LINER LTC4062 Standalone linear li-ion battery charger with micropower comparator Datasheet

LTC4062
Standalone Linear Li-Ion
Battery Charger with
Micropower Comparator
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FEATURES
DESCRIPTIO
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The LTC®4062 is a full-featured, flexible, standalone linear
charger for single-cell Lithium-Ion batteries. It is capable
of operating within USB power specifications.
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Charge Current Programmable Up to 1A
Charges Single-Cell Li-Ion Batteries Directly from
USB Port
Preset Float Voltage with ±0.35% Accuracy
Micropower Comparator for Battery Monitoring
Thermal Regulation Maximizes Charge Rate
Without Risk of Overheating
Programmable Charge Current Detection/
Termination
Programmable Charge Termination Timer
Smart Pulsing Error Feature
SmartStartTM Prolongs Battery Life
20µA Charger Quiescent Current in Shutdown
Available in a Low Profile (0.75mm) 10-Lead
(3mm × 3mm) DFN Package
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APPLICATIO S
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Handheld Computers
Portable MP3 Players
Digital Cameras
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
SmartStart is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6522118.
Both programmable time and programmable current based
termination schemes are available. Furthermore, the CHRG
open-drain status pin can be programmed to indicate the
battery charge state according to the needs of the application. A precise low power comparator is available even
with no power applied as long as battery voltage is higher
than 2.5V. Additional safety features designed to maximize battery lifetime and reliability include the SmartStart
charging algorithm.
No external sense resistor or external blocking diode is
required for charging due to the internal MOSFET architecture. Internal thermal feedback regulates the charge current to maintain a constant die temperature during high
power operation or high ambient temperature conditions.
The charge current is programmed with an external resistor. With power applied, the LTC4062 can be put into
shutdown mode to reduce the supply current to 20µA and
the battery drain current to less than 5µA. Without power
applied, the internal low power comparator can work
sinking only 10µA from the battery.
Other features include smart recharge, USB C/5 current
programming input and undervoltage lockout.
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TYPICAL APPLICATIO
Complete Charge Cycle (1100mAh Battery)
VCC
1µF
619Ω
OUT
LTC4062
EN
C/5
BAT
TIMER
PROG
IDET
IN+
GND
BAT > 3V BAT < 3V
100k
800mA
715k
+
347k
SINGLE-CELL
Li-Ion BATTERY
900
4.3
800
4.2
700
4.1
600
4.0
3.9
500
BATTERY
VOLTAGE
400
3.8
3.7
300
3.6
200
VCC = 5V
TA = 25°C
100
4062 TA01
BATTERY
CURRENT
BATTERY VOLTAGE (V)
VIN
4.3V TO 8V
CHARGE CURRENT (mA)
800mA Single-Cell Li-Ion Battery Charger
(C/10 Termination)
3.5
0
0
0.5
1.5
1.0
2.0
TIME (HOURS)
2.5
3.4
3.0
4062 TA01b
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LTC4062
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ABSOLUTE
AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
Input Supply Voltage (VCC) ........................ –0.3V to 10V
EN, OUT, CHRG, IN+, PROG, C/5, BAT ....... –0.3V to 10V
TIMER, IDET ..................................... –0.3V to VCC +0.3V
BAT Short-Circuit Duration ...........................Continuous
VCC Pin Current ......................................................... 1A
BAT Pin Current ......................................................... 1A
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Temperature Range .................. –65°C to 125°C
10 VCC
BAT
IN+
1
TIMER
3
OUT
4
8 IDET
7 EN
CHRG
5
6 C/5
9 PROG
2
11
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 40°C/W (NOTE 3)
EXPOSED PAD IS GROUND (PIN 11)
MUST BE SOLDERED TO PCB
ORDER PART NUMBER
DD PART MARKING
LTC4062EDD
LBJT
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 ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, unless otherwise noted.
