LTC1734
Lithium-Ion Linear Battery
Charger in ThinSOT
FeaTures
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DescripTion
The
LTC
®
1734
is a low cost, single cell, constant-current/
constant-voltage Li-Ion battery charger controller. When
combined with a few external components, the TSOT-23
package forms a very small, low cost charger for single
cell lithium-ion batteries.
The LTC1734 is available in 4.1V and 4.2V versions with
1% accuracy. Constant current is programmed using a
single external resistor between the PROG pin and ground.
Manual shutdown is accomplished by floating the program
resistor while removing input power automatically puts
the LTC1734 into a sleep mode. Both the shutdown and
sleep modes drain near zero current from the battery.
Charge current can be monitored via the voltage on the
PROG pin allowing a microcontroller or ADC to read the
current and determine when to terminate the charge cycle.
The output driver is both current limited and thermally
protected to prevent the LTC1734 from operating outside
of safe limits. No external blocking diode is required.
The LTC1734 can also function as a general purpose current
source or as a current source for charging nickel-cadmium
(NiCd) and nickel-metal-hydride (NiMH) batteries using
external termination.
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Low Profile (1mm) ThinSOT™ Package
No Blocking Diode Required
No Sense Resistor Required
1% Accurate Preset Voltages: 4.1V or 4.2V
Charge Current Monitor Output
for Charge Termination
Programmable Charge Current: 200mA to 700mA
Automatic Sleep Mode with Input Supply Removal
Manual Shutdown
Negligible Battery Drain Current in Shutdown
Undervoltage Lockout
Self Protection for Overcurrent/Overtemperature
applicaTions
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Cellular Telephones
Handheld Computers
Digital Cameras
Charging Docks and Cradles
Low Cost and Small Size Chargers
Programmable Current Sources
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
Typical applicaTion
300mA Li-Ion Battery Charger
5V
V
BAT
(V)
V
IN
5V
3
1µF
2
4
R
PROG
5k
V
CC
I
SENSE
1
FMMT549
I
BAT
= 300mA
10µF
V
BAT
4V
PROG Pin Indicates Charge Status
LTC1734
6
GND
DRIVE
PROG
BAT
5
3V
CONSTANT
CURRENT
V
PROG
CONSTANT
VOLTAGE
+
SINGLE
Li-Ion
BATTERY
1734 TA01
2V
V
PROG
(V)
1.5V
1V
0V
CHARGING
BEGINS
CHARGING
COMPLETE
1734 TA01b
1734fa
For more information
www.linear.com/LTC1734
1
LTC1734
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
I
SENSE
1
GND 2
V
CC
3
6 DRIVE
5 BAT
4 PROG
Supply Voltage (V
CC
) ................................. – 0.3V to 9V
Input Voltage (BAT, PROG)........... –0.3V to (V
CC
+ 0.3V)
Output Voltage (DRIVE) ............... –0.3V to (V
CC
+ 0.3V)
Output Current (I
SENSE
).................................... –900mA
Short-Circuit Duration (DRIVE) ....................... Indefinite
Junction Temperature .......................................... 125°C
Operating Ambient Temperature Range
(Note 2) ...............................................–40°C to 85°C
Operating Junction Temperature (Note 2) ............. 100°C
Storage Temperature Range ..................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 230°C/W
orDer inForMaTion
LEAD FREE FINISH
LTC1734ES6-4.1#PBF
LTC1734ES6-4.2#PBF
TAPE AND REEL
LTC1734ES6-4.1#TRPBF
LTC1734ES6-4.2#TRPBF
PART MARKING
LTHD
LTRG
PACKAGE DESCRIPTION
6-Lead Plastic SOT-23
6-Lead Plastic SOT-23
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 nonstandard 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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, GND = 0V and V
BAT
is equal to the float voltage unless
otherwise noted. All current into a pin is positive and current out of a pin is negative. All voltages are referenced to GND, unless
otherwise specified.
SYMBOL
V
CC
Supply
V
CC
I
CC
I
SHDN
I
BMS
I
BSL
V
UVLOI
V
UVLOD
V
UVHYS
Operating Supply Range (Note 5)
Quiescent V
CC
Pin Supply Current
V
CC
Pin Supply Current in Manual Shutdown
Battery Drain Current in Manual Shutdown
Battery Drain Current in Sleep Mode (Note 4)
Undervoltage Lockout Exit Threshold
Undervoltage Lockout Entry Threshold
Undervoltage Lockout Hysteresis
V
BAT
= 5V, (Forces I
DRIVE
= I
BAT
= 0),
I
PROG
= 200µA,(7500Ω from PROG to GND)
PROG Pin Open
PROG Pin Open (Note 3)
V
CC
= 0V
V
CC
Increasing
V
CC
Decreasing
V
CC
Decreasing
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elecTrical characTerisTics
PARAMETER
CONDITIONS
MIN
4.55
TYP
MAX
8
UNITS
V
µA
µA
µA
µA
V
V
mV
670
450
–1
–1
4.45
4.30
0
0
4.56
4.41
150
1150
900
1
1
4.68
4.53
2
1734fa
For more information
www.linear.com/LTC1734
LTC1734
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, GND = 0V and V
BAT
is equal to the float voltage unless
otherwise noted. All current into a pin is positive and current out of a pin is negative. All voltages are referenced to GND, unless
otherwise specified.
