LTC4065_15 [Linear]
Standalone 750mA Li-Ion Battery Charger;
| 型号： | LTC4065_15 |
| 厂家： | 
Linear |
| 描述： | Standalone 750mA Li-Ion Battery Charger 电池 |
| 文件： | 总16页 (文件大小：225K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC4065/LTC4065A
Standalone 750mA Li-Ion
Battery Charger in 2 × 2 DFN
U
FEATURES
DESCRIPTIO
The LTC®4065 is a complete constant-current/constant-
voltage linear charger for single-cell lithium-ion batteries.
Its2mm× 2mmDFNpackageandlowexternalcomponent
count make the LTC4065 especially well-suited for por-
table applications. Furthermore, LTC4065 is specifically
designed to work within USB power specifications.
■
Complete Linear Charger in 2mm × 2mm DFN
Package
■
C/10 Charge Current Detection Output
■
Timer Termination
■
Charge Current Programmable up to 750mA with
5% Accuracy
■
No External MOSFET, Sense Resistor or Blocking
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.
Diode Required
■
Preset 4.2V Float Voltage with 0.6% Accuracy
■
Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
No external sense resistor or blocking diode is required
due to the internal MOSFET architecture. Thermal feed-
back regulates charge current to limit the die temperature
during high power operation or high ambient temperature
conditions.
■
ACPR Pin Indicates Presence of Input Supply
(LTC4065A Only)
■
Charge Current Monitor Output for Gas Gauging
■
Automatic Recharge
■
Charges Single Cell Li-Ion Batteries Directly from
When the input supply (wall adapter or USB supply) is
removed, the LTC4065 automatically enters a low current
state,droppingbatterydraincurrenttolessthan1µA.With
power applied, LTC4065 can be put into shutdown mode,
reducing the supply current to less than 20µA.
USB Port
■
20µA Supply Current in Shutdown Mode
■
Soft-Start Limits Inrush Current
■
Tiny 6-Lead (2mm × 2mm) DFN Package
U
APPLICATIO S
The full-featured LTC4065 also includes automatic re-
charge, low-battery charge conditioning (trickle charg-
ing), soft-start (to limit inrush current) and an open-drain
status pin to indicate the presence of an adequate input
voltage (LTC4065A only).
■
Wireless PDAs
■
Cellular Phones
■
Portable Electronics
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LTC4065 is available in a tiny 6-lead, low profile
(0.75mm) 2mm × 2mm DFN package.
U
TYPICAL APPLICATIO
Standalone Li-Ion Battery Charger
500mA
V
IN
V
BAT
LTC4065
CHRG PROG
EN GND
CC
4.3V TO 5.5V
R1
510Ω
4.2V
Li-Ion
BATTERY
C1
1µF
+
R3
2k
R2*
1Ω
4065 TA01
*SERIES 1Ω RESISTOR ONLY NEEDED FOR INDUCTIVE INPUT SUPPLIES
4065fb
1
LTC4065/LTC4065A
W W
U W
U W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
VCC
t < 1ms and Duty Cycle < 1% ................. –0.3V to 7V
Steady State ........................................... –0.3V to 6V
BAT, CHRG ................................................. –0.3V to 6V
EN (LTC4065), ACPR (LTC4065A).. –0.3V to VCC + 0.3V
PROG.............................................. –0.3V to VCC + 0.3V
BAT Short-Circuit Duration ...........................Continuous
BAT Pin Current ................................................. 800mA
PROG Pin Current............................................... 800µA
Junction Temperature (Note 6)............................ 125°C
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................ –65°C to 125°C
GND
CHRG
BAT
1
2
3
6
5
4
PROG
7
EN/ACPR*
V
CC
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
TJMAX = 125°C, θJA = 60°C/W (NOTE 3)
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