SYMBOL
PARAMETER
VCC
Input Supply Voltage
ICC
Input Supply Current
VFLOAT
VBAT Regulated Output Voltage
CONDITIONS
MIN
●
Charge Mode (Note 4), RPROG = 10k
Standby Mode, Charge Terminated
Shutdown (EN = 5V, VCC < VBAT or VCC < VUV)
4.3
●
●
●
●
MAX
UNITS
8
V
240
130
20
500
300
50
µA
µA
µA
4.185
4.175
4.2
4.2
4.215
4.225
V
V
93
760
100
800
–3.5
±1
107
840
–7
±5
mA
mA
µA
µA
0.97
0.97
1
1
1.03
1.03
V
V
●
●
●
0 < TA < 85°C
TYP
IBAT
BAT Pin Current
RPROG = 10k, Constant Current Mode
RPROG = 1.25k, Constant Current Mode
Standby Mode, Charge Terminated, VBAT = 4.2V
Shutdown Mode, VBAT = 4.2V
VPROG
PROG Pin Voltage
RPROG = 10k, Constant Current Mode
RPROG = 1.25k, Constant Current Mode
VOUT
OUT Output Low Voltage
IOUT = 5mA
IOUT = 5mA, VCC = 0V, VBAT = 2.55V
0.10
0.16
0.25
0.26
V
V
VCHRG
CHRG Output Low Voltage
ICHRG = 5mA
0.1
0.25
V
ITRIKL
Trickle Charge Current
VBAT < VTRIKL, RPROG = 10k
VBAT < VTRIKL, RPROG = 1.25k
6
60
10
80
14
100
mA
mA
VTRIKL
Trickle Charge Threshold Voltage
VBAT Rising
Hysteresis
2.8
2.9
100
3
V
mV
VUV
VCC Undervoltage Lockout
Voltage
From Low to High
Hysteresis
3.7
3.8
200
3.9
V
V
VASD
VCC – VBAT Lockout Threshold
Voltage
VCC from Low to High, VBAT = 4.3V
VCC from High to Low, VBAT = 4.3V
145
10
190
45
230
75
mV
mV
REN
EN Pin Pull-Down Resistor
2
3.4
5
MΩ
●
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LTC4062
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
VEN
EN Input Threshold Voltage
EN Rising, 4.3V < VCC < 8V
Hysteresis
0.4
0.7
70
1
V
mV
VCT
Charge Termination Mode Threshold
Voltage
VTIMER from High to Low
Hysteresis
0.4
0.7
50
1
V
mV
VUT
User Termination Mode Threshold
Voltage
VTIMER from Low to High
Hysteresis
3.9
4.2
50
IDETECT
Charge Current Detection Threshold
RDET = 1k, 0 ≤ TA ≤ 85°C
RDET = 2k, 0 ≤ TA ≤ 85°C
RDET = 10k, 0 ≤ TA ≤ 85°C
RDET = 20k, 0 ≤ TA ≤ 85°C
90
45
8
3.8
100
50
10
5
110
55
12
6.2
mA
mA
mA
mA
∆VRECHRG
Recharge Threshold Voltage
VFLOAT – VRECHRG, 0 ≤ TA ≤ 85°C
65
100
135
mV
tSS
Soft-Start Time
IBAT from 0 to ICHG
tTERM
Termination Comparator Filter Time
Current Termination Mode
tRECHRG
Recharge Comparator Filter Time
tTIMER
Charge Cycle Time
RC/5
C/5 Pin Pull-Down Resistor
VC/5
C/5 Input Threshold Voltage
TLIM
Junction Temperature in Constant
Temperature Mode
RON
Power FET “ON” Resistance
(Between VCC and BAT)
VBAT = 3.85V, ICC = 175mA, RPROG = 2k
VIN+
IN+ Pin Threshold Voltage
VIN+ Falling
Hysteresis
VBAT-MIN
Minimum VBAT Supply Voltage for the
Low Power Comparator
IBAT
Supply Current for the Low Power
Comparator
V
mV
µs
100
CTIMER = 0.1µF
●
C/5 Rising, 4.3V < VCC < 8V
Hysteresis
UNITS
0.8
1.5
2.5
ms
3
7
14
ms
2.55
3
3.45
2
3.4
5
MΩ
0.4
0.7
70
1
V
mV
hr
105
°C
375
mΩ
Comparator
●
0.988
1
50
1.012
V
mV
VCC = 0V, VBAT Falling
Hysteresis
2.4
2.5
100
2.6
V
mV
VCC = 0V, VBAT = 2.5V
7
9
13
µA
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 LTC4062 is 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 correctly solder the exposed pad of the package to the
PC board will result in a thermal resistance much higher than 40°C/W.
Note 4: Supply current includes PROG pin current and IDET pin current
(approximately 100µA each) but does not include any current delivered to
the battery through the BAT pin (approximately 100mA).
