LTC4058XEDD-4.2 [Linear]
Standalone Linear Li-Ion Battery Charger with Thermal Regulation in DFN; 独立线性锂离子电池充电器， DFN热调节
| 型号： | LTC4058XEDD-4.2 |
| 厂家： | 
Linear |
| 描述： | Standalone Linear Li-Ion Battery Charger with Thermal Regulation in DFN |
| 文件： | 总12页 (文件大小：182K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC4058-4.2/LTC4058X-4.2
Standalone Linear
Li-Ion Battery Charger with
Thermal Regulation in DFN
U
FEATURES
DESCRIPTIO
■
Programmable Charge Current Up to 950mA
The LTC®4058 is a complete constant-current/constant-
voltage linear charger for single cell lithium-ion batteries.
Its DFN package and low external component count make
the LTC4058 ideally suited for portable applications. Fur-
thermore, the LTC4058 is designed to work within USB
power specifications.
■
Complete Linear Charger in DFN Package
■
No MOSFET, Sense Resistor or Blocking Diode
Required
■
Thermal Regulation Maximizes Charge Rate
Without Risk of Overheating*
■
Battery Kelvin Sensing Improves Charging Accuracy
The LTC4058 can Kelvin sense the battery terminal for
more accurate float voltage charging. No external sense
resistor or external blocking diode are required due to the
internal MOSFET architecture. Thermal feedback regu-
latesthechargecurrenttolimitthedietemperatureduring
high power operation or high ambient temperature condi-
tions. The charge voltage is fixed at 4.2V and the charge
current is programmed with a resistor. The LTC4058
terminates the charge cycle when the charge current
drops to 10% of the programmed value after the final float
voltage is reached.
■
Charges Directly from a USB Port
C/10 Charge Termination
■
■
Preset 4.2V Charge Voltage with ±1% Accuracy
■
Charge Current Monitor Output for Gas Gauging*
■
Automatic Recharge
■
Charge Status Output
■
“AC Present” Output
■
2.9V Trickle Charge Threshold (LTC4058)
■
Available Without Trickle Charge (LTC4058X)
■
Soft-Start Limits Inrush Current
■
Low Profile (3mm × 3mm × 0.75mm) DFN Package
When the input supply (wall adapter or USB supply) is
removed,theLTC4058entersalowcurrentstatedropping
the battery drain current to less than 2µA. Other features
include charge current monitor, undervoltage lockout,
automatic recharge and status pins to indicate charge
termination and the presence of an input voltage.
U
APPLICATIO S
■
Cellular Telephones, PDAs, MP3 Players
Bluetooth Applications
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
*US Patent 6,522,118
U
TYPICAL APPLICATIO
Complete Charge Cycle (750mAh Battery)
700
600
500
400
300
200
100
0
4.75
4.50
4.25
4.00
3.75
3.50
3.25
3.00
CONSTANT
CURRENT
Single Cell Li-Ion Battery Charger with Kelvin Sense
CONSTANT
VOLTAGE
600mA
V
IN
V
CC
BAT
BSENSE
4.5V TO 6.5V
LTC4058-4.2
CHRG
ACPR
1-CELL
Li-Ion
BATTERY
+
EN
PROG
GND
V
= 5V
CC
JA
1.65k
1µF
θ
= 40°C/W
R
= 1.65k
PROG
405842 TA01
T
A
= 25°C
0.25 0.5 0.75 1.0 1.25
1.75 2.0 2.25
0
1.5
405842 TA02
TIME (HOURS)
sn405842 405842fs
1
LTC4058-4.2/LTC4058X-4.2
W W U W
ABSOLUTE AXI U RATI GS
(Note 1)
U W
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
Input Supply Voltage (VCC) ....................... –0.3V to 10V
PROG............................................. –0.3V to VCC + 0.3V