*EN PIN 5 ON LTC4065EDC, ACPR PIN 5 ON LTC4065AEDC
DC PART MARKING
ORDER PART NUMBER
LBPG
LBVJ
LTC4065EDC
LTC4065AEDC
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
CC
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V
= 5V, V
= 3.8V, V = 0V (LTC4065 only) unless otherwise specified. (Note 2)
EN
BAT
PARAMETER
Supply Voltage
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.5
250
40
UNITS
V
V
CC
V
CC
(Note 4)
●
●
●
●
3.75
I
I
I
Quiescent V Supply Current
V
V
V
= 4.5V (Forces I
and I = 0)
PROG
120
20
6
µA
µA
CC
CC
BAT
BAT
V
V
Supply Current in Shutdown
= 5V (LTC4065) or Float PROG (LTC4065A)
CCMS
CCUV
CC
EN
CC
Supply Current in Undervoltage
< V , V = 3.5V, V
= 4V
BAT
11
µA
CC
BAT CC
Lockout
V
FLOAT
V
BAT
Regulated Output Voltage
I
I
= 2mA
= 2mA, 0°C < T < 85°C
4.175
4.158
4.2
4.2
4.225
4.242
V
V
BAT
BAT
A
I
I
I
BAT Pin Current
R
R
= 10k (0.1%), Current Mode
= 2k (0.1%), Current Mode
●
●
88
475
100
500
112
525
mA
mA
BAT
PROG
PROG
Battery Drain Current in Shutdown
Mode
V
V
= V (LTC4065),
●
–1
0
1
µA
BMS
BUV
EN
CC
> V
(LTC4065A)
PROG
MS,PROG
Battery Drain Current in Undervoltage V = 3.5V, V
Lockout
= 4V
●
0
1
4
µA
CC
BAT
V
V
V
V
V
V
Undervoltage Lockout Voltage
V
V
Rising
Falling
●
●
3.4
2.8
3.6
3.0
3.8
3.2
V
V
UVLO
PROG
ASD
CC
CC
CC
PROG Pin Voltage
R
R
= 2k, I
= 10k, I
= 500µA
PROG
●
●
0.98
0.98
1
1
1.02
1.02
V
V
PROG
PROG
PROG
= 100µA
Automatic Shutdown Threshold
Voltage
(V – V ), V Low to High
(V – V ), V High to Low
60
15
82
32
100
45
mV
mV
CC
BAT
CC
CC
BAT
CC
Manual Shutdown High Voltage
(LTC4065)
V
V
Rising
1
V
MSH
MSL
EN
EN
Manual Shutdown Low Voltage
(LTC4065)
Falling
0.6
V
R
EN
EN Pin Input Resistance
●
0.95
1.5
3.3
MΩ
4065fb
2
LTC4065/LTC4065A
ELECTRICAL CHARACTERISTICS
The
CC
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V
= 5V, V
= 3.8V, V = 0V (LTC4065 only) unless otherwise specified. (Note 2)
EN
BAT
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
PROG Pin Pull-Up Current
(LTC4065A)
V
> 1V
3
µA
PROG
PROG
V
PROG Shutdown Threshold Voltage
(LTC4065A Only)
V
Rising
●
●
3.7
4
4.3
V
MS,PROG
PROG
t
I
Soft-Start Time
180
50
µs
mA
V
SS
TRKL
Trickle Charge Current
V
V
= 2V, R
Rising
= 2k (0.1%)
35
65
BAT
BAT
PROG
V
V
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
Recharge Battery Threshold Voltage
2.7
2.9
90
3.05
TRKL
mV
mV
TRHYS
∆V
V
– V
, 0°C < T < 85°C
70
100
130
RECHRG
FLOAT
RECHRG
A
∆V
UVCL1
∆V
UVCL2
(V – V ) Undervoltage Current
Limit
I
I
= 90% Programmed Charge Current
= 10% Programmed Charge Current
180
90
220
125
330
150
mV
mV
CC
BAT
BAT
BAT
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
V
= 2.5V
0.75
1.5
105
BAT
V
ACPR Pin Output Low Voltage
(LTC4065A)
I
= 5mA
ACPR
ACPR
I
ACPR Pin Input Current (LTC4065A)
CHRG Pin Output Low Voltage
CHRG Pin Input Current
V
= 4V, V
= 4V, V = 4.5V
BAT
●
●
●
●
0
60
0
1
105
1
µA
mV
ACPR
CC
ACPR
V
I
= 5mA
CHRG
CHRG
C/10
CHRG
I
I
V
= 4.5V, V
= 5V
µA
mA/mA
BAT
CHRG
End of Charge Indication Current
Level
R
= 2k (Note 5)
0.085
0.1
0.115
PROG
T
Junction Temperature in Constant
Temperature Mode
115
450
2
°C
mΩ
Hz
LIM
R
Power FET “ON” Resistance
I
= 200mA
BAT
ON
(Between V and BAT)
CC
f
Defective Battery Detection CHRG
Pulse Frequency
BADBAT
D
Defective Battery Detection CHRG
Pulse Frequency Duty Ratio
75
%
BADBAT
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 LTC4065 functions properly at 3.75V, full charge
current requires an input voltage greater than the desired final battery
voltage per the ∆V
specification.