Note 5: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions.
Overtemperature protection will become active at a junction temperature
greater than the maximum operating temperature. Continuous operation
above the specified maximum operating junction temperature may impair
device reliability.
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LTC4062
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TYPICAL PERFOR A CE CHARACTERISTICS
Battery Regulated Output (Float)
Voltage vs Charge Current
4.26
Battery Regulated Output (Float)
Voltage vs Temperature
4.215
VCC = 5V
RPROG = 1k
4.24
TA = 25°C unless otherwise noted.
Battery Regulated Output (Float)
Voltage vs Supply Voltage
4.26
VCC = 5V
RPROG = 10k
4.210
4.22
4.22
VFLOAT (V)
VFLOAT (V)
4.18
4.16
VFLOAT (V)
4.205
4.20
4.200
4.18
4.16
4.14
4.190
4.12
4.10
200
800
600
CHARGE CURRENT (mA)
0
400
4.12
4.185
–50
1000
–25
0
25
50
TEMPERATURE (°C)
75
1.006
800
1.006
RPROG = 10k
C/5 = VCC
1.002
VPROG (V)
VPROG (V)
VCC = 8V
1.000
VCC = 4.3V
1.000
400
0.998
0.998
200
0.996
0.996
0.2
0.4
0.6
0.8
1.0
1.2
0.994
–50
–25
VPROG (V)
0
25
50
TEMPERATURE (°C)
75
84
2.96
VCC = 5V
VBAT = 2.5V
RPROG = 1.25k
100
0.994
4.0
4.5 5.0
5.5
6.0
6.5
7.0
7.5
8.0
VCC (V)
4062 G04
Trickle Charge Current vs
Temperature
8.0
VCC = 5V
VBAT = 4V
RPROG = 10k
C/5 = 5V
1.004
1.002
0
7.0 7.5
PROG Pin Voltage vs VCC
(Constant-Current Mode)
1.004
600
6.0 6.5
4062 G03
PROG Pin Voltage vs Temperature
(Constant-Current Mode)
VCC = 5V
RPROG = 1k
C/5 = 5V
VTIMER = 5V
1000
5.0 5.5
4062 G02
Charge Current vs PROG
Pin Voltage
1200
4.10
4.0 4.5
100
VCC (V)
4062 G01
IBAT (mA)
4.20
4.195
4.14
0
RPROG = 1k
TA = 25°C
IBAT = 10mA
4.24
4062 G05
4062 G06
Trickle Charge Threshold Voltage
vs Temperature
Charge Current vs Battery Voltage
550
VCC = 5V
RPROG = 1.25k
C/5 = 5V
2.94
450
80
IBAT (mA)
2.92
VTRICKLE (V)
ITRICKLE (mA)
82
2.90
350
250
2.88
78
76
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4062 G07
2.84
–50
VCC = 5V
RPROG = 2k
150
2.86
–25
0
25
50
TEMPERATURE (°C)
75
100
4062 G08
C/5 = 0V
50
3.2
3.0
3.6
3.4
VBAT (V)
3.8
4.0
4062 G09
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TYPICAL PERFOR A CE CHARACTERISTICS
Charge Current vs Ambient
Temperature with Thermal
Regulation
Internal Charge Timer vs
Temperature
195
Charge Current vs Supply Voltage
1000
104
VCC = 5V
VBAT = 4V
C/5 = 5V
RPROG = 10k
ONSET OF THERMAL
REGULATION
190
tTIMER (MINUTES)
TA = 25°C unless otherwise noted.