BAT, BSENSE.............................................. –0.3V to 7V
CHRG, ACPR, EN ...................................... –0.3V to 10V
BAT Short-Circuit Duration .......................... Continuous
BAT Pin Current ........................................................ 1A
PROG Pin Current................................................... 1mA
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
ORDER PART
NUMBER
BSENSE
BAT
1
2
3
4
8
7
6
5
EN
ACPR
LTC4058EDD-4.2
LTC4058XEDD-4.2
9
CHRG
GND
V
CC
PROG
DD PART MARKING
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
LAEV
LBDH
TJMAX = 125°C, θJA = 40°C/W (NOTE 3)
EXPOSED PAD IS GROUND (PIN 9)
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Supply Voltage
Input Supply Current
●
4.25
6.5
V
CC
I
Charge Mode (Note 4), R
Standby Mode (Charge Terminated)
Shutdown Mode (EN = 5V, V < V
= 10k
●
●
●
0.3
200
25
1
500
50
mA
µA
µA
CC
PROG
CC
BSENSE
or V < V
)
CC
UV
V
Regulated Output (Float) Voltage
BAT Pin Current
0°C ≤ T ≤ 85°C, 4.3V < V < 6.5V
4.158
4.2
4.242
V
FLOAT
A
CC
I
R
PROG
R
PROG
= 10k, Current Mode
= 2k, Current Mode
●
●
93
465
100
500
107
535
mA
mA
BAT
I
BSENSE Pin Current (Note 5)
Standby Mode, V
Shutdown Mode (EN = 5V, V < V
= 4.2V
●
–2.5
±1
–6
±2
µA
µA
BSENSE
BSENSE
or
BSENSE
CC
V
< V )
CC
UV
Sleep Mode, V = 0V
±1
45
±2
60
µA
mA
V
CC
I
Trickle Charge Current
V
< V
, R = 2k (Note 6)
TRIKL PROG
●
30
2.8
60
TRIKL
BSENSE
V
V
V
V
V
V
Trickle Charge Threshold Voltage
Trickle Charge Hysteresis Voltage
R
R
= 10k, V Rising (Note 6)
BSENSE
2.9
80
3
TRIKL
TRHYS
UV
PROG
PROG
= 10k (Note 6)
110
3.92
300
mV
V
V
V
Undervoltage Lockout Voltage
Undervoltage Lockout Hysteresis
From V Low to High
●
●
●
●
●
3.7
150
0.4
3.8
200
0.7
0.7
2
CC
CC
CC
mV
V
UVHYS
EN(IL)
EN(IH)
EN Pin Input Low Voltage
EN Pin Input High Voltage
EN Pin Pull-Down Resistor
1
5
V
R
1.2
MΩ
EN
V
V
– V
Lockout Threshold
V
V
from Low to High
from High to Low
70
5
100
30
140
50
mV
mV
ASD
CC
BSENSE
CC
CC
I
C/10 Termination Current Threshold
R
PROG
R
PROG
= 10k (I = 100mA) (Note 7)
CHG
●
●
0.085
0.085
0.10
0.10
0.115
0.115
mA/mA
mA/mA
TERM
= 2k (I
= 500mA)
CHG
V
V
V
PROG Pin Voltage
R
= 10k, Current Mode
= 5mA
0.93
1
1.07
0.6
V
V
PROG
CHRG
ACPR
PROG
CHRG
CHRG Pin Output Low Voltage
ACPR Pin Output Low Voltage
Recharge Battery Threshold Voltage
I
I
0.35
0.35
100
= 5mA
0.6
V
ACPR
∆V
V
– V
, 0°C ≤ T ≤ 85°C
60
140
mV
RECHRG
FLOAT
RECHRG
A
sn405842 405842fs
2
LTC4058-4.2/LTC4058X-4.2
ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
T
Junction Temperature in Constant
Temperature Mode
120
°C
LIM
R
ON
Power FET “ON” Resistance
600
mΩ
(Between V and BAT)
CC
t
t
t
Soft-Start Time
I
= 0 to I
=1000V/R
PROG
100
2
µs
ms
µs
SS
BAT
BAT
Recharge Comparator Filter Time
Termination Comparator Filter Time
V
High to Low
0.75
400
4.5
RECHARGE
TERM
BSENSE
I
Drops Below I /10
1000
2500
BAT
CHG
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LTC4058E-4.2/LTC4058XE-4.2 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 4: Supply current includes PROG pin current (approximately 100µA)
but does not include any current delivered to the battery through the BAT
pin (approximately 100mA).
Note 5: For all Li-Ion applications, the BSENSE pin must be electrically
connected to the BAT pin.