UVCL1
Note 5: I
is expressed as a fraction of measured full charge current
C/10
Note 2: The LTC4065/LTC4065A 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 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.
with indicated PROG resistor.
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.
4065fb
3
LTC4065/LTC4065A
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Battery Regulation (Float) Voltage
vs Battery Charge Current
Battery Regulation (Float) Voltage
vs Temperature
Regulated Output (Float) Voltage
vs Supply Voltage
4.24
4.24
4.23
4.22
4.21
4.24
4.23
4.22
4.21
4.20
4.19
4.18
4.17
4.16
V
A
R
= 5V
T
BAT
R
= 25°C
CC
A
T
= 25°C
I
= 2mA
4.23
4.22
= 2k
= 2k
PROG
PROG
4.21
4.20
4.19
4.18
4.17
4.20
4.19
4.18
4.17
4.16
4.16
100
200
I
400
–25
0
50
75
100
0
500
–50
25
300
(mA)
4
5
6
4.5
5.5
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
BAT
4065 G01
4065 G02
4065 G03
Charge Current vs Temperature
with Thermal Regulation
(Constant Current Mode)
Charge Current vs Supply Voltage
(Constant Current Mode)
Charge Current vs Battery Voltage
600
500
200
175
150
125
100
75
600
500
400
300
200
100
0
V
T
= 5V
R
V
A
= 10k
BAT
= 25°C
CC
A
R
PROG
= 3.8V
= 25°C
= 2k
T
PROG
400
300
THERMAL CONTROL
LOOP IN OPERATION
200
100
0
50
V
V
= 5V
CC
25
= 3.8V
BAT
R
= 2k
PROG
0
4
4.5
5
5.5
6
100
0
1
2
3
4
5
–50
0
50
150
SUPPLY VOLTAGE (V)
V
(V)
TEMPERATURE (°C)
BAT
4065 G04
4065 G05
4065 G06
Power FET On Resistance
vs Temperature
PROG Pin Voltage vs Temperature
(Constant Current Mode)
PROG Pin Voltage
vs Charge Current
1.2
1.0
550
500
450
400
1.02
1.01
1.00
0.99
0.98
V
T
= 5V
V
I
= 4V
CC
BAT
V
V
= 5V
CC
A
R
CC
= 25°C
= 400mA
= 3.8V
BAT
= 2k
R
= 10k
PROG
PROG
0.8
0.6
0.4
0.2
0
350
300
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
0
100
200
I
300
(mA)
400
500
–50
0
25
50
75
100
–25
TEMPERATURE (°C)
BAT
4065 G07
4065 G08
4065 G09
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LTC4065/LTC4065A
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Manual Shutdown Threshold
Voltage vs Temperature (LTC4065)
Manual Shutdown Supply Current
vs Temperature
Undervoltage Lockout Threshold
Voltage vs Temperature
1.0
0.9
0.8
0.7
0.6
0.5
4.0
3.8
3.5
3.3
3.0
2.8
2.5
40
V
V
= 5V
= 5V
CC
EN
30
20
10
RISE
FALL
RISE
FALL
0
–50
0
25
50
75
100
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4065 G16
4065 G11
4065 G12
Trickle Charge Current
vs Supply Voltage
Trickle Charge Current
vs Temperature
EN Pin Current (LTC4065)
60
50
40
30
20
10
0
4.0
3.5
3.0
2.5
60
50
40
30
V
T
= 2V
V
T
= 5V
BAT
A
V
V
= 5V
= 2V
CC
A
CC
BAT
= 25°C
= 25°C
R
= 2k
PROG
R
= 2k
PROG
2.0
1.5
20
10
0
1.0
0.5
0
R
= 10k
PROG
5
R
= 10k
PROG
4
4.5
5.5
6
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
2.5
3
4
2
4.5
5
3.5
(V)
SUPPLY VOLTAGE (V)
V
EN
4065 G14
4065 G15
4065 G13
CHRG Pin Output Low Voltage
vs Temperature
ACPR Pin Output Low Voltage vs
Temperature (LTC4065A Only)
140
120
140
120
V
I
= 5V
CHRG
V
I
= 5V
ACPR
CC
CC
= 5mA
= 5mA
100
80
60
100
80
60
40
40
20
20
0
0
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
50
TEMPERATURE (°C)
100
–50
–25
0
25
75
4065 G10
4065 G17
4065fb
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LTC4065/LTC4065A
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Timer Accuracy vs Temperature
Timer Accuracy vs Supply Voltage
1
0
2.0
1.5
T
= 25°C
V
= 5V
A
CC
–1
–2
1.0
0.5
0
–3
–4
–0.5
–1.0
–1.5
–2.0
–5
–6
–7
5
4
4.5
5.5
6
–25
0
50
–50
75
100
25
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
4065 G19
4065 G18
PROG Pin Shutdown Threshold vs
Temperature (LTC4065A Only)
PROG Pin Shutdown Voltage vs
Supply Voltage (LTC4065A Only)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
5.0
4.5
4.0
3.5
T
= 25°C
A
V
= 5V
CC
3.0
4
4.5
5
5.5
6
–50
–25
0
25
50
75
100
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
4065 G21
4065 G20
4065fb
6
LTC4065/LTC4065A
U
U
U
PI FU CTIO S
GND (Pin 1): Ground.
