LTC4057-4.2
1
4057f
■
Programmable Charge Current up to 800mA
■
No External MOSFET, Sense Resistor or Blocking
Diode Required
■
Constant-Current/Constant-Voltage Operation with
Thermal Regulation Maximizes Charge Rate
Without Risk of Overheating*
■
Charges Single Cell Li-Ion Batteries Directly from
USB Port
■
Preset 4.2V Charge Voltage with ±1% Accuracy
■
Current Monitor Pin for Charge Termination
■
25µA Supply Current in Shutdown Mode
■
Low Battery Charge Conditioning (Trickle Charging)
■
Soft-Start Limits Inrush Current
■
Available in a Low Profile (1mm) SOT-23 Package
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
Linear Li-Ion Battery
Charger with Thermal
Regulation in ThinSOT
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Wireless PDAs
■
Cellular Phones
■
Portable Electronics
The LTC
®
4057 is a constant-current/constant-voltage lin-
ear charger for single-cell lithium-ion batteries. Its
ThinSOT
TM
package and low external component count
make the LTC4057 especially well suited for portable
applications. Furthermore, the LTC4057 is specifically
designed to work within USB power specifications.
No external sense resistor is needed and no blocking diode
is required due to the internal MOSFET architecture.
Thermal feedback prevents overheating by regulating the
charge current to limit the die temperature during high
power operation or high ambient temperature conditions.
The charge voltage is preset at 4.2V and the charge current
can be programmed externally with a single resistor.
When the input supply (wall adapter or USB supply) is
removed, the LTC4057 automatically enters a low current
state, dropping the battery drain current to less than 2µA.
With power applied, the LTC4057 can be put into shut-
down mode, reducing the supply current to 25µA.
For the standalone version (on-board charge termination)
of the LTC4057, refer to the LTC4054.
Charge Curve (750mAh Battery)
LTC4057-4.2
PROG
GND
1.65k
4057 TA01a
SHDN
BAT
V
CC
ON OFF
1µF
V
IN
5V 600mA
1-CELL
4.2V Li-Ion
BATTERY
+
4
1
2
5
3
ThinSOT is a trademark of Linear Technology Corporation.
*U.S. Patent No. 6522118
TIME (HOURS)
0
CHARGE CURRENT (mA)
BATTERY VOLTAGE (V)
700
600
500
400
300
200
100
0
4.75
4.5
4.25
4.0
3.75
3.5
3.25
3.0
4057 TA01b
0.50.25 0.75 1.0 1.25 1.5 1.75 2.0 2.25
CONSTANT
CURRENT
CONSTANT
POWER CONSTANT
VOLTAGE
V
CC
= 5V
θ
JA
= 130°C/W
R
PROG
= 1.65kΩ
T
A
= 25°C
LTC4057-4.2
2
4057f
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
CC
Input Supply Voltage ●4.25 6.5 V
I
CC
Input Supply Current I
BAT
= 0mA, R
PROG
= 2k ●200 600 µA
Shutdown Mode (SHDN = 0V, ●50 µA
V
CC
< V
BAT
, or V
CC
< V
UV
)
V
FLOAT
Regulated Output (Float) Voltage I
BAT
= 40mA, 0°C < T
A
< 85°C 4.158 4.2 4.242 V
I
BAT
BAT Pin Charge Current R
PROG
= 10k; Current Mode ●93 100 107 mA
R
PROG
= 2k; Current Mode ●465 500 535 mA
Shutdown Mode (SHDN = 0V) ±1±2µA
Sleep Mode (V
CC
= 0V) ±1±2µA
I
TRIKL
Trickle Charge Current V
BAT
< 2.9V; R
PROG
= 2k (I
CHG
= 500mA) ●20 50 70 mA
V
TRIKL
Trickle Charge Threshold Voltage R
PROG
= 10k; V
BAT