Note 6: This parameter is not applicable to the LTC4058X.
Note 3: Failure to solder the exposed backside of the package to the PC
board will result in a thermal resistance much higher than 40°C/W.
Note 7: I
with indicated PROG resistor.
is expressed as a fraction of measured full charge current
TERM
U W
TYPICAL PERFOR A CE CHARACTERISTICS
PROG Pin Voltage vs Supply
Voltage (Constant Current Mode)
PROG Pin Voltage
vs Temperature
Charge Current
vs PROG Pin Voltage
1.015
1.010
1.005
1.000
0.995
0.990
0.985
600
500
400
300
200
100
0
1.0100
1.0075
1.0050
1.0025
V
V
T
= 5V
V
V
= 5V
V
= 5V
CC
CC
CC
= V
= 4V
= V
= 4V
T = 25°C
A
BAT
BSENSE
BAT
PROG
BSENSE
= 10k
= 25°C
R
= 2k
PROG
R
A
R
= 10k
PROG
1.0000
0.9975
0.9950
0.9925
0.9900
4
5
5.5
(V)
6
6.5
7
–50
–25
0
50
75
100
0
0.4
0.6
(V)
PROG
0.8
1
1.2
4.5
25
0.2
V
V
TEMPERATURE (°C)
CC
405842 G01
405842 G02
405842 G03
sn405842 405842fs
3
LTC4058-4.2/LTC4058X-4.2
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Regulated Output (Float) Voltage
vs Charge Current
Regulated Output (Float) Voltage
vs Temperature
Regulated Output (Float) Voltage
vs Supply Voltage
4.26
4.215
4.210
4.205
4.200
4.195
4.190
4.185
4.215
4.210
4.205
4.200
4.195
4.190
4.185
V
A
R
= 5V
V
= 5V
PROG
T = 25°C
A
CC
CC
R
T
= 25°C
= 10k
R
= 10k
PROG
4.24
4.22
= 1.25k
PROG
4.20
4.18
4.16
4.14
4.12
4.10
100 200
400 500 600 700
(mA)
–50
0
25
50
75
100
4
5
5.5
(V)
6
6.5
7
0
300
–25
4.5
TEMPERATURE (°C)
V
I
CC
BAT
405842 G04
405842 G05
405842 G06
CHRG Pin I-V Curve
(Pull-Down State)
ACPR Pin I-V Curve
(Pull-Down State)
Trickle Charge Current
vs Temperature
30
25
20
15
30
25
20
15
60
50
40
30
20
10
0
V
V
= 5V
CC
T
= –40°C
T
A
= –40°C
A
= V
= 2.5V
BAT
BSENSE
T
T
= 25°C
= 90°C
T
T
= 25°C
= 90°C
A
A
A
A
R
= 2k
PROG
10
5
10
5
R
= 10k
50
PROG
25
V
V
= 5V
V
V
= 5V
CC
CC
= V
BSENSE
= 4V
= V
BSENSE
= 4V
BAT
BAT
0
0
4
6
7
4
6
7
–50
0
75
100
0
1
2
3
5
0
1
2
3
5
–25
TEMPERATURE (°C)
V
CHRG
(V)
V
ACPR
(V)
405842 G07
405842 G08
405842 G09
Trickle Charge Current
vs Supply Voltage
Trickle Charge Threshold Voltage
vs Temperature
Charge Current vs Battery Voltage
60
50
40
30
20
10
0
600
500
400
300
3.000
2.975
2.950
2.925
V
T
= V
= 2.5V
BSENSE
V
= 5V
PROG
BAT
A
CC
= 25°C
R
= 10k
R
= 2k
PROG
2.900
2.875
200
100
0
2.850
2.825
2.800
R
= 10k
6
PROG
V
= 5V
CC
JA
θ
= 40°C/W
R
= 2k
PROG
4
5
5.5
(V)
6.5
7
–50
–25
0
50
75
100
2.4 2.7
3
3.3 3.6 3.9
(V)
4.2
4.5
4.5
25
V
TEMPERATURE (°C)
V
BAT
CC
405842 G10
405842 G11
405842 G08
sn405842 405842fs
4
LTC4058-4.2/LTC4058X-4.2
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Charge Current
vs Ambient Temperature
Recharge Threshold Voltage
vs Temperature
Charge Current vs Supply Voltage
600
500
400
300
200
100
0
600
500
400
300
4.16
V
= 5V
CC
ONSET OF THERMAL REGULATION
R
= 2k
R
= 10k
PROG
PROG
4.14
4.12