VCC = 4.3V
800
VCC = 8V
600
RPROG = 1.25k
102
180
IBAT (mA)
IBAT (mA)
185
RPROG = 2k
400
100
175
200
170
165
–50
CTIMER = 0.1µF
–25
0
25
50
TEMPERATURE (°C)
75
98
VCC = 5V
VBAT = 4V
θJA = 40°C/W
0
–50
100
50
25
0
75
TEMPERATURE (°C)
–25
100
96
125
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
4062 G10
4062 G13
Recharge Threshold Voltage vs
Temperature
4062 G14
Power FET “ON” Resistance vs
Temperature
4.16
500
4.14
450
8.0
VCC (V)
Undervoltage Lockout Voltage vs
Temperature
3.900
VCC = 4V
IBAT = 200mA
3.875
3.850
VCC = 8V
4.10
VCC = 4.3V
3.825
400
VUV (V)
RDS(ON) (mΩ)
VRECHARGE (V)
4.12
350
3.775
4.08
3.750
300
4.06
3.725
4.04
–50
–25
0
25
50
TEMPERATURE (°C)
75
250
–50
100
–25
0
25
50
TEMPERATURE (°C)
75
700
REN (MΩ)
600
500
400
300
–25
50
25
0
TEMPERATURE (°C)
100
75
4062 G17
C/5 Pin Pulldown Resistance vs
Temperature
5.0
5.0
4.5
4.5
4.0
4.0
RC/5 (MΩ)
VCC = 5V
C/5 = 5V
RPROG = 1.25k
θJA = 40°C/W
800
3.700
– 50
EN Pin Pulldown Resistance vs
Temperature
Charge Current vs Battery Voltage
900
100
4062 G16
4062 G15
IBAT (mA)
3.800
3.5
3.5
3.0
3.0
2.5
2.5
200
100
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
VBAT (V)
4062 G18
2.0
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
4062 G19
2.0
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
4062 G20
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TYPICAL PERFOR A CE CHARACTERISTICS
EN Pin Threshold Voltage
(On-to-Off) vs Temperature
Shutdown Supply Current vs
Temperature and VCC
C/5 Pin Threshold Voltage
(High-to-Low) vs Temperature
900
900
VCC = 5V
70
VCC = 5V
EN = VCC
850
60
800
800
50
750
ICC (µA)
850
VC/5 (mV)
VEN (mV)
TA = 25°C unless otherwise noted.
750
40
700
700
30
650
650
20
600
–50
600
–50
10
–50
VCC = 8V
VCC = 5V
VCC = 4.3V
–25
75
0
25
50
TEMPERATURE (°C)
100
–25
50
25
0
TEMPERATURE (°C)
100
4062 G23
0.6
VCC = 5V
VBAT = 4V
TA = – 40°C
120
VCC = 5V
ICHRG = 5mA
0.5
TA = 25°C
0.4
TA = 90°C
100
VCHRG (V)
IOUT (mA)
75
CHRG Pin Output Low Voltage vs
Temperature
OUT Pin I-V Curve
140
0
25
50
TEMPERATURE (°C)
–25
4062 G22
4062 G21
160
100
75
80
60
0.3
0.2
40
0.1
20
0
0
2
1
3
0
–50
4
50
25
0
TEMPERATURE (°C)
–25
VOUT (V)
4062 G25
4062 G24
OUT Pin Output Low Voltage vs
Temperature
0.6
0.5
CHRG Pin I-V Curve
160
VCC = 5V
IOUT = 5mA
IN+ ≥ 1.05V
VCC = 5V
VBAT = 4V
140
TA = –40°C
120
ICHRG (mA)
0.4
VOUT (V)
100
75
0.3
0.2
TA = 25°C
TA = 90°C
100
80
60
40
0.1
0
–50
20
–25
50
25
0
TEMPERATURE (°C)
75
100
4062 G26
0
0
1
2
VCHRG (V)
3
4
4062 G27
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PI FU CTIO S
BAT (Pin 1): Charge Current Output. This pin provides
charge current to the battery and regulates the final float
voltage to 4.2V.
IN+ (Pin 2): Positive Input of the Micropower Comparator.
The negative input is tied internally to a precise bandgap
voltage reference of 1V. There is approximately 50mV of
hysteresis associated with the input comparator threshold
(rising edge).
TIMER (Pin 3): Timer Program and Termination Select
Pin. This pin selects which method is used to terminate the
charge cycle. Connecting a capacitor, CTIMER, to ground
selects charge time termination. The charge time is set by
the following formula:
CTIMER
or
0.1µF
TIME (HOURS)
CTIMER = 0.1µF •
3 (HOURS)
TIME (HOURS) = 3 (HOURS) •
Connecting the TIMER pin to ground selects charge current termination, while connecting the pin to VCC selects
user termination. See Applications Information for more
information on current and user termination.
OUT (Pin 4): Low Power Comparator Open-Drain Output.
This comparator output pin has two states; pull-down and
high impedance. This output can be used as a logic
interface or as an LED driver. In the pull-down state, an
NMOS transistor capable of sinking 10mA pulls down on
the OUT pin. The state of this pin is dependent on the value
of IN+. When IN+ is greater than 1V the output pin is in pulldown state, if IN+ is less than 1V the output pin is in high
impedance state. See Applications Information.