Rising 2.8 2.9 3.0 V
Hysteresis 60 80 110 mV
V
UV
V
CC
Undervoltage Lockout Voltage From Low to High ●3.7 3.8 3.9 V
Hysteresis ●150 200 300 mV
V
ASD
V
CC
- V
BAT
Lockout Threshold Voltage V
CC
from Low to High 70 100 150 mV
V
CC
from High to Low 5 30 70 mV
V
PROG
PROG Pin Voltage R
PROG
= 10k; Current Mode ●0.93 1.0 1.07 V
V
SHDN-IL
SHDN Pin Input Low Voltage 0.4 0.65 V
V
SHDN-IH
SHDN Pin Input High Voltage 0.65 1.0 V
I
SHDN
SHDN Pin Input Current V
SHDN
= 5V ●515 µA
T
LIM
Junction Temperature in 120 °C
Constant-Temperature Mode
R
ON
Power FET “ON” Resistance 600 mΩ
(Between V
CC
and BAT)
t
SS
Soft-Start Time I
BAT
= 0 to I
BAT
= 1000V/R
PROG
100 µs
(Note 1)
Input Supply Voltage (V
CC
) ........................–0.3V to 10V
PROG.............................................. –0.3V to V
CC
+ 0.3V
BAT..............................................................–0.3V to 7V
SHDN.........................................................–0.3V to 10V
BAT Short Circuit Duration ...........................Continuous
BAT Pin Current .................................................. 800mA
PROG Pin Current................................................ 800µA
Junction Temperature........................................... 125°C
Operating Ambient Temperature Range
(Note 2) .............................................. –40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
S5 PART
MARKING
T
JMAX
= 125°C, (θ
JA
= 100°C/W TO 150°C/W
DEPENDING ON PC BOARD LAYOUT)
(NOTE 3)
LTAEW
LTC4057ES5-4.2
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V
Consult LTC Marketing for parts specified with wider operating temperature ranges.
5 PROG
4 V
CC
SHDN 1
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC SOT-23
GND 2
BAT 3
LTC4057-4.2
3
4057f
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC4057 is guaranteed to meet performance specifications from
0°C to 70°C. Specifications over the –40°C to 85°C operating temperature
ELECTRICAL CHARACTERISTICS
range are assured by design, characterization and correlation with statistical
process controls.
Note 3: See Thermal Considerations.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
VPROG (V)
VCC (V)
4.0
VPROG (V)
1.015
1.010
1.005
1.000
0.995
0.990
0.985 4.5 5.0 5.5 6.0
4057 G01
6.5 7.0
TEMPERATURE (°C)
–50 –25 0 5025 75 100
4057 G02
1.0100
1.0075
1.0050
1.0025
1.0000
0.9975
0.9950
0.9925
0.9900
VPROG (V)
0
IBAT (mA)
600
500
400
300
200
100
00.25 0.50 0.75 1.00
4057 G03
1.25
VCC = 5V
VBAT = 4V
TA = 25°C
RPROG = 10k
VCC = 5V
VBAT = 4V
RPROG = 10k
VCC = 5V
TA = 25°C
RPROG = 2k
VFLOAT (V)
VFLOAT (V)
4057 G04
4.26
4.24
4.22
4.20
4.18
4.16
4.14
4.12
4.10
IBAT (mA)
0100 200 300 400 500 700600
VCC (V)
4.0
4.215
4.210
4.205
4.200
4.195
4.190
4.185 4.5 5.0 5.5 6.0
4057 G06
6.5 7.0
VCC = 5V
TA = 25°C
RPROG = 1.25k
TA = 25°C
RPROG = 10k
TEMPERATURE (°C)
–50
VFLOAT (V)
100
050–25 25 75
4.220
4.215
4.210
4.205
4.200
4.195
4.190
4.185
4.180
4057 G05
VCC = 5V
RPROG = 10k
PROG Pin Voltage vs Supply
Voltage (Constant Current Mode) PROG Pin Voltage vs Temperature
(Constant Current Mode)