SYMBOL
V
BAT
I
BAT1
I
BAT2
V
CM1
V
CM2
I
DSINK
V
MSDT
V
MSHYS
I
PROGPU
Protection
I
DSHRT
Drive Output Short-Circuit Current Limit
V
DRIVE
= V
CC
●
elecTrical characTerisTics
PARAMETER
CONDITIONS
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MIN
4.059
4.158
155
620
0.045
TYP
4.10
4.20
200
700
0.15
MAX
4.141
4.242
240
770
0.28
UNITS
V
V
mA
mA
V
Charging Performance
Output Float Voltage in Constant Voltage Mode 4.1V Version, I
BAT
= 10mA, 4.55V ≤ V
CC
≤ 8V
4.2V Version, I
BAT
= 10mA, 4.55V ≤ V
CC
≤ 8V
Output Full-Scale Current When Programmed
for 200mA in Constant Current Mode
Output Full-Scale Current When Programmed
for 700mA in Constant Current Mode
Current Monitor Voltage on PROG Pin
R
PROG
= 7500Ω, 4.55V ≤ V
CC
≤ 8V,
Pass PNP Beta > 50
R
PROG
= 2143Ω, 4.55V ≤ V
CC
≤ 8V,
Pass PNP Beta > 50
I
BAT
= 10% of I
BAT1
, R
PROG
= 7500Ω,
4.55V ≤ V
CC
≤ 8V, Pass PNP Beta > 50,
0°C ≤ T
A
≤ 85°C
I
BAT
= 10% of I
BAT2
, R
PROG
= 2143Ω,
4.55V ≤ V
CC
≤ 8V, Pass PNP Beta > 50,
0°C ≤ T
A
≤ 85°C
V
DRIVE
= 3.5V
V
PROG
Increasing
V
PROG
Decreasing from V
MSDT
V
PROG
= 2.5V
–6
35
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Current Monitor Voltage on PROG Pin
0.10
0.15
0.20
V
Drive Output Current
Manual Shutdown Threshold
Manual Shutdown Hysteresis
Programming Pin Pull-Up Current
30
2.05
2.15
90
–3
65
–1.5
130
2.25
mA
V
mV
µA
mA
Charger Manual Control
●
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 LTC1734E is guaranteed to meet performance specifications
from 0°C to 70°C ambient temperature range and 0°C to 100°C junction
temperature range. Specifications over the – 40°C to 85°C operating
ambient temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
Assumes that the external PNP pass transistor has negligible B-C
reverse-leakage current when the collector is biased at 4.2V (V
BAT
) and the
base is biased at 5V (V
CC
).
Note 4:
Assumes that the external PNP pass transistor has negligible B-E
reverse-leakage current when the emitter is biased at 0V (V
CC
) and the
base is biased at 4.2V (V
BAT
).
Note 5:
The 4.68V maximum undervoltage lockout (UVLO) exit threshold
must first be exceeded before the minimum V
CC
specification applies.
Short duration drops below the minimum V
CC
specification of several
microseconds or less are ignored by the UVLO. If manual shutdown
is entered, then V
CC
must be higher than the 4.68V maximum UVLO
threshold before manual shutdown can be exited. When operating near
the minimum V
CC
, a suitable PNP transistor with a low saturation voltage
must be used.
