LTC3440 [Linear Systems]
Standalone 250mA Li-Ion Battery Charger in 2 × 2 DFN; 独立250毫安锂离子电池充电器的2×2 DFN型号: | LTC3440 |
厂家: | Linear Systems |
描述: | Standalone 250mA Li-Ion Battery Charger in 2 × 2 DFN |
文件: | 总18页 (文件大小:183K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC4065L/
LTC4065LX/LTC4065L-4.1
Standalone 250mA Li-Ion
Battery Charger in 2 × 2 DFN
FEATURES
DESCRIPTION
The LTC®4065L is a complete constant-current/constant-
voltage linear charger for single-cell lithium-ion batteries.
Its small size and ability to accurately regulate low charge
currents make the LTC4065L especially well-suited for
portable applications using low capacity rechargeable
lithium-ion cells. Furthermore, LTC4065L is specifically
designed to work within USB power specifications.
n
Charge Current Programmable up to 250mA with
5% Accuracy
n
Complete Linear Charger in 2mm × 2mm DFN Package
n
C/10 Charge Current Detection Output
Timer Termination
n
n
No External MOSFET, Sense Resistor or Blocking
Diode Required
n
Preset Float Voltage with 0.6% Accuracy:
The CHRG pin indicates when charge current has dropped
to ten percent of its programmed value (C/10). An internal
timer terminates charging according to battery manufac-
turer specifications.
4.2V for LTC4065L/LTC4065LX
4.1V for LTC4065L-4.1
Constant-Current/Constant-Voltage Operation with
n
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
TheLTC4065L-4.1featuresaconstant-voltagefloatvoltage
of 4.1V. This 4.1V version of the standard LTC4065L is in-
tendedforback-uporhighambienttemperatureapplications.
Under these conditions, a reduced float voltage will trade-
off initial cell capacity for the benefit of increased capacity
retention over the life of the battery. A reduced float voltage
also minimizes swelling in prismatic and polymer cells.
n
Charge Current Monitor Output for Gas Gauging
n
Automatic Recharge
n
Charges Single Cell Li-Ion Batteries Directly from
USB Port
n
20μA Supply Current in Shutdown Mode
n
Available Without Trickle Charge (LTC4065LX)
n
Tiny 6-Lead (2mm × 2mm) DFN Package
When the input supply (wall adapter or USB supply) is
removed,theLTC4065Lautomaticallyentersalowcurrent
state,droppingbatterydraincurrenttolessthan1μA.With
powerapplied,LTC4065Lcanbeputintoshutdownmode,
reducing the supply current to less than 20μA.
APPLICATIONS
n
Charger for Li-Ion Coin Cell Batteries
n
Portable MP3 Players, Wireless Headsets
n
Bluetooth Applications
Multifunction Wristwatches
The full-featured LTC4065L also includes automatic re-
charge,low-batterychargeconditioning(tricklecharging)
and soft-start (to limit inrush current).
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6522118, 6700364.
Complete Charge Cycle (180mAh Battery)
LTC4065L and LTC4065LX
TYPICAL APPLICATION
110
Standalone Li-Ion Battery Charger
100
90 CONSTANT
CURRENT
4.3
4.1
3.9
3.7
3.5
3.3
100mA
V
IN
CONSTANT
VOLTAGE
V
BAT
LTC4065L
CHRG PROG
EN GND
80
70
60
50
40
30
20
10
0
CC
4.3V TO 5.5V
R1
510Ω
4.2V
C1
1μF
CHRG
TRANSITION
+
Li-Ion
BATTERY
R3
2k
4065L TA01
CHARGE
TERMINATION
V
= 5V
PROG
CC
R
= 2k
0
1
1.5
2
2.5
3
3.5
4
4.5
0.5
TIME (HOURS)
4065 TA02
4065lfb
1
LTC4065L/
LTC4065LX/LTC4065L-4.1
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
V
CC
TOP VIEW
t < 1ms and Duty Cycle < 1% ..................–0.3V to 7V
Steady State............................................. –0.3V to 6V
GND
CHRG
BAT
1
2
3
6
5
4
PROG
7
BAT, CHRG ...................................................–0.3V to 6V
EN, PROG.........................................–0.3V to V + 0.3V
EN
V
CC
CC
BAT Short-Circuit Duration............................Continuous
BAT Pin Current ...................................................275mA
PROG Pin Current.............................................1.342mA
Junction Temperature (Note 6) ............................. 125°C
Operating Temperature Range (Note 2)....–40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
T
= 125°C, θ = 60°C/W (NOTE 3)
JA
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
JMAX
ORDER INFORMATION
LEAD FREE FINISH
LTC4065LEDC#PBF
LTC4065LXEDC#PBF
TAPE AND REEL
PART MARKING
LCBD
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4065LEDC#TRPBF
LTC4065LXEDC#TRPBF
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
6-Lead (2mm × 2mm) Plastic DFN
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
LCKS
LTC4065LEDC-4.1#PBF LTC4065LEDC-4.1#TRPBF LGGN
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/
LTC4065 Options
PART NUMBER
LTC4065
FLOAT VOLTAGE
CHARGE CURRENT RANGE PIN 5 IS EN OR ACPR?