Charge Current vs PROG Pin
Voltage
Regulated Output (Float) Voltage
vs Charge Current Regulated Output (Float) Voltage
vs Temperature
Regulated Output (Float) Voltage
vs Supply Voltage
LTC4057-4.2
4
4057f
TYPICAL PERFOR A CE CHARACTERISTICS
UW
SHDN Threshold Voltage vs
Temperature and Supply Voltage Trickle Charge Current vs
Temperature
Trickle Charge Current vs Supply
Voltage
TEMPERATURE (°C)
–50 –25 0 25 50 75 100
V
TRIKL
(V)
4057 G10
3.000
2.975
2.950
2.925
2.900
2.875
2.850
2.825
2.800
V
BAT
(V)
2.7 3.0
I
BAT
(mA)
I
BAT
(mA)
3.3 3.93.6 4.2 4.5
4057 G11
600
500
400
300
200
100
0
V
CC
(V)
4.0
600
500
400
300
200
100
04.5 5.0 5.5 6.0
4057 G12
6.5 7.0
V
BAT
= 4V
T
A
= 25°C
θ
JA
= 125°C/W
V
CC
= 5V
θ
JA
= 125°C/W
R
PROG
= 2k
V
CC
= 5V
R
PROG
= 10k
R
PROG
= 10k
R
PROG
= 2k
T
A
= 40°C
T
A
= 25°C
T
A
= 0°C
TEMPERATURE (°C)
–50
V
SHDN
(V)
1.0
0.9
0.8
0.7
0.6
0.5
0.4 –25 02550
4057 G07
75 100
TEMPERATURE (°C)
–50 –25 0 25 50 75 100
I
TRIKL
(mA)
I
TRIKL
(mA)
60
50
40
30
20
10
0
4057 G08
V
CC
(V)
4.0 4.5 5.0 5.5 6.0
4057 G09
6.5 7.0
V
CC
= 5V
V
BAT
= 2.5V
R
PROG
= 2k
R
PROG
= 10k
V
CC
= 6.5V
V
CC
= 4.2V
60
50
40
30
20
10
0
V
BAT
= 2.5V
T
A
= 25°C
R
PROG
= 2k
R
PROG
= 10k
I
BAT
(mA)
600
500
400
300
200
100
0
AMBIENT TEMPERATURE (°C)
–50 25 75
4057 G13
–25 0 50 100 125
TEMPERATURE (°C)
–50
R
DS(ON)
(mΩ)
700
650
600
550
500
450
400 25 75
4057 G14
–25 0 50 100 125
V
CC
= 5V
V
BAT
= 4V
θ
JA
= 80°C/W
V
CC
= 4.2V
V
BAT
= 4V
R
PROG
= 2k
R
PROG
= 10k
R
PROG
= 2k
ONSET OF
THERMAL
REGULATION
Trickle Charge Threshold vs
Temperature Charge Current vs Battery Voltage Charge Current vs Supply Voltage
Charge Current vs Ambient
Temperature Power FET “ON” Resistance vs
Temperature
LTC4057-4.2
5
4057f
UU
U
PI FU CTIO S
SHDN (Pin 1): Shutdown Input. Pulling this pin low puts
the LTC4057 in shutdown mode, thus stopping the charge
current. In shutdown mode, the input supply current
drops to 25µA and the battery drain current drops to less
than 2µA. This pin has an internal 1MΩ resistor to GND.
GND (Pin 2): Ground.
BAT (Pin 3): Charge Current Output. Provides charge
current to the battery and regulates the final float voltage
to 4.2V. An internal precision resistor divider from this pin
sets the float voltage and is disconnected in shutdown
mode.
V
CC
(Pin 4): Positive Input Supply Voltage. Provides
power to the charger. V
CC
can range from 4.25V to 6.5V
and should be bypassed with at least a 1µF capacitor.
When V
CC
drops to within 30mV of the BAT pin voltage, the
LTC4057 enters shutdown mode, dropping I
BAT
to less
than 2µA.
PROG (Pin 5): Charge Current Program and Charge Cur-
rent Monitor Pin. The charge current is programmed by
connecting a 1% resistor, R
PROG
, to ground. When charg-
ing in constant-current mode, this pin servos to 1V. In all
modes, the voltage on this pin can be used to measure the
charge current using the following formula:
I
BAT
= (V
PROG
/R
PROG
) • 1000
This pin is clamped to approximately 2.4V. Driving this pin
to voltages beyond the clamp voltage will draw currents as
high as 1.5mA.