4.10
4.08
4.06
4.04
R
PROG
= 2k
V
T
JA
= V
= 4V
V
V
θ
= 5V
= V
BAT
A
BSENSE
CC
= 25°C
= 4V
BAT
BSENSE
θ
= 40°C/W
= 40°C/W
JA
200
100
0
R
= 10k
50
R
PROG
= 10k
PROG
25
4
5
5.5
6
6.5
7
–50 –25
0
75
100 125
–50
0
25
50
75
100
4.5
–25
V
CC
(V)
TEMPERATURE (°C)
TEMPERATURE (°C)
405842 G13
405842 G14
405842 G15
Power FET “ON” Resistance
vs Temperature
Power FET Transistor Curve
800
800
700
600
500
V
V
V
= 5V
BAT
BSENSE
V
V
T
= 5V
CC
CC
BSENSE
= 4.8V
= 3.5V
= 25°C
= 4V
A
700
600
500
R
= 2k
R
PROG
= 2k
PROG
400
300
200
100
0
400
300
–50
0
25
50
75
100
–25
4.1
4.4
V
5
3.8
5.3
4.7
(V)
TEMPERATURE (°C)
BAT
405842 G17
405842 G16
U
U
U
PI FU CTIO S
BSENSE (Pin 1): Battery Sense. This pin is used to Kelvin
sense the positive battery terminal and regulate the final
float voltage to 4.2V. An internal precision resistor divider
sets this float voltage and is disconnected in shutdown
mode. For Li-Ion applications, this pin must be electri-
cally connected to BAT.
internal N-channel MOSFET. When the charge cycle is
completed, CHRG becomes high impedance.
GND (Pins 4, 9): Ground/Exposed Pad. The exposed
backside of the package (Pin 9) is also ground and must
be soldered to the PC board for maximum heat transfer.
PROG (Pin 5): Charge Current Program and Charge Cur-
rent Monitor. Charge current is programmed by connect-
ing a 1% resistor, RPROG, to ground. When charging in
constant-currentmode,thispinservosto1V.Inallmodes,
BAT (Pin 2): Charge Current Output. Provides charge
currenttothebatteryfromtheinternalP-channelMOSFET.
CHRG (Pin 3): Charge Status Open-Drain Output. When
the battery is charging, the CHRG pin is pulled low by an
sn405842 405842fs
5
LTC4058-4.2/LTC4058X-4.2
U
U
U
PI FU CTIO S
the voltage on this pin can be used to measure the charge
ACPR (Pin 7): Power Supply Status Open-Drain Output.
WhenVCC isgreaterthantheundervoltagelockoutthresh-
old and at least 100mV above VBSENSE, the ACPR pin is
pulled to ground; otherwise, the pin is high impedance.
current using the following formula:
IBAT = (VPROG/RPROG) • 1000
Thispinisclampedtoapproximately2.4V. Drivingthispin
tovoltagesbeyondtheclampvoltagecandrawcurrentsas
high as 1.5mA.
EN(Pin8):EnableInput. AlogichighontheENpinwillput
the LTC4058 into shutdown mode where the battery drain
current is reduced to less than 2µA and the supply current
is reduced to less than 50µA. A logic low or floating the EN
pin (allowing an internal 2MΩ pull-down resistor to pull
this pin low) enables charging.
VCC (Pin 6): Positive Input Supply Voltage. Provides
power to the charger. VCC can range from 4.25V to 6.5V.
This pin should be bypassed with at least a 1µF capacitor.
When VCC is within 100mV of the BSENSE pin voltage, the
LTC4058 enters shutdown mode dropping the battery
drain current to less than 2µA.