TRICKLE CHARGE?
4.2V
4.2V
4.4V
4.2V
4.2V
4.1V
40mA TO 750mA
40mA TO 750mA
40mA TO 750mA
8mA TO 250mA
8mA TO 250mA
8mA TO 250mA
EN
YES
YES
YES
YES
NO
LTC4065A
ACPR
EN
LTC4065-4.4
LTC4065L
EN
LTC4065LX
LTC4065L-4.1
EN
EN
YES
4065lfb
2
LTC4065L/
LTC4065LX/LTC4065L-4.1
ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VCC = 5V, VBAT = 3.8V, VEN = 0V unless otherwise specified. (Note 2)
SYMBOL PARAMETER
Supply Voltage
CONDITIONS
MIN
TYP
MAX
5.5
250
40
UNITS
V
l
l
l
l
V
V
(Note 4)
3.75
CC
CC
I
I
I
Quiescent V Supply Current
V
V
V
= 4.5V (Forces I and I = 0)
PROG
120
20
6
μA
CC
CC
BAT
BAT
V
Supply Current in Shutdown
= 5V
μA
CCMS
CCUV
CC
EN
V
Supply Current in Undervoltage
< V , V = 3.5V, V = 4V
11
μA
CC
CC
BAT CC
BAT
Lockout
V
V
Regulated Output Voltage
I
I
I
I
= 2mA
= 2mA, 0°C < T < 85°C
= 2mA (LTC4065L-4.1)
= 2mA, 0°C < T < 85°C (LTC4065L-4.1)
4.175
4.158
4.075
4.058
4.2
4.2
4.1
4.1
4.225
4.242
4.125
4.142
V
V
V
V
FLOAT
BAT
BAT
BAT
BAT
BAT
A
A
l
l
I
I
I
BAT Pin Current
R
R
= 13.3k (0.1%), Current Mode
= 1.33k (0.1%), Current Mode
13.5
148
15.5
155
17.5
162
mA
mA
BAT
PROG
PROG
l
Battery Drain Current in Shutdown
Mode
V
= V
CC
–1
0
1
μA
BMS
BUV
EN
l
Battery Drain Current in Undervoltage
Lockout
V
= 3.5V, V = 4V
0
1
4
μA
CC
BAT
l
l
V
UVLO
V
PROG
V
ASD
V
Undervoltage Lockout Voltage
V
V
Rising
Falling
3.4
2.8
3.6
3.0
3.8
3.2
V
V
CC
CC
CC
l
l
PROG Pin Voltage
R
R
= 1.33k, I
= 13.3k, I
= 0.75mA
= 75μA
0.98
0.98
1
1
1.02
1.02
V
V
PROG
PROG
PROG
PROG
Automatic Shutdown Threshold Voltage (V – V ), V Low to High
60
15
80
30
100
45
mV
mV
CC
BAT
CC
(V – V ), V High to Low
CC
BAT
CC
V
V
Manual Shutdown High Voltage
Manual Shutdown Low Voltage
EN Pin Input Resistance
V
V
Rising
1
V
V
MSH
EN
EN
Falling
0.6
0.9
MSL
l
l
R
1.5
170
15.5
2.9
3.3
MΩ
μs
EN
t
I
Soft-Start Time
SS
TRKL
Trickle Charge Current
V
V
= 2V, R
= 1.33k (0.1%) (Note 7)
13
18
mA
V
BAT
BAT
PROG
V
V
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
Recharge Battery Threshold Voltage
Rising (Note 7)
2.7
3.05
TRKL
(Note 7)
– V
90
mV
mV
TRHYS
ΔV
V
, 0°C < T < 85°C
70
100
130
RECHRG
FLOAT
RECHRG
A
ΔV
UVCL1
ΔV
UVCL2
(V – V ) Undervoltage Current
Limit
I
= 90%, R
= 10%, R
= 2k, Programmed Charge Current
= 2k, Programmed Charge Current
150
80
190
125
300
150
mV
mV
CC
BAT
BAT
PROG
PROG
I
BAT
l
l
l
l
t
Termination Timer
3
4.5
2.25
1.125
60
6
3
Hrs
Hrs
Hrs
mV
TIMER
Recharge Time
1.5
Low-Battery Trickle Charge Time
CHRG Pin Output Low Voltage
V
= 2.5V
0.75
1.5
105
BAT
V
I
= 5mA
CHRG
CHRG
4065lfb
3
LTC4065L/
LTC4065LX/LTC4065L-4.1
ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VCC = 5V, VBAT = 3.8V, VEN = 0V unless otherwise specified. (Note 2)
SYMBOL PARAMETER
CONDITIONS
= 4.5V, V
MIN
TYP
0
MAX
1
UNITS
μA
l
l
I
I
CHRG Pin Input Current
V
= 5V
CHRG
CHRG
BAT
End of Charge Indication Current Level
R
= 1.33k (Note 5)
PROG
0.08
0.095
115
0.11
mA/mA
°C
C/10
T
LIM
Junction Temperature in Constant
Temperature Mode
R
Power FET “ON” Resistance
I
= 150mA
1.5
2
Ω
Hz
%
ON
BAT
(Between V and BAT)
CC
f
Defective Battery Detection CHRG
Pulse Frequency
BADBAT
D
Defective Battery Detection CHRG
75
BADBAT
Pulse Frequency Duty Ratio
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 4: Although the LTC4065L functions properly at 3.75V input, full
charge current requires an input voltage greater than the desired final bat-
tery voltage per the ΔV
specification.