CHRG (Pin 5): Open-Drain Charge Status Output. The
charge status indicator pin has three states: pull-down,
pulse at 6Hz and high impedance. This output can be used
as a logic interface or as a LED driver. In the pull-down
state, an NMOS transistor capable of sinking 10mA pulls
down on the CHRG pin. The state of this pin depends on the
value of IDETECT as well as the termination method being
used. See Applications Information.
C/5 (Pin 6): C/5 Enable Input. Used to control the amount
of current drawn by the charger when powered from a USB
port. A logic high on the C/5 pin sets the current limit to
100% of the current programmed by the PROG pin. A logic
low on the C/5 pin sets the current limit to 20% of the current
programmed by the PROG pin. An internal 3MΩ pull-down
resistor defaults the C/5 pin to its low current state.
EN (Pin 7): Charger Enable Input. A logic high on the EN
pin places the charger into shutdown mode, where the
input quiescent current is less than 50µA. A logic low on
this pin enables charging. An internal 3MΩ pull-down
resistor to ground defaults the charger to its enabled state.
IDET (Pin 8): Current Detection Threshold Program Pin.
The current detection threshold, IDETECT, is set by connecting a resistor, RDETECT, to ground. IDETECT is set by the
following formula:
RPROG
100V
• ICHG =
or
10RDET
RDET
100V
IDETECT =
RDET =
IDETECT
The CHRG pin becomes high impedance when the charge
current drops below IDETECT. IDETECT can be set to 1/10th
the programmed charge current by connecting IDET directly to PROG. If the IDET pin is not connected, the CHRG
output remains in its pull-down state until the charge time
elapses and terminates the charge cycle. See Applications
Information.
This pin is clamped to approximately 2.4V. Driving this pin
to voltages beyond the clamp voltage should be avoided.
PROG (Pin 9): Charge Current Program and Charge Current Monitor. The charge current is set by connecting a
resistor, RPROG, to ground. When charging in constant
current mode, this pin servos to 1V. The voltage on this pin
can be used to measure the charge current using the
following formula:
IBAT =
VPROG
• 1000
RPROG
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VCC (Pin 10): Positive Input Supply Voltage. Provides
power to the battery charger. This pin should be bypassed
with a 1µF capacitor.
GND (Exposed Pad) (Pin 11): Ground. This pin is the back
of the exposed metal pad package and must be soldered
to the PCB copper for minimal thermal resistance.
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BLOCK DIAGRA
10
VCC
+
4.1V
–
TO BAT
2
C1
1×
1×
IN+
1000×
–
BAT
+
1
MA
OUT
+
4
C4
CA
–
5
1V
–
VA
+
+
–
CHRG
1V
1.2V
STOP
0.2V
RECHRG
6
0.1V
C/5
C/5
LOGIC
3M
LOGIC
7
EN
TERM
EN
C/5
3M
SEL
C2
+
C3
+
–
TO BAT
2.9V
–
COUNTER
0.1V
OSCILLATOR
+
TDIE
–
105°C
TA
SHDN
IDET
TIMER
3
8
PROG
9
GND
11
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CTIMER
RDET
RPROG
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LTC4062
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OPERATIO
The LTC4062 is designed to charge single-cell lithium-ion
batteries. Using the constant current/constant voltage
algorithm, the charger can deliver up to 1A of charge
current with a final float voltage accuracy of ±0.35%. The
LTC4062 includes an internal P-channel power MOSFET
and thermal regulation circuitry. No blocking diode or
external sense resistor is required; thus, the basic charger
circuit requires only two external components.
Normal Operation
The charge cycle begins when the voltage at the VCC pin
rises above the UVLO level and a discharged battery is
connected to BAT. If the BAT pin voltage is below 2.9V, the
charger enters trickle charge mode. In this mode, the
LTC4062 supplies 1/10th of the programmed charge
current in order to bring the battery voltage up to a safe
level for full current charging.
Once 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 LTC4062
enters constant voltage mode and the charge current
decreases as the battery becomes fully charged.
The LTC4062 offers several methods with which to terminate a charge cycle. Connecting an external capacitor to
the TIMER pin activates an internal timer that stops the
charge cycle after the programmed time period has elapsed.