ACPR (Pin 5, LTC4065A Only):Open-Drain Power Supply
Status Output. When VCC is greater than the undervoltage
lockoutthreshold(3.6V)andVBAT+80mV(ifVBAT>3.6V),
the ACPR pin will be pulled down to ground; otherwise the
pin is high impedance.
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
batteryisconsidereddefectiveandtheCHRGpinpulsesat
a frequency of 2Hz.
PROG (Pin 6): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor, RPROG, to
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:
VPROG
RPROG
IBAT
=
•1000
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 on this pin
setsthefloatvoltageandisdisconnectedinshutdownmode.
Floating the PROG pin sets the charge current to zero
(LTC4065)orputsthepartinshutdownmode(LTC4065A).
In shutdown mode, the LTC4065A has less than 20µA
supply current and about 1µA battery drain current.
VCC (Pin 4): Positive Input Supply Voltage. This pin
provides power to the charger. VCC can range from 3.75V
to 5.5V. This pin should be bypassed with at least a 1µF
capacitor. When VCC is within 32mV of the BAT pin
voltage, the LTC4065 enters shutdown mode, dropping
IBAT to about 1µA.
Exposed Pad (Pin 7): Ground. The Exposed Pad must be
soldered to the PCB ground to provide both electrical con-
tact and rated thermal performance.
EN (Pin 5, LTC4065 Only): Enable Input Pin. Pulling this
pin above the manual shutdown threshold (VMS is typi-
cally 0.82V) puts the LTC4065 in shutdown mode. In
shutdown mode, the LTC4065 has less than 20µA supply
current and less than 1µA battery drain current. Enable is
the default state, but the pin should be tied to GND if unused.
4065fb
7
LTC4065/LTC4065A
W
W
SI PLIFIED BLOCK DIAGRA S
V
CC
4
V
CC
T
+
–
DIE
D3
TA
+
–
115°C
UVLO
BAT
C2
M2
×1
M1
×1000
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
4056 F01a
R
PROG
Figure 1a. LTC4065 Block Diagram
4065fb
8
LTC4065/LTC4065A
W
W
SI PLIFIED BLOCK DIAGRA S
V
CC
4
V
CC
+
+
–
T
DIE
D3
C2
TA
ACPR
3.6V
–
5
M2
×1
M1
×1000
115°C
+
–
D1
D2
C3
R3
BAT
3
V
+ 80mV
BAT
+
–
+
MA
R1
R2
1.2V
REF
CA
VA
PROG
0.1V
–
+
–
+
1V
–
+
MP
1.2V
C/10
R4
R5
0.1V
CHARGE CONTROL
CHRG
ENABLE
2
LOGIC
COUNTER
–
+
2.9V
+
LOBAT
SHUTDOWN
C1
BAT
4V
–
OSCILLATOR
PROG
GND
6
1
4056 F01b
R
PROG
Figure 1b. LTC4065A Block Diagram
U
OPERATIO
TheLTC4065isalinearbatterychargerdesignedprimarily
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 750mA with a final float voltage accuracy of ±0.6%.
The CHRG open-drain status output indicates if C/10 has
beenreached.Noblockingdiodeorexternalsenseresistor
is required; thus, the basic charger circuit requires only
two external components. The ACPR pin (LTC4065A)
monitorsthestatusoftheinputvoltagewithanopen-drain
output. An internal termination timer and trickle charge
low-battery conditioning adhere to battery manufacturer
safety guidelines. Furthermore, the LTC4065 is capable of
operating from a USB power source.