W
BLOCK DIAGRA
6
V
CC
120°C
T
A
T
DIE
1×
1000×
BAT
–
+
2
1
5µA
BSENSE
MA
R1
ACPR
CHRG
+
7
3
VA
R2
–
CA
+
REF
1.21V
–
R3
1V
CHARGE ACPR
LOGIC
R4
0.1V
R5
+
–
TERM
C1
EN
SHDN
EN
TRICKLE CHARGE
DISABLED ON THE
LTC4058X
8
R
C2
EN
+
–
2.9V
TO BAT
PROG
GND
4, 9
5
R
PROG
405842 BD
sn405842 405842fs
6
LTC4058-4.2/LTC4058X-4.2
U
OPERATIO
The LTC4058 is a single cell lithium-ion battery charger
using a constant-current/constant-voltage algorithm. It
can deliver up to 950mA of charge current (using a good
thermal PCB layout) with a final float voltage accuracy of
±1%. The LTC4058 includes an internal P-channel power
MOSFET and thermal regulation circuitry. No blocking
diode or external current sense resistor is required; thus,
the basic charger circuit requires only two external com-
ponents. Furthermore, the LTC4058 is capable of operat-
ing from a USB power source.
Charge Termination
The charge cycle terminates when the charge current falls
to 10% the programmed value after the final float voltage
is reached. This condition is detected by using an internal,
filtered comparator to monitor the PROG pin. When the
PROG pin voltage falls below 100mV1 for longer than
tTERM (typically 1ms), charging is terminated. The charge
current is latched off and the LTC4058 enters standby
mode where the input supply current drops to 200µA.
(Note: C/10 termination is disabled in trickle charging and
thermal limiting modes.)
Normal Charge Cycle
When charging, transient loads on the BAT pin can cause
thePROGpintofallbelow100mVforshortperiodsoftime
before the DC charge current has dropped to 10% of the
programmed value. The 1ms filter time (tTERM) on the
termination comparator ensures that transient loads of
this nature do not result in premature charge cycle termi-
nation. Once the averagecharge current drops below 10%
of the programmed value, the LTC4058 terminates the
charge cycle and ceases to provide any current through
the BAT pin. In this state, all loads on the BAT pin must be
supplied by the battery.
AchargecyclebeginswhenthevoltageattheVCC pinrises
abovetheUVLOthresholdlevelanda1%programresistor
is connected from the PROG pin to ground. If the BSENSE
pinislessthan2.9V,thechargerenterstricklechargemode.
In this mode, the LTC4058 supplies approximately 1/10th
the programmed charge current to bring the battery volt-
age up to a safe level for full current charging. (Note: The
LTC4058X does not include this trickle charge feature.)
WhentheBSENSEpinvoltagerisesabove2.9V,thecharger
enters constant-current mode where the programmed
chargecurrentissuppliedtothebattery.WhentheBSENSE
pin approaches the final float voltage (4.2V), the LTC4058
enters constant-voltage mode and the charge current be-
ginstodecrease. Whenthechargecurrentdropsto1/10th
of the programmed value, the charge cycle ends.
The LTC4058 constantly monitors the BAT pin voltage in
standbymode.Ifthisvoltagedropsbelowthe4.1Vrecharge
threshold (VRECHRG), another charge cycle begins and
charge current is once again supplied to the battery. To
manuallyrestartachargecyclewheninstandbymode, the
inputvoltagemustberemovedandreappliedorthecharger
mustbeshutdownandrestartedusingtheENpin.Figure 1
shows the state diagram of a typical charge cycle.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. The charge current out of
the BAT pin is 1000 times the current out of the PROG pin.
The program resistor and the charge current are calcu-
lated using the following equations:
Charge Status Indicator (CHRG)
The charge status output has two states: pull-down and
high impedance. The pull-down state indicates that the
LTC4058 is in a charge cycle. Once the charge cycle has
terminated or the LTC4058 is disabled, the pin state
becomes high impedance.
1000V
ICHG
1000V
RPROG
RPROG
=
, ICHG =
ChargecurrentoutoftheBATpincanbedeterminedatany
time by monitoring the PROG pin voltage and using the
following equation:
1Any external sources that hold the PROG pin above 100mV will prevent the LTC4058 from
terminating a charge cycle.
VPROG
RPROG
IBAT
=
•1000
sn405842 405842fs
7
LTC4058-4.2/LTC4058X-4.2
U
OPERATIO
POWER ON
chargerwillautomaticallyreducethecurrentinworst-case
conditions. DFN power considerations are discussed fur-
ther in the Applications Information section.