UVCL1
Note 5: I
is expressed as a fraction of measured full charge current
C/10
Note 2: The LTC4065L is tested under pulsed load conditions such that
with indicated PROG resistor.
T ≈ T . The LTC4065L is guaranteed to meet performance specifica-
J
A
Note 6: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
tions 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 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
rated.
Note 7: This parameter is not applicable to the LTC4065LX.
4065lfb
4
LTC4065L/
LTC4065LX/LTC4065L-4.1
TYPICAL PERFORMANCE CHARACTERISTICS
Battery Regulation (Float) Voltage
vs Battery Charge Current
Battery Regulation (Float) Voltage
vs Temperature
Battery Regulation (Float) Voltage
vs Supply Voltage
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
4.08
4.06
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
4.08
4.06
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
4.08
4.06
V
A
R
= 5V
CC
T
I
= 25°C
= 2mA
PROG
A
BAT
R
T
= 25°C
= 800Ω
PROG
= 800Ω
LTC4065L
LTC4065L
LTC4065L
LTC4065L-4.1
LTC4065L-4.1
5
LTC4065L-4.1
–25
0
50
75
100
–50
25
50
100
200
0
250
4
4.5
5.5
6
150
(mA)
TEMPERATURE (°C)
I
SUPPLY VOLTAGE (V)
BAT
4065L G02
4065L G01
4065L G03
Charge Current vs Temperature
with Thermal Regulation
(Constant Current Mode)
Charge Current vs Supply Voltage
(Constant Current Mode)
Charge Current vs Battery Voltage
30
25
20
15
10
5
300
250
300
250
200
150
100
50
V
T
= 5V
R
V
A
= 13.3k
CC
A
R
PROG
BAT
LTC4065L
= 25°C
= 3.8V
= 800Ω
T
= 25°C
PROG
200
150
THERMAL CONTROL
LOOP IN OPERATION
100
50
0
V
V
= 5V
CC
= 3.8V
BAT
R
= 800Ω
PROG
LTC4065L-4.1
0
0
4
4.5
5
5.5
6
0
1
2
3
4
5
100
–50
0
50
150
V
(V)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
BAT
4065L G04
4065L G05
4065L G06
Power FET On Resistance
vs Temperature
PROG Pin Voltage vs Temperature
(Constant Current Mode)
PROG Pin Voltage
vs Charge Current
1.02
1.01
1.00
0.99
0.98
1.2
1.0
2.0
1.8
1.6
1.4
V
T
= 5V
V
I
= 4V
CC
BAT
V
V
= 5V
CC
A
R
CC
= 25°C
= 150mA
= 3.8V
BAT
= 800Ω
R
= 13.3k
PROG
PROG
0.8
0.6
0.4
0.2
0
1.2
1.0
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
0
50
100
I
150
(mA)
200
250
–50
0
25
50
75
100
–25
TEMPERATURE (°C)
BAT
4065L G07
4065L G08
4065L G09
4065lfb
5
LTC4065L/
LTC4065LX/LTC4065L-4.1
TYPICAL PERFORMANCE CHARACTERISTICS
Manual Shutdown Threshold
Voltage vs Temperature
Manual Shutdown Supply Current
vs Temperature
Undervoltage Lockout Threshold
Voltage vs Temperature
1.0
0.9
0.8
0.7
0.6
0.5
4.00
3.75
3.50
3.25
3.00
2.75
2.50
40
30
20
10
V
V
= 5V
= 5V
CC
EN
RISE
FALL
RISE
FALL
0
–50
0
25
50
75
100
50
TEMPERATURE (°C)
100
–25
–50
–25
0
25
75
–50
–25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
4065L G10
4065L G11
4065L G12
Trickle Charge Current vs Supply
Voltage (4065L and 4065L-4.1)
Trickle Charge Current vs
Temperature (4065L and 4065L-4.1)
EN Pin Current
30
25
20
15
10
5
30
25
20
15
4.0
3.5
3.0
2.5
V
T
= 2V
V
T
= 5V
V
V
= 5V
= 2V
BAT
A
CC
A
CC
BAT
= 25°C
= 25°C
R
= 800Ω
R
= 800Ω
PROG
PROG
2.0
1.5
10
5
1.0
0.5
0
R
= 13.3k
R
PROG
= 13.3k
PROG
0
0
50
TEMPERATURE (°C)
100
4
4.5
5
5.5
6
–50
–25
0
25
75
2.5
3
4
2
4.5
5
3.5
(V)
SUPPLY VOLTAGE (V)
V
EN
4065L G14
4065L G15
4065L G13
CHRG Pin Output Low Voltage
vs Temperature
Timer Accuracy vs Temperature
Timer Accuracy vs Supply Voltage
140
120
1
0
2.0
1.5
V
= 5V
= 5mA
CC
T = 25°C
A
V
= 5V
CC
I
CHRG
–1
–2
1.0
100
80
60
0.5
–3
–4
0
–0.5
–1.0
–1.5
–2.0
40
–5
–6
–7
20
0
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
–25
0
50
4
4.5
5
5.5
6
–50
75
100
25
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
4065L G16
4065L G18
4065L G19
4065lfb
6
LTC4065L/
LTC4065LX/LTC4065L-4.1
PIN FUNCTIONS
GND (Pin 1, Exposed Pad Pin 7): Ground. The Exposed
Pad must be soldered to the PCB ground to provide both
electrical contact and rated thermal performance.