BLOCK DIAGRA
W
3
4
–
+
–
+
–
+
–+
T
A
REF
1.21V
120°C
1
5 2
2.9V TO BAT
C1
CA
V
CC
T
DIE
PROG
R
PROG
SHDN
GND
R3
R4
R5
R1
R2
BAT
1V
0.1V
1×1000×
MA
VA
4-57 BD
5µA
+1
1MΩ
LTC4057-4.2
6
4057f
The LTC4057 is a single-cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 800mA of charge current (using a good
thermal PC board layout) with a final float voltage accuracy
of ±1%. The LTC4057 includes an internal P-channel
power MOSFET and thermal regulation circuitry. No block-
ing diode or external current sense resistor is required and
the LTC4057 is capable of operating from a USB power
source.
Normal Charge
Charging begins when SHDN is high, the voltage at the V
CC
pin rises above the UVLO threshold level and a program
resistor is connected from the PROG pin to ground. If the
BAT pin voltage is below 2.9V, the charger enters trickle-
charge mode. In this mode, the LTC4057 supplies ap-
proximately 1/10 the programmed charge current to bring
the battery voltage up to a safe level for full current
charging.
When the BAT pin voltage rises above 2.9V, the charger
enters constant-current mode, where the programmed
charge current is supplied to the battery. When the BAT pin
approaches the final float voltage (4.2V), the LTC4057
enters constant-voltage mode, and the charge current
begins to decrease.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The charge current is 1000
times the current out of the PROG pin. The program
resistor and the charge current are calculated using the
following equations:
RV
IIV
R
PROG CHG CHG PROG
==
1000 1000
,
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:
IV
R
BAT PROG
PROG
=•1000
Thermal Limiting
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise
above a preset value of approximately 120°C. This feature
protects the LTC4057 from excessive temperature and
allows the user to push the limits of the power handling
capability of a given circuit board without risk of damaging
the LTC4057. The charge current can be set according to
typical (not worst-case) ambient temperature with the
assurance that the charger will automatically reduce the
current in worst-case conditions. ThinSOT power consid-
erations are discussed further in the Applications Informa-
tion section.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input
voltage and keeps the charger in shutdown mode until V
CC
rises above the undervoltage lockout threshold. The UVLO
circuit has a built-in hysteresis of 200mV. Furthermore, to
protect against reverse current in the power MOSFET, the
UVLO circuit keeps the charger in shutdown mode if V
CC
falls to within 30mV of the battery voltage. If the UVLO
comparator is tripped, the charger will not come out of
shutdown mode until V
CC
rises 100mV above the battery
voltage.
Shutdown Mode
The LTC4057 can also be put into shutdown mode at any
time by applying logic “low” to the SHDN pin (V
SHDN
<
0.4V). This reduces the battery drain current to less than
2µA and the input supply current to less than 50µA.
Charging will resume when applying a logic “high” to the
SHDN pin (V
SHDN
> 1V).
OPERATIO
U
LTC4057-4.2
7
4057f
Stability Considerations
The constant-voltage mode feedback loop is stable with-
out an output capacitor provided a battery is connected to
the charge output. When an output capacitor is used,
especially high value low ESR ceramic types, it is recom-
mended that a 1Ω resistor be placed in series with the
capacitor to stabilize the voltage loop. The loop stability is
determined by the bypass capacitor as well as the effective
series resistance of the battery.
When the battery is disconnected and the LTC4057 is still
powered, the voltage regulation loop should be compen-
sated by placing a capacitor greater than 1µF from the BAT
pin to ground with a 1Ω to 2Ω resistor in series with this
capacitor. Alternatively, powering down the LTC4057 or
placing it into shutdown mode when the battery is discon-
nected avoids this problem.
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. The constant-current mode stability
is affected by the impedance at the PROG pin. With no
additional capacitance on the PROG pin, the charger is
stable with program resistor values as high as 20k. How-
ever, additional capacitance on this node reduces the
maximum allowed program resistor value. The pole fre-
quency at the PROG pin should be kept above 100kHz.