BSENSE < 2.9V
TRICKLE CHARGE
MODE
EN DRIVEN LOW
OR
UVLO CONDITION
STOPS
1/10TH FULL CURRENT
Undervoltage Lockout (UVLO)
CHRG: STRONG
PULL-DOWN
Aninternalundervoltagelockoutcircuitmonitorstheinput
voltageandkeepsthechargerinshutdownmodeuntilVCC
risesabovetheundervoltagelockoutthreshold. TheUVLO
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 VCC
falls to within 30mV of the BSENSE voltage. If the UVLO
comparator is tripped, the charger will not come out of
shutdown mode until VCC rises 100mV above the BSENSE
voltage.
BSENSE > 2.9V
BSENSE > 2.9V
SHUTDOWN MODE
CHARGE MODE
FULL CURRENT
CHRG: STRONG
I
DROPS TO <25µA
CC
CHRG: Hi-Z
PULL-DOWN
PROG < 100mV
STANDBY MODE
NO CHARGE CURRENT
CHRG: Hi-Z
EN DRIVEN HIGH
OR
UVLO CONDITION
2.9V < BSENSE < 4.1V
405842 F01
Manual Shutdown
Figure 1. State Diagram of a Typical Charge Cycle
At any point in the charge cycle, the LTC4058 can be put
into shutdown mode by driving the EN pin high. This
reduces the battery drain current to less than 2µA and the
supply current to less than 50µA. When in shutdown
mode, the CHRG pin is in the high impedance state. A new
charge cycle can be initiated by driving the EN pin low. A
resistor pull-down on this pin forces the LTC4058 to be
enabled if the pin is allowed to float.
Power Supply Status Indicator (ACPR)
The power supply status output has two states: pull-down
and high impedance. The pull-down state indicates that
VCC isabovetheUVLOthreshold(3.8V)andisalso100mV
above the battery voltage. When these conditions are not
met, the ACPR pin is high impedance indicating that the
LTC4058 is unable to charge the battery.
Thermal Limiting
Automatic Recharge
Aninternalthermalfeedbackloopreducestheprogrammed
chargecurrentifthedietemperatureattemptstoriseabove
apresetvalueofapproximately120°C.Thisfeatureprotects
the LTC4058 from excessive temperature and allows the
user to push the limits of the power handling capability of
agivencircuitboardwithoutriskofdamagingtheLTC4058.
Thechargecurrentcanbesetaccordingtotypical(notworst
case) ambient temperature with the assurance that the
Oncethechargecycleisterminated,theLTC4058continu-
ously monitors the voltage on the BSENSE pin using a
comparator with a 2ms filter time (tRECHARGE). A charge
cycle restarts when the battery voltage falls below 4.10V
(whichcorrespondstoapproximately80%to90%battery
capacity). 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 enters
a pull-down state during recharge cycles.
sn405842 405842fs
8
LTC4058-4.2/LTC4058X-4.2
U
W U U
APPLICATIO S I FOR ATIO
Kelvin Sensing the Battery (BSENSE Pin)
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 2. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
The internal P-channel MOSFET drain is connected to the
BAT pin, while the BSENSE pin connects through an inter-
nal precision resistor divider to the input of the constant-
voltageamplifier. ThisarchitectureallowstheBSENSEpin
to Kelvin sense the positive battery terminal. This is espe-
cially useful when the copper trace from the BAT pin to the
Li-Ion battery is long and has a high resistance. High
charge currents can cause a significant voltage drop be-
tween the positive battery terminal and the BAT pin. In this
situation, a separate trace from the BSENSE pin to the
battery terminals will eliminate this voltage error and re-
sultinmoreaccuratebatteryvoltagesensing.TheBSENSE
pin MUST be electrically connected to the BAT pin.
LTC4058-4.2
CHARGE
10k
CURRENT
PROG
MONITOR
CIRCUITRY
R
PROG
C
FILTER
GND
405842 F02
Figure 2. Isolating Capacitive Load on PROG Pin and Filtering
Stability Considerations
Power Dissipation
The constant-voltage mode feedback loop is stable with-
out an output capacitor, provided a battery is connected to
the charger output. With no battery present, an output
capacitor on the BAT pin is recommended to reduce ripple
voltage. When using high value, low ESR ceramic capaci-
tors, it is recommended to add a 1Ω resistor in series with
the capacitor. No series resistor is needed if tantalum
capacitors are used.