An internal thermal limit reduces the programmed charge
current if the die temperature attempts to rise above a
presetvalueofapproximately115°C. Thisfeatureprotects
the LTC4065 from excessive temperature and allows the
user to push the limits of the power handling capability of
agivencircuitboardwithoutriskofdamagingtheLTC4065
or external components. Another benefit of the LTC4065
thermal limit is that charge current can be set according to
4065fb
9
LTC4065/LTC4065A
U
OPERATIO
typical, not worst-case, ambient temperatures for a given
application with the assurance that the charger will auto-
matically reduce the current in worst-case conditions.
program resistor and the charge current are calculated
using the following equations:
1V
ICHG
1000V
RPROG
Thechargecyclebeginswhenthefollowingconditionsare
met: the voltage at the VCC pin exceeds 3.6V and approxi-
mately 80mV above the BAT pin voltage, a program
resistorispresentfromthePROGpintogroundandtheEN
pin (LTC4065 only) is pulled below the shutdown thresh-
old (typically 0.82V).
RPROG = 1000 •
, ICHG =
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:
VPROG
RPROG
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. If the BAT pin voltage is above
4.1V, the charger will not charge the battery as the cell is
nearfullcapacity.Otherwise,thechargergoesintothefast
charge constant-current mode.
IBAT
=
•1000
Undervoltage Lockout (UVLO)
Aninternalundervoltagelockoutcircuitmonitorstheinput
voltage and keeps the charger in undervoltage lockout
until VCC rises above 3.6V and approximately 80mV above
the BAT pin voltage. The 3.6V UVLO circuit has a built-in
hysteresis of approximately 0.6V and the automatic shut-
down threshold has a built-in hysteresis of approximately
50mV. During undervoltage lockout conditions, maxi-
mum battery drain current is 4µA and maximum supply
current is 11µA.
When the BAT pin approaches the final float voltage
(4.2V), the LTC4065 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
comparator 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, tTIMER (typi-
cally 4.5 hours). When this time elapses, the charge cycle
terminates and the CHRG pin assumes a high impedance
state. Torestartthechargecycle, removetheinputvoltage
and reapply it, momentarily force the EN pin above VMS
(typically 0.82V) for LTC4065, or momentarily float the
PROG pin and reconnect it (LTC4065A). The charge cycle
will automatically restart if the BAT pin voltage falls below
VRECHRG (typically 4.1V).
Shutdown Mode
The LTC4065 can be disabled by pulling the EN pin above
the shutdown threshold (approximately 0.82V). The
LTC4065A can be disabled by floating the PROG pin. In
shutdown mode, the battery drain current is reduced to
less than 1µA and the supply current to about 20µA.
Timer and Recharge
The LTC4065 has an internal termination timer that starts
when an input voltage greater than the undervoltage
lockout threshold is applied to VCC, or when leaving
shutdown the battery voltage is less than the recharge
threshold.
When the input voltage is not present, the battery drain
current is reduced to less than 4µA. The LTC4065 can also
be shut down by pulling the EN pin above the shutdown
threshold voltage. To put LTC4065A in shutdown mode,
float the PROG pin. This reduces input quiescent current
tolessthan20µAandbatterydraincurrenttolessthan1µA.
At power-up or when exiting shutdown, if the battery
voltage is less than the recharge threshold, the charge
timeissetto4.5hours.Ifthebatteryvoltageisgreaterthan
the recharge threshold at power-up or when exiting shut-
down, the timer will not start and charging is prevented
since the battery is at or near full capacity.
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
4065fb
10
LTC4065/LTC4065A
U
OPERATIO
Once the charge cycle terminates, the LTC4065 continu-
ously monitors the BAT pin voltage using a comparator
with a 2ms filter time. When the average battery voltage
falls below 4.1V (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. The CHRG output
assumes a strong pull-down state during recharge cycles
until C/10 is reached when it transitions to a high
impendance state.
the ACPR pin is high impedance indicating that the
LTC4065A is unable to charge the battery.
Charge Current Soft-Start and Soft-Stop
The LTC4065 includes a soft-start circuit to minimize the
inrushcurrentatthestartofachargecycle. Whenacharge
cycleisinitiated,thechargecurrentrampsfromzerotothe
full-scale current over a period of approximately 180µs.
Likewise, internal circuitry slowly ramps the charge cur-
rent 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.