Therefore, if the PROG pin is loaded with a capacitance,
C
PROG
, the following equation can be used to calculate the
maximum resistance value for R
PROG
:
RC
PROG
PROG
≤1
210
5
π••
Average, rather than instantaneous, battery current may
be 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
battery current as shown in Figure 1. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
APPLICATIO S I FOR ATIO
WUUU
Power Dissipation
The conditions that cause the LTC4057 to reduce charge
current through thermal feedback can be approximated by
considering the power dissipated in the IC. Nearly all of
this power dissipation is generated by the internal MOSFET.
This is calculated to be approximately:
P
D
= (V
CC
– V
BAT
) • I
BAT
where P
D
is the power dissipated, V
CC
is the input supply
voltage, V
BAT
is the battery voltage, and I
BAT
is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
T
A
= 120°C – P
D
θ
JA
T
A
= 120°C – (V
CC
– V
BAT
) • I
BAT
• θ
JA
Example: An LTC4057 operating from a 4.5V USB supply
is programmed to supply 600mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.7V. Assuming
θ
JA
is 150°C/W (see Board Layout Considerations), the
ambient temperature at which the LTC4057 will begin to
reduce the charge current is approximately:
T
A
= 120°C – (4.5V – 3.7V) • (600mA) • 150°C/W
T
A
= 120°C – 0.48W • 150°C/W = 120°C – 72°C
T
A
= 48°C
The LTC4057 can be used above 48°C ambient, but the
charge current will be reduced from 600mA. The approxi-
mate current at a given ambient temperature can be
approximated by:
ICT
VV
BAT A
CC BAT JA
=°
−
120 –
()•θ
LTC4057-4.2
PROG
GND
10k
R
PROG
C
FILTER
CHARGE CURRENT
MONITOR CIRCUITRY
4057 F01
Figure 1. Isolating Capacitive Load on PROG Pin and Filtering
LTC4057-4.2
8
4057f
Using the previous example with an ambient temperature
of 60°C, the charge current will be reduced to approxi-
mately:
ICC
VV CW
C
CA
ImA
BAT
BAT
=°°
°=°
°
=
120 60
45 37 150
60
120
500
–
(. – . )• / /
Moreover, when thermal feedback reduces the charge
current, the voltage at the PROG pin is also reduced
proportionally as discussed in the Operation section.
It is important to remember that LTC4057 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
120°C.
Thermal Considerations
Because of the small size of the ThinSOT package, it is very
important to use a good thermal PC board layout to
maximize the available charge current. The thermal path
for the heat generated by the IC is from the die to the
copper lead frame, through the package leads, (especially
the ground lead) to the PC board copper. The PC board
copper is the heat sink. The footprint copper pads should
be as wide as possible and expand out to larger copper
areas to spread and dissipate the heat to the surrounding
ambient. Feedthrough vias to inner or backside copper
layers are also useful in improving the overall thermal
performance of the charger. Other heat sources on the
board, not related to the charger, must also be considered
when designing a PC board layout because they will affect
overall temperature rise and the maximum charge current.
Table 1 lists thermal resistance for several different board
sizes and copper areas. All measurements were taken in
still air on 3/32" FR-4 board with one ounce copper.
Table 1. Measured Thermal Resistance
THERMAL
COPPER AREA RESISTANCE
BOARD JUNCTION-TO-
TOPSIDE* BACKSIDE AREA AMBIENT
2500mm
2
2500mm
2
2500mm
2
125°C/W
1000mm
2
2500mm
2
2500mm
2
125°C/W
225mm
2
2500mm
2
2500mm
2
130°C/W
100mm
2
2500mm
2
2500mm
2
135°C/W
50mm
2
2500mm
2
2500mm
2
150°C/W
*Device is mounted on topside.
Increasing Thermal Regulation Current
Reducing the voltage drop across the internal MOSFET
can significantly decrease the power dissipation in the IC.
This has the effect of increasing the current delivered to
the battery during thermal regulation. One method is by
dissipating some of the power through an external compo-
nent, such as a resistor or diode.