It is not necessary to design for worst-case power dissi-
pation scenarios because the LTC4058 automatically re-
duces the charge current during high power conditions.
The conditions that cause the LTC4058 to reduce charge
currentthroughthermalfeedbackcanbeapproximatedby
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:
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. The pole frequency
at the PROG pin should be kept above 100kHz. Therefore,
if the PROG pin is loaded with a capacitance, CPROG, the
following equation can be used to calculate the maximum
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. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
TA = 120°C – PDθJA
TA = 120°C – (VCC – VBAT) • IBAT • θJA
Example: An LTC4058 operating from a 5V supply is
programmed to supply 800mA full-scale current to a
dischargedLi-Ionbatterywithavoltageof3.3V.Assuming
θJA is 50°C/W (see Thermal Considerations), the ambient
temperatureatwhichtheLTC4058willbegintoreducethe
charge current is approximately:
resistance value for RPROG
:
1
RPROG
≤
2π •105 •CPROG
Average, ratherthaninstantaneouschargecurrentmaybe
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
TA = 120°C – (5V – 3.3V) • (800mA) • 50°C/W
TA = 120°C – 1.36W • 50°C/W = 120°C – 68°C
TA = 52°C
sn405842 405842fs
9
LTC4058-4.2/LTC4058X-4.2
W U U
U
APPLICATIO S I FOR ATIO
The LTC4058 can be used above 52°C ambient but the
ceramiccapacitors.Becauseoftheself-resonantandhigh
chargecurrentwillbereducedfrom800mA.Theapproxi- Q characteristics of some types of ceramic capacitors,
mate current at a given ambient temperature can be high voltage transients can be generated under some
approximated by:
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, see Application
Note 88.
120°C – TA
V – V • θ
CC JA
IBAT
=
(
)
BAT
Using the previous example with an ambient temperature
of 60°C, the charge current will be reduced to
approximately:
Charge Current Soft-Start
The LTC4058 includes a soft-start circuit to minimize the
inrushcurrentatthestartofachargecycle.Whenacharge
cycle is initiated, the charge current ramps from zero to
thefull-scalecurrentoveraperiodofapproximately100µs.
Thishastheeffectofminimizingthetransientcurrentload
on the power supply during start-up.
120°C – 60°C
5V – 3.3V • 50°C/W 85°C/A
60°C
IBAT
=
=
(
)
IBAT = 706mA
Moreover,whenthermalfeedbackreducesthechargecur-
rentthevoltageatthePROGpinisalsoreducedproportion-
ally as discussed in the Operation section. It is important
to remember that LTC4058 applications do not need to be
designedforworst-casethermalconditionssincetheICwill
automatically reduce power dissipation when the junction
temperature reaches approximately 120°C.
USB and Wall Adapter Power
The LTC4058 allows charging from both a wall adapter
and a USB port. Figure 3 shows an example of how to
combinewall adapterand USB powerinputs. AP-channel
MOSFET, MP1, is used to prevent back conducting into
the USB port when a wall adapter is present and a
Schottky diode, D1, is used to prevent USB power loss
through the 1k pull-down resistor.
Thermal Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on the
backside of the LTC4058 package is soldered to the PC
board ground. Correctly soldered to a 2500mm2 double-
sided 1oz copper board, the LTC4058 has a thermal
resistance of approximately 40°C/W. Failure to make
thermal contact between the exposed pad on the back-
side of the package and the copper board will result in
thermal resistances far greater than 40°C/W. As an
example, a correctly soldered LTC4058 can deliver over
800mA to a battery from a 5V supply at room tempera-
ture. Without a backside thermal connection, this num-
ber will drop considerably.
Typically a wall adapter can supply more current than the
500mA-limited USB port. Therefore, an N-channel
MOSFET, MN1, and an extra 3.3k program resistor are
used to increase the charge current to 800mA when the
wall adapter is present.
