to 2V
BAT Short-Circuit Duration ........................... Continuous
BAT Pin Current .................................................. 800mA
PROG Pin Current ....................................................2mA
Junction Temperature ............................................125°C
Operating Temperature Range (Note 2)....–40°C to 85°C
Storage Temperature Range .................. –65°C to 125°C
Lead Temperature (MSE, Soldering, 10 sec) ......... 300°C
PIN CONFIGURATION
TOP VIEW
BAT
V
CC
EN_CHRG
PROG
ACPR
1
2
3
4
5
11
10 SW
9 EN_BUCK
8 MODE
7 FB
6
CHRG
TOP VIEW
BAT
V
CC
EN_CHRG
PROG
ACPR
1
2
3
4
5
10
9
8
7
6
SW
EN_BUCK
MODE
FB
CHRG
11
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
JMAX
= 110°C,
θ
JA
= 43°C/W (NOTE 3)
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
MSE PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 40°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC4080EDD#PBF
LTC4080EMSE#PBF
TAPE AND REEL
LTC4080EDD#TRPBF
LTC4080EMSE#TRPBF
PART MARKING
LBXD
LTCQH
PACKAGE DESCRIPTION
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
V
BAT
I
CC
I
CC_SD
I
BAT_SD
PARAMETER
Supply Voltage
Input Voltage for the Switching
Regulator
The
l
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C, V
CC
= 5V, V
BAT
= 3.8V, V
EN_CHRG
= 0V, V
EN_BUCK
= V
BAT
, V
MODE
= 0V. (Note 2)
CONDITIONS
(Note 4)
(Note 5)
l
l
l
MIN
3.75
2.7
TYP
5
3.8
110
5
2
0.6
2
MAX
5.5
4.5
300
10
5
UNITS
V
V
µA
µA
µA
µA
µA
4080fc
Quiescent Supply Current (Charger On, V
BAT
= 4.5V (Forces I
BAT
and I
PROG
= 0),
Switching Regulator Off)
V
EN_BUCK
= 0
l
Supply Current in Shutdown (Both Battery V
EN_CHRG
= 5V, V
EN_BUCK
= 0, V
CC
> V
BAT
Charger and Switching Regulator Off)
V
EN_CHRG
= 4V, V
EN_BUCK
= 0, V
CC
(3.5V) < V
BAT
(4V)
Battery Current in Shutdown (Both Battery
Charger and Switching Regulator Off)
l
V
EN_CHRG
= 5V, V
EN_BUCK
= 0, V
CC
> V
BAT
V
EN_CHRG
= 4V, V
EN_BUCK
= 0, V
CC
(3.5V) < V
BAT
(4V)
2
For more information
www.linear.com/LTC4080
LTC4080
ELECTRICAL CHARACTERISTICS
SYMBOL
Battery Charger
V
FLOAT
I
BAT
V
UVLO_CHRG
V
PROG
V
ASD
t
SS_CHRG
I
TRKL
V
TRKL
V
TRHYS
DV
RECHRG
DV
UVCL1,
DV
UVCL2
t
TIMER
V
BAT
Regulated Output Voltage
Current Mode Charge Current
V
CC
Undervoltage Lockout Voltage
PROG Pin Servo Voltage
I
BAT
= 2mA
I
BAT
= 2mA, 4.3V < V
CC
< 5.5V
R
PROG
= 4k; Current Mode; V
EN_BUCK
= 0
R
PROG
= 0.8k; Current Mode; V
EN_BUCK
= 0
V
CC
Rising
V
CC
Falling
0.8k ≤ R
PROG
≤ 4k
l
l
l
l
l
l
The
l
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C, V
CC
= 5V, V
BAT
= 3.8V, V
EN_CHRG
= 0V, V
EN_BUCK
= V
BAT
, V
MODE
= 0V. (Note 2)
PARAMETER
CONDITIONS
MIN
4.179
4.158
90
475
3.5
2.8
0.98
60
15
35
l
TYP
4.2
4.2
100
500
3.6
3.0
1.0
82
32
180
50
2.9
150
100
300
130
4.5
2.25
1.125
0.1
115
MAX
4.221
4.242
110
525
3.7
3.2
1.02
100
45
65
3.05
350
130
UNITS
V
V
mA
mA
V
V
V
mV
mV
µs
mA
V
mV
mV
mV
mV
Automatic Shutdown Threshold Voltage (V
CC
– V
BAT
), V
CC
Low to High
(V
CC