Example: An LTC4057-4.2 operating from a 5V wall adapter
is programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.75V. Assum-
ing θ
JA
is 125°C/W, the approximate charge current at an
ambient temperature of 25°C is:
ICC
VVCWmA
BAT
=°°
°=
120 25
5 3 75 125 608
–
(–. )• /
By dropping voltage across a resistor in series with a 5V
wall adapter (shown in Figure 2), the on-chip power
dissipation can be decreased, thus increasing the ther-
mally regulated charge current.
ICC
VIR V
BAT S BAT CC BAT JA
=°°120 25–
(– – )•θ
APPLICATIO S I FOR ATIO
WUUU
LTC4057-4.2
9
4057f
Figure 2. A Circuit to Maximize Thermal Mode Charge Current
V
CC
R
PROG
R
CC
Li-Ion
CELL
405742 F02
LTC4057-4.2
1µF
V
S
BAT
PROG
GND
+
4
3
5
2
Solving for I
BAT
using the quadratic formula
1
.
I
VV VV RCT
R
BAT
S BAT S BAT CC A
JA
CC
=
°
(– )– (– ) (–)
24 120
2
θ
Using R
CC
= 0.25Ω, V
S
= 5V, V
BAT
= 3.75V, T
A
= 25°C and
θ
JA
= 125°C/W, we can calculate the thermally
regulated charge current to be:
I
BAT
= 708.4mA
Note 1: Large values of R
CC
will result in no solution for I
BAT
. This indicates that the LTC4057 will
not generate enough heat to require thermal regulation.
While this application delivers more energy to the battery
and reduces charge time in thermal mode, it may actually
lengthen charge time in voltage mode if V
CC
becomes low
enough to put the LTC4057 into dropout. Figure 3 shows
how this circuit can result in dropout as R
CC
becomes
large.
This technique works best when R
CC
values are minimized
to keep component size small and avoid dropout. Remem-
ber to choose a resistor with adequate power handling
capability.
R
CC
(Ω)
0
CHARGE CURRENT (mA)
1000
800
600
400
200
00.5 1.0 1.25
405442 F03
0.25 0.75 1.5 1.75
CONSTANT
CURRENT
V
BAT
= 3.75V
T
A
= 25°C
θ
JA
= 125°C/W
R
PROG
= 1.25kΩ
THERMAL
MODE
DROPOUT
V
S
= 5.25V
V
S
= 5.5V
V
S
= 5V
Figure 3. Charge Current vs RCC
APPLICATIO S I FOR ATIO
WUUU
LTC4057-4.2
10
4057f
V
CC
Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-
layer ceramic capacitors. Because of the self resonant and
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. Adding a 1.5Ω resistor in series
with an X5R ceramic capacitor will minimize start-up
voltage transients. For more information, refer to Applica-
tion Note 88.
Charge Current Soft-Start
The LTC4057 includes a soft-start circuit to minimize the
inrush current at the start of a charge cycle. When charg-
ing begins, the charge current ramps from zero to the full-
scale current over a period of approximately 100µs. This
has the effect of minimizing the transient current load on
the power supply during startup.
APPLICATIO S I FOR ATIO
WUUU
LTC4057-4.2
11
4057f
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
PACKAGE DESCRIPTIO
U
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-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3) S5 TSOT-23 0302
PIN ONE
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX 0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
LTC4057-4.2
12
4057f
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
LT/TP 0503 1K • PRINTED IN USA
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TYPICAL APPLICATIO S
U
800mA Li-Ion Charger with
External Power Dissipation Basic Li-Ion Battery Charger with
Reverse Polarity Input Protection
V
CC
0.25Ω
1µFLTC4057-4.2
BAT
800mA
4057 TA02
PROGSHDN
1.25k
V
IN
= 5V
GND
+
4
2
3
2
5
ON OFF
V
CC
1µF
LTC4057-4.2
BAT
4057 TA03
PROG
2k
5V WALL
ADAPTER
GND
43
2
5
+
500mA
SHDN
2
ON OFF