5V WALL
ADAPTER
I
CHG
800mA I
LTC4058-4.2
BAT
CHG
2
1
5
SYSTEM
LOAD
D1
6
USB POWER
500mA I
V
CC
BSENSE
CHG
4, 9
MP1
GND PROG
+
Li-Ion
BATTERY
3.3k
1k
2k
MN1
VCC Bypass Capacitor
405842 F03
Many types of capacitors can be used for input bypassing,
however,cautionmustbeexercisedwhenusingmultilayer
Figure 3. Combining Wall Adapter and USB Power
sn405842 405842fs
10
LTC4058-4.2/LTC4058X-4.2
U
W U U
APPLICATIO S I FOR ATIO
DRAIN-BULK
DIODE OF FET
Reverse Polarity Input Voltage Protection
LTC4058
CC
In some applications, protection from reverse polarity
voltage on VCC is desired. If the supply voltage is high
enough, a series blocking diode can be used. In other
cases,wherethevoltagedropmustbekeptlow,aP-channel
MOSFET can be used (as shown in Figure 4).
V
V
IN
405842 F04
Figure 4. Low Loss Input Reverse Polarity Protection
U
PACKAGE DESCRIPTIO
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 ±0.05
3.5 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
PACKAGE
OUTLINE
0.28 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
0.38 ± 0.10
TYP
5
8
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(DD8) DFN 0203
4
1
0.28 ± 0.05
0.75 ±0.05
0.200 REF
0.50 BSC
2.38 ±0.10
(2 SIDES)
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. ALL DIMENSIONS ARE IN MILLIMETERS
3. 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
4. EXPOSED PAD SHALL BE SOLDER PLATED
sn405842 405842fs
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.
11
LTC4058-4.2/LTC4058X-4.2
U
TYPICAL APPLICATIO S
Full Featured Single Cell Li-Ion Charger
Li-Ion Battery Charger with Reverse Polarity Input Protection
V
IN
5V
5V
WALL
1k
1k
6
ADAPTER
6
500mA
V
500mA
CC
V
2
BAT
CC
BAT
BSENSE
2
1
7
3
ACPR
CHRG
1
BSENSE
4.7µF
LTC4058-4.2
1-CELL
Li-Ion
BATTERY
LTC4058-4.2
+
1-CELL
Li-Ion
BATTERY
+
8
5
4.7µF
8
5
EN PROG
EN PROG
GND
4, 9
2k
GND
4, 9
1µF
2k
405842 TA04
405842 TA03
USB/Wall Adapter Power Li-Ion Charger
I
BAT
2
1
BAT
BSENSE
5V WALL
ADAPTER
+
LTC4058-4.2
Li-Ion
CELL
6
USB
POWER
V
CC
2.5k
5
1µF
PROG
GND
100mA/
500mA
1k
4, 9 10k
µC
405842 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1732
Lithium-Ion Linear Battery Charger Controller
Simple Charger uses External FET, Features Preset Voltages, C/10
Charger Detection and Programmable Timer, Input Power Good Indication
Standalone Charger with Programmable Timer, Up to 1.5A Charge Current
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
LTC1733
LTC1734
LTC1734L
LTC1998
LTC4007
Monolithic Lithium-Ion Linear Battery Charger
Lithium-Ion Linear Battery Charger in ThinSOTTM
Lithium-Ion Linear Battery Charger in ThinSOT
Lithium-Ion Low Battery Detector
Low Current Version of LTC1734; 50mA ≤ I
≤ 180mA
CHRG
1% Accurate 2.5µA Quiescent Current, SOT-23
4A Multicell Li-Ion Battery Charger
Standalone Charger, 6V ≤ V ≤ 28V, Up to 96% Efficiency,
IN
±0.8% Charging Voltage Accuracy
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
LTC4054
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
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
LTC4410
Li-Ion Linear Battery Charger
USB Power Manager
Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package
For Simultaneous Operation of USB Peripheral and Battery Charging from USB
Port, Keeps Current Drawn from USB Port Constant, Keeps Battery Fresh, Use
with the LTC4053, LTC1733, or LTC4054
LTC4412
Low Loss PowerPathTM Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
sn405842 405842fs
LT/TP 1103 1K • PRINTED IN USA
12 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
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