Trickle Charge and Defective Battery Detection
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
current. 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 dis-
charged battery), simply remove the input voltage and
reapply it, temporarily pull the EN pin above the shutdown
threshold (LTC4065), or momentarily float the PROG pin
and reconnect it (LTC4065A).
Constant-Current/Constant-Voltage/
Constant-Temperature
The LTC4065/LTC4065A use a unique architecture to
charge a battery in a constant-current, constant-voltage
and constant-temperature fashion. Figures 1a and 1b
show simplified block diagrams of the LTC4065 and
LTC4065A, respectively. Three of the amplifier feedback
loops shown control the constant-current, CA, constant-
voltage, VA, and constant-temperature, TA modes. A
fourth amplifier feedback loop, MA, is used to increase the
output impedance of the current source pair; M1 and M2
(note that M1 is the internal P-channel power MOSFET). It
ensures that the drain current of M1 is exactly 1000 times
greater than the drain current of M2.
CHRG Status Output Pin
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
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.
The PROG pin voltage gives an indication of the charge
current during constant-voltage mode as discussed in
“Programming Charge Current”.
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
stateindicatesthattheLTC4065isinachargecycle.Ahigh
impedance state indicates that the charge current has
droppedbelow10%ofthefull-scalecurrentortheLTC4065
isdisabled. Figure2showstheCHRGstatusundervarious
conditions.
Power Supply Status Indicator
(ACPR, LTC4065A Only)
The power supply status output has two states: pull-down
and high impedance. The pull-down state indicates that
VCC is above the undervoltage lockout threshold (see
Undervoltage Lockout). When this condition is not met,
4065fb
11
LTC4065/LTC4065A
U
OPERATIO
ENABLE
UVLO
IF V > 3.6V AND
UVLO MODE
NO
NO
POWER
ON
IS EN > SHUTDOWN
THRESHOLD?
CHRG HIGH IMPEDANCE
CC
V
CC
> V
BAT
+ 80mV?
YES
YES
SHUTDOWN MODE
CHRG HIGH IMPEDANCE
V
BAT
≤ 2.9V
2.9V < V
< 4.1V
V
BAT
> 4.1V
BAT
TRICKLE CHARGE MODE
FAST CHARGE MODE
STANDBY MODE
1/10 FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
NO CHARGE CURRENT
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
< 4.1V?
BAT
BAT
YES
BAD BATTERY MODE
YES
RECHARGE MODE
NO CHARGE CURRENT
CHRG PULSES (2Hz)
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
V
< 3V
CC
1/2 CHARGE CYCLE
(2.25 HOURS)
OR
EN > SHDN
THRESHOLD
4065 F02
Figure 2. State Diagram of LTC4065 Operation
Transconductance amplifier, TA, limits the die tempera-
ture to approximately 115°C when in constant-tempera-
ture mode. Diode D3 ensures that TA does not affect the
chargecurrentwhenthedietemperatureisbelowapproxi-
mately 115°C. The PROG pin voltage continues to give an
indication of the charge current.
LTC4065/LTC4065A results in the junction temperature
approaching 115°C, the amplifier (TA) will begin decreas-
ing the charge current to limit the die temperature to
approximately 115°C. As the battery voltage rises, the
LTC4065/LTC4065Aeitherreturntoconstant-currentmode
or enter 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.
In typical operation, the charge cycle begins in constant-
current mode with the current delivered to the battery
equal to 1000V/RPROG. If the power dissipation of the
4065fb
12
LTC4065/LTC4065A
W U U
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APPLICATIO S I FOR ATIO
Undervoltage Charge Current Limiting (UVCL)
than 600mA. Since the LTC4065 will demand a charge
current higher than the current limit of the voltage supply,
the supply voltage will drop to the battery voltage plus
600mA times the “on” resistance of the internal PFET. The
“on” resistance of the LTC4065 power device is approxi-
mately 450mΩ with a 5V supply. The actual “on” resis-
tance will be slightly higher due to the fact that the input
supply will drop to less than 5V. The power dissipated
during this phase of charging is less than 240mW. That is
a 76% improvement over the non-current limited supply
power dissipation.
The LTC4065/LTC4065A includes undervoltage charge
(∆VUVCL1) current limiting that prevents full charge cur-
rent until the input supply voltage reaches approximately
200mV above the battery voltage. This feature is particu-
larly useful if the LTC4065 is powered from a supply with
long leads (or any relatively high output impedance).
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.