1734fa
For more information
www.linear.com/LTC1734
3
LTC1734
Typical perForMance characTerisTics
Float Voltage vs Temperature
and Supply Voltage
4.21
I
BAT
= 10mA
PNP = FCX589
4.2V OPTION
FLOAT VOLTAGE (V)
4.201
Float Voltage vs I
BAT
V
CC
= 5V
T
A
= 25°C
PNP = FCX589
4.2V OPTION
R
PROG
= 2150
I
BAT1
(mA)
210
I
BAT1
vs Temperature
and Supply Voltage
R
PROG
= 7.5k
PNP = FCX589
FLOAT VOLTAGE (V)
4.20
V
CC
= 8V
V
CC
= 4.55V
4.200
200
V
CC
= 4.55V AND 8V
4.19
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
4.199
0
100
200
300 400
I
BAT
(mA)
500
600
700
190
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
1734 G01
1734 G02
1734 G03
I
BAT2
vs Temperature
and Supply Voltage
740
R
PROG
= 2.15k
PNP = FCX589
210
I
BAT1
vs V
BAT
V
CC
= 5V
T
A
= 25°C
R
PROG
= 7.5k
PNP = FCX589
I
BAT2
(mA)
750
I
BAT2
vs V
BAT
V
CC
= 5V
T
A
= 25°C
R
PROG
= 2.15k
PNP = FCX589
I
BAT2
(mA)
I
BAT1
(mA)
700
V
CC
= 4.55V AND 8V
200
BAT PIN MUST BE DISCONNECTED
AND GROUNDED TO FORCE
CC MODE IN THIS REGION
700
BAT PIN MUST BE DISCONNECTED
AND GROUNDED TO FORCE
CC MODE IN THIS REGION
660
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
190
0
1
3
2
V
BAT
(V)
4
5
1734 G05
650
0
1
3
2
V
BAT
(V)
4
5
1734 G06
1734 G04
Program Pin Pull-Up Current vs
Temperature and Supply Voltage
3.6
3.5
3.4
I
PROGPU
(A)
3.3
V
CC
= 4.55V
3.2
3.1
3.0
–50 –25
V
CC
= 8V
I
PROGPU
(A)
V
PROG
= 2.5V
3.6
Program Pin Pull-Up Current
vs V
PROG
V
CC
= 8V
T
A
= 25°C
1.6
Program Pin Voltage
vs Charge Current (200mA)
V
CC
= 5V
T = 25°C
1.4
A
R
PROG
= 7.5k
PNP = FCX589
1.2
V
PROG
(V)
1.0
0.8
0.6
0.4
0.2
LIMITS AT 25mV DUE TO
PROGRAMMING PIN PULL-UP
CURRENT (I
PROGPU
)
0
50
100
I
BAT1
(mA)
1635 G08
1734 F09
3.4
3.2
3.0
2.8
2.6
50
25
75
0
TEMPERATURE (°C)
100
125
2
3
4
5
V
PROG
(V)
6
7
8
0
150
200
1734 G07
4
1734fa
For more information
www.linear.com/LTC1734
LTC1734
Typical perForMance characTerisTics
Program Pin Voltage
vs Charge Current (700mA)
1.6
V
CC
= 5V
T = 25°C
1.4
A
R
PROG
= 2.15k
PNP = FCX589
1.2
V
PROG
(mV)
V
PROG
(V)
1.0
0.8
0.6
0.4
0.2
0
0
100
LIMITS AT 6mV DUE TO
PROGRAMMING PIN PULL-UP
CURRENT (I
PROGPU
)
200
300 400
I
BAT2
(mA)
500
600
700
140
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
140
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
160
Program Pin Voltage for I
BAT1
/10
vs Temperature and Supply Voltage
R
PROG
= 7.5k
PNP = FCX589
160
Program Pin Voltage for I
BAT2
/10
vs Temperature and Supply Voltage
R
PROG
= 2.15k
PNP = FCX589
150
V
CC
= 8V
V
CC
= 4.55V
V
PROG
(mV)
V
CC
= 8V
150
V
CC
= 4.55V
1734 G10
1734 G11
1734 G12
pin FuncTions
I
SENSE
(Pin 1):
Sense Node for Charge Current. Current
from V
CC
passes through the internal current sense resistor
and reappears at I
SENSE
to supply current to the external
PNP emitter. The PNP collector provides charge current
to the battery.
GND (Pin 2):
Ground. Provides a reference for the internal
voltage regulator and a return for all internal circuits. When
in the constant voltage mode, the LTC1734 will precisely
regulate the voltage between the BAT and GND pins. The
battery ground should connect close to the GND pin to
avoid voltage drop errors.
V
CC
(Pin 3):
Positive Input Supply Voltage. This pin sup-
plies power to the internal control circuitry and external
PNP transistor through the internal current sense resistor.
This pin should be bypassed to ground with a capacitor
in the range of 1µF to 10µF.
PROG (Pin 4):
Charge Current Programming, Charge Cur-
rent Monitor and Manual Shutdown Pin. Provides a virtual
reference voltage of 1.5V for an external resistor (R
PROG
)
tied between this pin and ground that programs the bat-
tery charge current when the charger is in the constant
current mode. The typical charge current will be 1000
times greater than the current through this resistor (I
BAT
= 1500/R
PROG
). This pin also allows for the charge current
to be monitored. The voltage on this pin is proportional
to the charge current where 1.5V corresponds to the full
programmed current. Floating this pin allows an internal
current source to pull the pin voltage above the shutdown
threshold voltage. Because this pin is in a signal path,
excessive capacitive loading can cause AC instability.
See the Applications Information section for more details.
BAT (Pin 5):
Battery Voltage Sense Input. A precision
internal resistor divider sets the final float voltage on this
pin. This divider is disconnected in the manual shutdown
or sleep mode. When charging, approximately 34µA
flows into the BAT pin. To minimize float voltage errors,
avoid excessive resistance between the battery and the
BAT pin. For dynamically stable operation, this pin usu-
ally requires a minimum bypass capacitance to ground
of 5µF to frequency compensate for the high frequency
inductive effects of the battery and wiring.
DRIVE (Pin 6):
Base Drive Output for the External PNP
Pass Transistor. Provides a controlled sink current that
drives the base of the PNP. This pin has current limiting
protection for the LTC1734.
1734fa
For more information
www.linear.com/LTC1734
5
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