to 5.5V. This pin should be bypassed with at least a 1μF
capacitor. When V is within 32mV of the BAT pin volt-
CC
age, the LTC4065L enters shutdown mode, dropping I
BAT
to about 1μA.
CHRG (Pin 2): Open-Drain Charge Status Output. The
charge status indicator pin has three states: pull-down,
pulse at 2Hz and high impedance state. This output can
be used as a logic interface or as an LED driver. When the
battery is being charged, the CHRG pin is pulled low by
an internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current, the CHRG pin is
forced to a high impedance state. If the battery voltage
remains below 2.9V for one quarter of the charge time, the
battery is considered defective and the CHRG pin pulses
at a frequency of 2Hz.
EN (Pin 5): Enable Input Pin. Pulling this pin above the
manual shutdown threshold (V is typically 0.82V) puts
MS
the LTC4065L in shutdown mode. In shutdown mode, the
LTC4065Lhaslessthan20μAsupplycurrentandlessthan
1μA battery drain current. Enable is the default state, but
the pin should be tied to GND if unused.
PROG (Pin 6): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor, R
, to
PROG
ground programs the charge current. When charging in
constant-currentmode,thispinservosto1V.Inallmodes,
the voltage on this pin can be used to measure the charge
current using the following formula:
BAT (Pin 3): Charge Current Output. Provides charge cur-
renttothebatteryandregulatesthefinalfloatvoltage(4.2V
for LTC4065L/LTC4065LX and 4.1V for LTC4065L-4.1).
An internal precision resistor divider on this pin sets the
float voltage and is disconnected in shutdown mode.
V
PROG
IBAT
=
• 205
RPROG
V
(Pin 4): Positive Input Supply Voltage. This pin pro-
CC
Floating the PROG pin sets the charge current to zero.
vides power to the charger. V can range from 3.75V
CC
4065lfb
7
LTC4065L/
LTC4065LX/LTC4065L-4.1
SIMPLIFIED BLOCK DIAGRAM
V
CC
4
V
CC
T
+
–
DIE
D3
TA
+
–
115°C
UVLO
BAT
C2
M2
1×
M1
205×
3.6V
EN
5
+
R
SHUTDOWN
ENB
C1
D1
D2
0.82V
–
3
+
–
+
MA
R1
R2
1.2V
REF
CA
VA
PROG
0.1V
–
+
–
+
R3
1V
–
+
1.2V
MP
C/10
R4
R5
0.1V
CHARGE CONTROL
LOGIC
CHRG
2
COUNTER
ENABLE
–
2.9V
LOBAT
+
SHUTDOWN
BAT
OSCILLATOR
PROG
GND
6
1
4056L F01
TRICKLE CHARGE DISABLED ON THE LTC4065LX
R
PROG
Figure 1. LTC4065L Block Diagram
4065lfb
8
LTC4065L/
LTC4065LX/LTC4065L-4.1
OPERATION
TheLTC4065Lisalinearbatterychargerdesignedprimar-
ily for charging single cell lithium-ion batteries. Featuring
an internal P-channel power MOSFET, the charger uses a
constant-current/constant-voltage charge algorithm with
programmablecurrent.Chargecurrentcanbeprogrammed
up to 250mA with a final float voltage accuracy of 0.6%.
The CHRG open-drain status output indicates if C/10 has
been reached. No blocking diode or external sense resis-
tor is required; thus, the basic charger circuit requires
only two external components. An internal termination
timer and trickle charge low-battery conditioning adhere
to battery manufacturer safety guidelines (Note: The
LTC4065LX does not include this trickle charge feature).
Furthermore, the LTC4065L is capable of operating from
a USB power source.
When the BAT pin approaches the final float voltage (4.2V
forLTC4065L/LTC4065LXor4.1VforLTC4065L-4.1), the
LTC4065L enters constant-voltage mode and the charge
current begins to decrease. When the current drops to
10% of the full-scale charge current, an internal compara-
tor turns off the N-channel MOSFET on the CHRG pin and
the pin assumes a high impedance state.
An internal timer sets the total charge time, t
(typi-
TIMER
cally 4.5 hours). When this time elapses, the charge cycle
terminates and the CHRG pin assumes a high impedance
state. To restart the charge cycle, remove the input voltage
and reapply it or momentarily force the EN pin above V
MS
(typically0.82V).Thechargecyclewillautomaticallyrestart
if the BAT pin voltage falls below V (typically 4.1V).