USB and Wall Adapter Power
Although the LTC4065/LTC4065A allow 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
walladapterandUSBpowerinputs. AP-channelMOSFET,
MP1, isusedtopreventbackconductingintotheUSBport
when a wall adapter is present and Schottky diode, D1, is
used to prevent USB power loss through the 1k pull-down
resistor.
Consider a situation where the LTC4065 is operating
under normal conditions and the input supply voltage
begins to droop (e.g., an external load drags the input
supplydown).IftheinputvoltagereachesVBAT +∆VUVCL1
(approximately 220mV above the battery voltage),
undervoltage charge current limiting will begin to reduce
the charge current in an attempt to maintain ∆VUVCL1
between the VCC input and the BAT output of the IC. The
LTC4065 will continue to operate at the reduced charge
current until the input supply voltage is increased or
voltage mode reduces the charge current further.
Typically a wall adapter can supply significantly more
current than the 500mA-limited USB port. Therefore, an
N-channel MOSFET, MN1, and an extra program resistor
areusedtoincreasethechargecurrentto750mAwhenthe
wall adapter is present.
Operation from Current Limited Wall Adapter
5V WALL
By using a current limited wall adapter as the input
supply, the LTC4065 dissipates significantly less power
when programmed for a current higher than the limit of
the supply as compared to using a non-current limited
supply at the same charge current.
I
ADAPTER
750mA
CHG
3
SYSTEM
LOAD
BAT
LTC4065
I
D1
CHG
4
V
USB
POWER
500mA
CC
MP1
6
+
Li-Ion
BATTERY
PROG
4.02k
I
CHG
Consider a situation where an application demands a
600mA charge current for an 800mAh Li-Ion battery. If a
typical 5V (non-current limited) input supply is available
then the peak power dissipation inside the part can
exceed 1W.
MN1
2k
1k
4065 F03
Figure 3. Combining Wall Adapter and USB Power
Now consider the same scenario, but with a 5V input
supply with a 600mA current limit. To take advantage of
the supply, it is necessary to program the LTC4065 to
chargeatacurrentabove600mA.AssumethattheLTC4065
is programmed for 650mA (i.e., RPROG = 1.54k) to ensure
thatparttolerancesmaintainaprogrammedcurrenthigher
Stability Considerations
The LTC4065/LTC4065A contain two control loops: con-
stant-voltage and constant-current. The constant-voltage
loop is stable without any compensation when a battery is
connected with low impedance leads. Excessive lead
4065fb
13
LTC4065/LTC4065A
W U U
U
APPLICATIO S I FOR ATIO
Power Dissipation
length, 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.
The conditions that cause the LTC4065/LTC4065A to
reduce charge current through thermal feedback can be
approximated by considering the power dissipated in the
IC. For high charge currents, the LTC4065/LTC4065A
power dissipation is approximately:
High value capacitors with very low ESR (especially ce-
ramic) may reduce the constant-voltage loop phase mar-
gin. 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.
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. It is not necessary to perform any worst-case
power dissipation scenarios because the LTC4065 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:
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. Because of the additional pole
created by the PROG pin capacitance, capacitance on this
pin must 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, addi-
tional capacitance on this node reduces the maximum
allowedprogramresistor. ThepolefrequencyatthePROG
pin should be kept above 100kHz. Therefore, if the PROG
pin is loaded with a capacitance, CPROG, the following
equation should be used to calculate the maximum resis-
TA = 115°C – PD • θJA
TA = 115°C – (VCC – VBAT) • IBAT • θJA
Example:ConsideranLTC4065/LTC4065Aoperatingfrom
a 5V wall adapter providing 750mA to a 3.6V Li-Ion
battery. The ambient temperature above which the
LTC4065/LTC4065Awillbegintoreducethe750mAcharge
current is approximately:
tance value for RPROG
:
1
RPROG
≤
2π •105 •CPROG
TA = 115°C – (5V – 3.6V) • (750mA) • 60°C/W
TA = 115°C – 1.05W • 60°C/W = 115°C – 63°C
TA = 52°C
Average, rather than instantaneous, battery 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 4. A 10K resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
The LTC4065/LTC4065A can be used above 70°C, but the
charge current will be reduced from 750mA. The approxi-
mate current at a given ambient temperature can be
calculated:
115°C – TA
IBAT
=
V – V
• θ
CC
BAT
JA
Using the previous example with an ambient temperature
of 73°C, the charge current will be reduced to approxi-
mately:
LTC4065
PROG
GND
CHARGE
10k
CURRENT
MONITOR
CIRCUITRY
R
C
FILTER
PROG
115°C –73°C
42°C
IBAT
=
=
= 500mA
4065 F04
5V –3.6V •60°C/W 84°C/A
Figure 4. Isolating Capacitive Load on the PROG Pin and Filtering
4065fb
14
LTC4065/LTC4065A
W U U
APPLICATIO S I FOR ATIO
U
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in the
Programming Charge Current section.