– V
BAT
), V
CC
High to Low
Battery Charger Soft-Start Time
Trickle Charge Current
Trickle Charge Threshold Voltage
Trickle Charge Threshold Voltage
Hysteresis
Recharge Battery Threshold Voltage
(V
CC
– V
BAT
) Undervoltage Current
Limit Threshold Voltage
Termination Timer
Recharge Time
Low-Battery Charge Time
V
BAT
= 2.5V
R
PROG
= 2k (Note 6)
V
FLOAT
– V
BAT
, 0°C < T
A
< 85°C
I
BAT
= 0.9 I
CHG
I
BAT
= 0.1 I
CHG
l
l
l
l
V
BAT
= 2V, R
PROG
= 0.8k
V
BAT
Rising
2.75
100
70
180
90
3
1.5
0.75
0.085
6
3
1.5
0.115
hrs
hrs
hrs
mA/mA
°C
mW
Hz
%
I
C/10
T
LIM
R
ON_CHRG
f
BADBAT
D
BADBAT
Buck Converter
V
FB
I
FB
f
OSC
I
BAT_NL_CF
I
BAT_NL_BM
I
BAT_SLP
V
UVLO_BUCK
R
ON_P
End of Charge Indication Current Level
Junction Temperature in Constant-
Temperature Mode
Power FET On-Resistance (Between
V
CC
and BAT)
I
BAT
= 350mA, V
CC
= 4V
750
2
75
Defective Battery Detection
CHRG
Pulse V
BAT
= 2V
Frequency
Defective Battery Detection
CHRG
Pulse V
BAT
= 2V
Frequency Duty Ratio
FB Servo Voltage
FB Pin Input Current
Switching Frequency
No-Load Battery Current (Continuous
Frequency Mode)
No-Load Battery Current (Burst Mode
Operation)
Battery Current in SLEEP Mode
Buck Undervoltage Lockout
PMOS Switch On-Resistance
No-Load for Regulator, V
EN_CHRG
= 5V,
L = 10µH, C = 4.7µF
No-Load for Regulator, V
EN_CHRG
= 5V,
MODE = V
BAT
, L = 10µH, C = 4.7µF
V
EN_CHRG
= 5V, MODE = V
BAT
,
V
OUT
> Regulation Voltage
V
BAT
Rising
V
BAT
Falling
l
l
l
l
0.78
–50
1.8
0.80
2.25
1.9
23
0.82
50
2.75
V
nA
MHz
mA
µA
V
FB
= 0.85V
l
10
2.6
2.4
15
2.7
2.5
0.95
20
2.8
2.6
µA
V
V
W
4080fc
For more information
www.linear.com/LTC4080
3
LTC4080
ELECTRICAL CHARACTERISTICS
SYMBOL
R
ON_N
I
LIM_P
I
LIM_N
I
ZERO_CF
I
PEAK
I
ZERO_BM
t
SS_BUCK
Logic
V
IH
V
IL
V
OL
I
IH
I
IL
R
EN_CHRG
I
CHRG
I
ACPR
Input High Voltage
Input Low Voltage
Output Low Voltage (CHRG,
ACPR)
Input Current High
Input Current Low
EN_CHRG Pin Input Resistance
CHRG
Pin Leakage Current
ACPR
Pin Leakage Current
EN_CHRG, EN_BUCK, MODE Pin Low to High
EN_CHRG, EN_BUCK, MODE Pin High to Low
I
SINK
= 5mA
EN_BUCK, MODE Pins at 5.5V, V
BAT
= 5V
EN_CHRG, EN_BUCK, MODE Pins at GND
V
EN_CHRG
= 5V
V
BAT
= 4.5V, V
EN_CHRG
= 5V
V
CC
= 3V, V
EN_CHRG
= 5V
l
l
l
l
l
l
l
The
l
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C, V
CC
= 5V, V
BAT
= 3.8V, V
EN_CHRG
= 0V, V
EN_BUCK
= V
BAT
, V
MODE
= 0V. (Note 2)
PARAMETER
NMOS Switch On-Resistance
PMOS Switch Current Limit
NMOS Switch Current Limit
NMOS Zero Current in Normal Mode
Peak Current in Burst Mode Operation
Zero Current in Burst Mode Operation
Buck Soft-Start Time
MODE = V
BAT
MODE = V
BAT
From the Rising Edge of EN_BUCK to 90%
of Buck Regulated Output
50
20
375
CONDITIONS
MIN
TYP
0.85
520
700
15
100
35
400
150
50
700
MAX
UNITS
W
mA
mA
mA
mA
mA
µs
1.2
0.4
60
–1
–1
1
1.7
105
1
1
3.3
1
1
V
V
mV
µA
µA
MW
µA
µA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC4080 is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
43°C/W.