RECHRG
When the input voltage is not present, the battery drain
currentisreducedtolessthan4μA.TheLTC4065Lcanalso
be shut down by pulling the EN pin above the shutdown
threshold voltage. This reduces input quiescent current to
less than 20μA and battery drain current to less than 1μA.
An internal thermal limit reduces the programmed charge
current if the die temperature attempts to rise above a
presetvalueofapproximately115°C. Thisfeatureprotects
the LTC4065L from excessive temperature and allows the
usertopushthelimitsofthepowerhandlingcapabilityofa
givencircuitboardwithoutriskofdamagingtheLTC4065L
or external components. Another benefit of the LTC4065L
thermal limit is that charge current can be set according
to typical, not worst-case, ambient temperatures for a
given application with the assurance that the charger will
automaticallyreducethecurrentinworst-caseconditions.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The battery charge current
is 205 times the current out of the PROG pin. The program
resistor and the charge current are calculated using the
following equations:
The charge cycle begins when the following conditions
1V
IBAT
205V
RPROG
are met: the voltage at the V pin exceeds 3.6V and ap-
CC
RPROG = 205 •
,IBAT =
proximately 80mV above the BAT pin voltage, a program
resistor is present from the PROG pin to ground and the
EN pin is pulled below the shutdown threshold (typically
0.82V).
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage and using
the following equation:
If the BAT pin voltage is below 2.9V, the charger goes into
trickle charge mode, charging the battery at one-tenth the
programmed charge current to bring the cell voltage up
to a safe level for charging (Note: The LTC4065LX does
not include this trickle charge feature). If the BAT pin volt-
age is above 4.1V for LTC4065L/LTC4065LX or 4.0V for
LTC4065L-4.1, the charger will not charge the battery as
the cell is near full capacity. Otherwise, the charger goes
into the fast charge constant-current mode.
V
PROG
IBAT
=
•205
RPROG
4065lfb
9
LTC4065L/
LTC4065LX/LTC4065L-4.1
OPERATION
Undervoltage Lockout (UVLO)
falls 100mV below the float voltage (which corresponds
to 80% to 90% battery capacity), a new charge cycle is
initiated and a 2.25 hour timer begins. This ensures that
the battery is kept at, or near, a fully charged condition and
eliminates the need for periodic charge cycle initiations.
TheCHRGoutputassumesastrongpull-downstateduring
recharge cycles until C/10 is reached when it transitions
to a high impendance state.
Aninternalundervoltagelockoutcircuitmonitorstheinput
voltageandkeepsthechargerinundervoltagelockoutuntil
V
rises above 3.6V and approximately 80mV above the
CC
BAT pin voltage. The 3.6V UVLO circuit has a built-in hys-
teresisofapproximately0.6Vandtheautomaticshutdown
thresholdhasabuilt-inhysteresisofapproximately50mV.
Duringundervoltagelockoutconditions,maximumbattery
draincurrentis4μAandmaximumsupplycurrentis11μA.
Trickle Charge and Defective Battery Detection
Shutdown Mode
At the beginning of a charge cycle, if the battery voltage
is low (below 2.9V), the charger goes into trickle charge,
reducing the charge current to 10% of the full-scale cur-
rent (Note: The LTC4065LX has full charge current at
low-battery voltage). If the low-battery voltage persists
for one quarter of the total time (1.125 hour), the battery
is assumed to be defective, the charge cycle is terminated
and the CHRG pin output pulses at a frequency of 2Hz with
a 75% duty cycle. If for any reason the battery voltage
rises above 2.9V, the charge cycle will be restarted. To
restart the charge cycle (i.e., when the defective battery
is replaced with a discharged battery), simply remove the
input voltage and reapply it or temporarily pull the EN pin
above the shutdown threshold.
The LTC4065L can be disabled by pulling the EN pin
above the shutdown threshold (approximately 0.82V).
In shutdown mode, the battery drain current is reduced
to less than 1μA and the supply current to about 20μA.
Timer and Recharge
The LTC4065L has an internal termination timer that
starts when an input voltage greater than the undervolt-
age lockout threshold is applied to VCC, or when leaving
shutdown the battery voltage is less than the recharge
threshold.
At power-up or when exiting shutdown, if the battery volt-
age is less than the recharge threshold, the charge time is
set to 4.5 hours. If the battery voltage is greater than the
rechargethresholdatpower-uporwhenexitingshutdown,
the timer will not start and charging is prevented since the
battery is at or near full capacity.
CHRG Status Output Pin
The charge status indicator pin has three states: pull-
down, pulse at 2Hz (see Trickle Charge and Defective
Battery Detection) and high impedance. The pull-down
state indicates that the LTC4065L is in a charge cycle. A
high impedance state indicates that the charge current
has dropped below 10% of the full-scale current or the
LTC4065L is disabled. Figure 2 shows the CHRG status
under various conditions.