backside of the package and the copper board will result
in thermal resistances far greater than 60°C/W. As an
example, a correctly soldered LTC4065/LTC4065A can
deliver over 750mA to a battery from a 5V supply at room
temperature. Without a backside thermal connection, this
number could drop to less than 500mA.
It is important to remember that LTC4065/LTC4065A
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
approximately 115°C.
V
CC Bypass Capacitor
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 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.
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 LTC4065/LTC4065A package is soldered
to the PC board ground. Correctly soldered to a 2500mm2
double-sided 1 oz. copper board the LTC4065/LTC4065A
hasathermalresistanceofapproximately60°C/W. Failure
to make thermal contact between the Exposed Pad on the
U
PACKAGE DESCRIPTIO
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1703)
R = 0.115
TYP
0.38 ± 0.05
4
6
0.56 ± 0.05
(2 SIDES)
0.675 ±0.05
2.50 ±0.05
1.15 ±0.05
2.00 ±0.10
(4 SIDES)
0.61 ±0.05
(2 SIDES)
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
4065fb
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
LTC4065/LTC4065A
RELATED PARTS
PART NUMBER
Battery Chargers
LTC1734
DESCRIPTION
COMMENTS
Lithium-Ion Linear Battery Charger in ThinSOTTM
Lithium-Ion Linear Battery Charger in ThinSOT
Switch Mode Lithium-Ion Battery Charger
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
LTC1734L
Low Current Version of LTC1734, 50mA ≤ I
≤ 180mA
CHRG
LTC4002
Standalone, 4.7V ≤ V ≤ 24V, 500kHz Frequency, 3 Hour Charge
Termination
IN
LTC4050
Lithium-Ion Linear Battery Charger Controller
Features Preset Voltages, C/10 Charger Detection and Programmable
Timer, Input Power Good Indication, Thermistor Interface
LTC4052
LTC4053
Monolithic Lithium-Ion Battery Pulse Charger
No Blocking Diode or External Power FET Required, ≤1.5A Charge Current
USB Compatible Monolithic Li-Ion Battery Charger
Standalone Charger with Programmable Timer, Up to 1.25A Charge
Current
LTC4054
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
LTC4057
LTC4058
LTC4059
Lithium-Ion Linear Battery Charger
Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package
Standalone 950mA Lithium-Ion Charger in DFN
900mA Linear Lithium-Ion Battery Charger
C/10 Charge Termination, Battery Kelvin Sensing, ±7% Charge Accuracy
2mm × 2mm DFN Package, Thermal Regulation, Charge Current Monitor
Output
LTC4059A
900mA Linear Lithium-Ion Battery Charger
2mm × 2mm DFN Package, Thermal Regulation, Charge Current Monitor
Output, 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
Standalone Linear Li-Ion Battery Charger with
Micropower Comparator
4.2V, ±0.35% Float Voltage, Up to 1A Charge Current, 3mm × 3mm DFN
LTC4063
Li-Ion Charger with Linear Regulator
Low Loss PowerPathTM Controller in ThinSOT
Up to 1A Charge Current, 100mA, 125mV LDO, 3mm × 3mm DFN
LTC4411/LTC4412
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
Power Management
LTC3405/LTC3405A 300mA (I ), 1.5MHz, Synchronous Step-Down
95% Efficiency, V : 2.7V to 6V, V
ThinSOT Package
= 0.8V, I = 20µA, I < 1µA,
OUT Q SD
OUT
IN
DC/DC Converter
LTC3406/LTC3406A 600mA (I ), 1.5MHz, Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
ThinSOT Package
= 0.6V, I = 20µA, I < 1µA,
Q SD
OUT
IN
OUT
OUT
OUT
DC/DC Converter
LTC3411
LTC3440
LTC4413
1.25A (I ), 4MHz, Synchronous Step-Down
DC/DC Converter
95% Efficiency, V : 2.5V to 5.5V, V
= 0.8V, I = 60µA, I < 1µA,
Q SD
OUT
IN
MS Package
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
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.
4065fb
LT 0406 REV B • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005
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