Note 4:
Although the LTC4080 charger functions properly at 3.75V, full
charge current requires an input voltage greater than the desired final
battery voltage per ∆
VUVCL1
specification.
Note 5:
The 2.8V maximum buck undervoltage lockout (V
UVLO_BUCK
) exit
threshold must first be exceeded before the minimum V
BAT
specification
applies.
Note 6:
IC/10 is expressed as a fraction of measured full charge current
with indicated PROG resistor.
4
4080fc
For more information
www.linear.com/LTC4080
LTC4080
TYPICAL PERFORMANCE CHARACTERISTICS
(T
A
= 25°C, V
CC
= 5V, V
BAT
= 3.8V, unless otherwise specified)
Battery Regulation (Float) Voltage
vs Charge Current
R
PROG
= 2k
4.21
4.20
FLOAT VOLTAGE (V)
FLOAT VOLTAGE (V)
4.210
4.205
CHARGE CURRENT (mA)
Battery Regulation (Float) Voltage
vs Temperature
250
Charge Current
vs Battery Voltage
R
PROG
= 2k
V
BAT
RISING
4.19
4.18
4.17
4.16
4.15
4.14
4.13
0
50
200
150
100
CHARGE CURRENT (mA)
250
4080 G01
4.200
4.195
4.190
4.185
4.180
4.175
4.170
4.165
4.160
– 50 – 30
– 10
50
30
10
TEMPERATURE (°C)
70
90
4080 G02
200
150
100
50
TRICKLE CHARGE
0
0
1
3
4
2
BATTERY VOLTAGE (V)
5
4080 G03
4.25
4.20
Battery Regulation (Float) Voltage
vs Supply Voltage
250
Charge Current vs Temperature
with Thermal Regulation
(Constant-Current Mode)
V
CC
= 6V
V
BAT
= 3V
R
PROG
= 2k
1.0
PROG Pin Voltage
vs Charge Current
R
PROG
= 2k
4.05
4.00
3.95
3.90
3.85
4
4.5
5.5
INPUT VOLTAGE (V)
5
6
4080 G04
THERMAL CONTROL
LOOP IN OPERATION
V
PROG
(V)
4.10
CHARGE CURRENT (mA)
4.15
FLOAT VOLTAGE (V)
200
0.8
150
0.6
100
0.4
0.2
50
0
–50
0
–25
0
25
50
75
100
125
4080 G05
0
25
TEMPERATURE (°C)
50 75 100 125 150 175 200
CHARGE CURRENT (mA)
4080 G06
0.9
Charger FET On-Resistance
vs Temperature
0.95
0.90
0.85
VOLTAGE (V)
0.80
0.75
0.70
0.65
0.60
0.55
EN_CHRG, BUCK and
MODE Pin Threshold Voltage
vs Temperature
1.7
EN_CHRG Pin Pull-Down
Resistance vs Temperature
1.6
RESISTANCE (MΩ)
1.5
1.4
1.3
1.2
1.1
V
CC
= 4V
0.8 I
BAT
= 350mA
0.7
0.6
R
DS(ON)
(Ω)
0.5
0.4
0.3
0.2
0.1
0
– 50 – 30
–10
50
30
10
TEMPERATURE (°C)
70
90
4080 G07
RISING
FALLING
0.50
–50
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
4080 G08
1.0
–50
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
4080 G09
4080fc
For more information
www.linear.com/LTC4080
5
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