Once the charge cycle terminates, the LTC4065L continu-
ously monitors the BAT pin voltage using a comparator
with a 2ms filter time. When the average battery voltage
4065lfb
10
LTC4065L/
LTC4065LX/LTC4065L-4.1
OPERATION
Charge Current Soft-Start and Soft-Stop
loop, whichever is trying to reduce the charge current
the most. The output of the other amplifier saturates low
which effectively removes its loop from the system. When
in constant-current mode, CA servos the voltage at the
PROG pin to be precisely 1V. VA servos its inverting input
to an internal reference voltage when in constant-voltage
mode and the internal resistor divider, made up of R1 and
R2, ensures that the battery voltage is maintained at 4.2V
for LTC4065L/LTC4065LX or 4.1V for LTC4065L-4.1. The
PROGpinvoltagegivesanindicationofthechargecurrent
during constant-voltage mode as discussed in “Program-
ming Charge Current”.
The LTC4065L includes a soft-start circuit to minimize
the inrush current at the start of a charge cycle. When a
charge cycle is initiated, the charge current ramps from
zerotothefull-scalecurrentoveraperiodofapproximately
170μs.Likewise,internalcircuitryslowlyrampsthecharge
current from full-scale to zero when the charger is shut off
or self terminates. This has the effect of minimizing the
transient current load on the power supply during start-up
and charge termination.
Constant-Current/Constant-Voltage/
Constant-Temperature
Thetransconductanceamplifier,TA,limitsthedietempera-
turetoapproximately115°Cwheninconstant-temperature
mode. DiodeD3ensuresthatTAdoesnotaffectthecharge
current when the die temperature is below approximately
115°C. The PROG pin voltage continues to give an indica-
tion of the charge current.
The LTC4065L use a unique architecture to charge a bat-
tery in a constant-current, constant-voltage and constant-
temperature fashion. Figure 1 shows a simplified block
diagram of the LTC4065L. Three of the amplifier feedback
loops shown control the constant-current, CA, constant-
voltage,VA,andconstant-temperature,TAmodes.Afourth
amplifierfeedbackloop,MA,isusedtoincreasetheoutput
impedanceofthecurrentsourcepair;M1andM2(notethat
M1 is the internal P-channel power MOSFET). It ensures
that the drain current of M1 is exactly 205 times greater
than the drain current of M2.
In typical operation, the charge cycle begins in constant-
currentmodewiththecurrentdeliveredtothebatteryequal
. If the power dissipation of the LTC4065L
PROG
to 205V/R
results in the junction temperature approaching 115°C,
the amplifier (TA) will begin decreasing the charge current
to limit the die temperature to approximately 115°C. As
the battery voltage rises, the LTC4065L either returns to
constant-current mode or enters constant-voltage mode
straight from constant-temperature mode. Regardless of
mode, the voltage at the PROG pin is proportional to the
current delivered to the battery.
Amplifiers CA and VA are used in separate feedback loops
to force the charger into constant-current or constant-
voltage mode, respectively. Diodes D1 and D2 provide
priority to either the constant-current or constant-voltage
4065lfb
11
LTC4065L/
LTC4065LX/LTC4065L-4.1
OPERATION
ENABLE
UVLO
IF V > 3.6V AND
UVLO MODE
NO
NO
POWER
IS EN > SHUTDOWN
THRESHOLD?
CHRG HIGH IMPEDANCE
CC
ON
V
CC
> V
BAT
+ 80mV?
YES
YES
SHUTDOWN MODE
CHRG HIGH IMPEDANCE
V
V
> 4.1V (LTC4065L/LTC4065LX)
> 4.0V (LTC4065L-4.1)
BAT
BAT
V
≤ 2.9V
2.9V < V
< 4.1V (LTC4065L/LTC4065LX)
< 4.0V (LTC4065L-4.1)
BAT
BAT
BAT
2.9V < V
FAST CHARGE MODE
FULL CHARGE CURRENT
TRICKLE CHARGE MODE*
STANDBY MODE
1/10 FULL CHARGE CURRENT
NO CHARGE CURRENT
CHRG STRONG PULL-DOWN
CHRG STRONG PULL-DOWN
CHRG HIGH IMPEDANCE
1/4 CHARGE CYCLE
(1.125 HOURS)
NO
CHARGE CYCLE
(4.5 HOURS)
NO
DEFECTIVE BATTERY
< 2.9V?
RECHARGE
IS V
IS V
IS V
< 4.1V? (LTC4065L/LTC4065LX)
< 4.0V? (LTC4065L-4.1)
BAT
BAT
BAT
YES
BAD BATTERY MODE
YES
RECHARGE MODE
NO CHARGE CURRENT
FULL CHARGE CURRENT
CHRG PULSES (2Hz)
CHRG STRONG PULL-DOWN
V
< 3V
CC
1/2 CHARGE CYCLE
(2.25 HOURS)
OR
EN > SHDN
THRESHOLD
4065L F02
*LTC4065L and LTC4065L-4.1 ONLY; LTC4065LX HAS FULL CHARGE CURRENT.
Figure 2. State Diagram of LTC4065L Operation
4065lfb
12
LTC4065L/
LTC4065LX/LTC4065L-4.1
APPLICATIONS INFORMATION
Undervoltage Charge Current Limiting (UVCL)
The LTC4065L includes undervoltage charge (ΔV
current limiting that prevents full charge current until the
inputsupplyvoltagereachesapproximately200mVabove
the battery voltage. This feature is particularly useful if the
LTC4065L is powered from a supply with long leads (or
any relatively high output impedance).
USB and Wall Adapter Power
)
Although the LTC4065L allows charging from a USB port,
a wall adapter can also be used to charge Li-Ion batteries.
Figure 3 shows an example of how to combine wall adapter
and USB power inputs. A P-channel MOSFET, MP1, is
used to prevent back conducting into the USB port when a
wall adapter is present and Schottky diode, D1, is used to
preventUSBpowerlossthroughthe1kpull-downresistor.
UVCL1
For example, USB-powered systems tend to have highly
variablesourceimpedances(dueprimarilytocablequality
and length). A transient load combined with such imped-
ance can easily trip the UVLO threshold and turn the
charger off unless undervoltage charge current limiting
is implemented.
Stability Considerations
TheLTC4065Lcontainstwocontrolloops:constant-voltage
and constant-current. The constant-voltage loop is stable
without any compensation when a battery is connected
withlowimpedanceleads.Excessiveleadlength,however,
may add enough series inductance to require a bypass
capacitor of at least 1μF from BAT to GND. Furthermore,
a 4.7μF capacitor with a 0.2Ω to 1Ω series resistor from
BAT to GND is required to keep ripple voltage low when
the battery is disconnected.
Consider a situation where the LTC4065L is operating
under normal conditions and the input supply voltage
begins to droop (e.g., an external load drags the input
supplydown). IftheinputvoltagereachesVBAT +ΔVUVCL1
(approximately 220mV above the battery voltage), un-
dervoltage charge current limiting will begin to reduce
the charge current in an attempt to maintain ΔVUVCL1
between the VCC input and the BAT output of the IC. The
LTC4065L will continue to operate at the reduced charge
current until the input supply voltage is increased or volt-
age mode reduces the charge current further.
High value capacitors with very low ESR (especially ce-
ramic)mayreducetheconstant-voltageloopphasemargin.
Ceramic capacitors up to 22μF may be used in parallel
with a battery, but larger ceramics should be decoupled
with 0.2Ω to 1Ω of series resistance.
I
5V WALL
ADAPTER
BAT
3
6
SYSTEM
LOAD
BAT
LTC4065L
D1
4
USB
POWER
V
CC
MP1
+
Li-Ion
BATTERY
PROG
1k
800Ω
4065L F03
Figure 3. Combining Wall Adapter and USB Power
4065lfb
13
LTC4065L/
LTC4065LX/LTC4065L-4.1
APPLICATIONS INFORMATION
In constant-current mode, the PROG pin is in the feedback
loop,notthebattery.Becauseoftheadditionalpolecreated
bythePROGpincapacitance,capacitanceonthispinmust
be kept to a minimum. With no additional capacitance on
the PROG pin, the charger is stable with program resistor
values as high as 25k. However, additional capacitance on
this node reduces the maximum allowed program resis-
tor. The pole frequency at the PROG pin should be kept
above 100kHz. Therefore, if the PROG pin is loaded with
battery current as shown in Figure 4. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
Power Dissipation
Due to the low charge currents, it is unlikely that the
LTC4065L will reduce charge current through thermal
feedback. Nonetheless, the LTC4065L power dissipation
can be approximated by:
a capacitance, C
, the following equation should be
PROG
P = (V – V ) • I
BAT
D
CC
BAT
usedtocalculatethemaximumresistancevalueforR
:
PROG
Where P is the power dissipated, V is the input supply
D
CC
1
RPROG
≤
voltage, V is the battery voltage and I is the charge
2π •105 •CPROG
BAT
BAT
current. It is not necessary to perform any worst-case
power dissipation scenarios because the LTC4065L will
automatically reduce the charge current to maintain the
die temperature at approximately 115°C. However, the
approximate ambient temperature at which the thermal
feedback begins to protect the IC is:
Average,ratherthaninstantaneous,batterycurrentmaybe
of interest to the user. For example, if a switching power
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
T = 115°C – P • θ
JA
A
D
T = 115°C – (V – V ) • I • θ
A
CC
BAT
BAT
JA
LTC4065L
CHARGE
10k
CURRENT
MONITOR
CIRCUITRY
PROG
GND
R
C
FILTER
PROG
4065L F04
Figure 4. Isolating Capacitive Load on the PROG Pin and Filtering
4065lfb
14
LTC4065L/
LTC4065LX/LTC4065L-4.1
APPLICATIONS INFORMATION
Example: Consider an LTC4065L operating from a 5.5V
wall adapter providing 250mA to a 3V Li-Ion battery. The
ambienttemperatureabovewhichtheLTC4065Lwillbegin
to reduce the 250mA charge current is approximately:
Board Layout Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on
the backside of the LTC4065L package is soldered to
2
T = 115°C – (5.5V – 3V) • (250mA) • 60°C/W
A
the PC board ground. Correctly soldered to a 2500mm
double-sided 1 oz. copper board the LTC4065L has a
thermal resistance of approximately 60°C/W. Failure to
make thermal contact between the Exposed Pad on the
backside of the package and the copper board will result
in thermal resistances far greater than 60°C/W.
T = 115°C – 0.625W • 60°C/W = 115°C – 37.5°C
A
T = 77.5°C
A
Chargingatsuchhighambienttemperaturesisnotrecom-
mended by battery manufacturers.
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in
the Programming Charge Current section.
V
Bypass Capacitor
CC
Many types of capacitors can be used for input bypassing;
however,cautionmustbeexercisedwhenusingmulti-layer
ceramic capacitors. Because of the self-resonant and high
Qcharacteristicsofsometypesofceramiccapacitors,high
voltage transients can be generated under some start-up
conditions, such as connecting the charger input to a live
power source. For more information, refer to Application
Note 88.
It is important to remember that LTC4065L applications
do not need to be designed for worst-case thermal
conditions since the IC will automatically reduce power
dissipation when the junction temperature reaches ap-
proximately 115°C.
4065lfb
15
LTC4065L/
LTC4065LX/LTC4065L-4.1
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703)
R = 0.115
TYP
0.56 0.05
(2 SIDES)
0.38 0.05
4
6
0.675 0.05
2.50 0.05
2.00 0.10
(4 SIDES)
0.61 0.05
(2 SIDES)
1.15 0.05
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
PIN 1
PACKAGE
OUTLINE
CHAMFER OF
EXPOSED PAD
(DC6) DFN 1103
3
1
0.25 0.05
0.25 0.05
0.50 BSC
0.50 BSC
0.75 0.05
0.200 REF
1.37 0.05
(2 SIDES)
1.42 0.05
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
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
4065lfb
16
LTC4065L/
LTC4065LX/LTC4065L-4.1
REVISION HISTORY (Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
05/12 Added new part number LTC4065L-4.1
Added Options Table & Updated Order Information Table
Clarified Note 2 testing conditions
Throughout
2
4
Clarified State Diagram
12
4065lfb
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
17
LTC4065L/
LTC4065LX/LTC4065L-4.1
RELATED PARTS
PART NUMBER
Battery Chargers
LTC1734
DESCRIPTION
COMMENTS
TM
Lithium-Ion Linear Battery Charger in ThinSOT
Lithium-Ion Linear Battery Charger in ThinSOT
Lithium-Ion Linear Battery Charger Controller
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
LTC1734L
Low Current Version of LTC1734, 50mA ≤ I
≤ 180mA
CHRG
LTC4050
Features Preset Voltages, C/10 Charger Detection and Programmable
Timer, Input Power Good Indication, Thermistor Interface
LTC4054
LTC4054L
LTC4057
Standalone Linear Li-Ion Battery Charger
with Integrated Pass Transistor in ThinSOT
Thermal Regulation Prevents Overheating, C/10 Termination,
C/10 Indicator, Up to 800mA Charge Current
Standalone Linear Li-Ion Battery Charger
with Integrated Pass Transistor in ThinSOT
Low Current Version of LTC4054, Charge Current Up to 150mA
Lithium-Ion Linear Battery Charger
Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package
LTC4059/
LTC4059A
900mA Linear Lithium-Ion Battery Charger
2mm × 2mm DFN Package, Thermal Regulation, Charge Current Monitor
Output. A Version has ACPR Function
LTC4061
Standalone Li-Ion Charger with Thermistor Interface
Standalone Li-Ion Charger with Thermistor Interface
4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm × 3mm DFN
LTC4061-4.4
4.4V (Max), 0.4% Float Voltage, Up to 1A Charge Current,
3mm × 3mm DFN
LTC4062
LTC4063
Standalone Linear Li-Ion Battery Charger with
Micropower Comparator
4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm × 3mm DFN
Up to 1A Charge Current, 100mA, 125mV LDO, 3mm × 3mm DFN
LI-Ion Charger with Linear Regulator
Standalone Li-Ion Battery Chargers
LTC4065/
LTC4065A
4.2V, 0.6% Float Voltage, Up to 750mA Charge Current,
2mm × 2mm DFN; “A” Version Has ACPR Function
Power Management
LTC3405/
LTC3405A
300mA (I ), 1.5MHz, Synchronous Step-Down
95% Efficiency, V : 2.7V to 6V, V
= 0.8V, I = 20μA, I < 1μA,
OUT Q SD
OUT
IN
DC/DC Converter
ThinSOT Package
LTC3406/
LTC3406A
600mA (I ), 1.5MHz, Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
= 0.6V, I = 20μA, I < 1μA,
Q SD
OUT
IN
OUT
OUT
OUT
DC/DC Converter
ThinSOT Package
LTC3411
1.25A (I ), 4MHz, Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
= 0.8V, I = 60μA, I < 1μA,
Q SD
OUT
IN
DC/DC Converter
MS Package
LTC3440
600mA (I ), 2MHz, Synchronous Buck-Boost
95% Efficiency, V : 2.5V to 5.5V, V
= 2.5V, I = 25μA, I < 1μA,
Q SD
OUT
IN
DC/DC Converter
MS Package
TM
LTC4411/LTC4412 Low Loss PowerPath Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
LTC4413
Dual Ideal Diode in DFN
2-Channel Ideal Diode ORing, Low Forward ON Resistance, Low Regulated
Forward Voltage, 2.5V ≤ V ≤ 5.5V
IN
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
4065lfb
LT 0512 REV B • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
18
●
●
© LINEAR TECHNOLOGY CORPORATION 2005
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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