Grounding the TIMER pin and connecting a resistor to the
IDET pin causes the charge cycle to terminate once the
charge current falls below a set threshold when the charger
is in constant voltage mode. Connecting the TIMER pin to
VCC disables internal termination, allowing external charge
user termination through the EN input. See Applications
Information for more information on charge termination
methods.
Programming Charge Current
The charge current is programmed using a single resistor
from the PROG pin to ground. When the charger is in the
constant current mode, the voltage on the PROG pin is 1V.
The battery charge current is 1000 times the current out of
the PROG pin. The program resistor and the charge
current are calculated by the following equations:
RPROG =
1000 V
1000 V
, ICHG =
ICHG
RPROG
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage and
applying the following equation:
IBAT =
VPROG
• 1000
RPROG
SmartStart
When the LTC4062 is initially powered on or brought out
of shutdown mode, the charger checks the battery voltage.
If the BAT pin is below the recharge threshold of 4.1V
(which corresponds to approximately 80-90% battery
capacity), the LTC4062 enters charge mode and begins a
full charge cycle. If the BAT pin is above 4.1V, the LTC4062
enters standby mode and does not begin charging. This
feature reduces the number of unnecessary charge cycles,
prolonging battery life.
Automatic Recharge
When the charger is in standby mode, the LTC4062
continuously monitors the voltage on the BAT pin. When
the BAT pin voltage drops below 4.1V, the charge cycle is
automatically restarted and the internal timer is reset to
50% of the programmed charge time (if time termination
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LTC4062
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OPERATIO
is being used). This feature eliminates the need for periodic charge cycle initiations and ensures that the battery
is always fully charged. Automatic recharge is disabled in
user termination mode.
Thermal Regulation
An internal thermal feedback loop reduces the programmed
charge current if the die temperature attempts to rise
above a preset value of approximately 105°C. This feature
protects the LTC4062 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 LTC4062. The charge current can be set according to
typical (not worst-case) ambient temperatures with the
assurance that the charger will automatically reduce the
current in worst-case conditions.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input
voltage and keeps the charger in shutdown mode until VCC
rises above the undervoltage lockout threshold (3.8V).
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 VCC falls to less than 45mV above the
battery voltage. Hysteresis of 145mV prevents the charger
from cycling in and out of shutdown.
Manual Shutdown
At any point in the charge cycle, the charger can be put into
shutdown mode by pulling the EN pin high. This reduces
the supply current to less than 50µA and the battery drain
current of the charger to less than 2µA. A new charge cycle
can be initiated by floating the EN pin or pulling it low.
If shutdown is not required, leaving the pin disconnected
continuously enables the circuit.
Trickle-Charge and Defective Battery Detection
When the BAT pin voltage is below the 2.9V trickle charge
threshold (VTRIKL), the charger reduces the charge current
to 10% of the programmed value. If the battery remains in
trickle charge for more than 25% of the total programmed
charge time, the charger stops charging and enters a
FAULT state, indicating that the battery is defective1. The
LTC4062 indicates the FAULT state by driving the CHRG
open-drain output with a square wave. The duty cycle of
this oscillation is 50% and the frequency is set by CTIMER:
fCHRG =
0.1µF
• 6Hz
CTIMER
A LED driven by the CHRG output exhibits a pulsing
pattern, indicating to the user that the battery needs
replacing. To exit the FAULT state, the charger must be
restarted either by toggling the EN input or removing and
reapplying power to VCC.
Charge Status Output (CHRG)
The charge status indicator pin has three states: pulldown, pulse at 6Hz and high impedance. In the pull-down
state, an NMOS transistor pulls down on the CHRG pin
capable of sinking up to 10mA. A pull-down state indicates
that the LTC4062 is charging a battery and the charge
current is greater than IDETECT (which is set by the external
component RDET). A high impedance state indicates that
the charge current has dropped below IDETECT. In the case
where the IDET pin is left unconnected (RDET = ∞, IDETECT
= 0), a high impedance state on CHRG indicates that the
LTC4062 is not charging.
1The Defective Battery Detection Feature is only available when time termination is being used.
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Smart Pulsing Error Feature
LTC4062 has a pulsing state at the CHRG pull-down pin of
6Hz (50% duty cycle) due to defective battery detection
(see Trickle-Charge and Defective Battery Detection section).
Low Power Comparator (IN+; OUT)
The low power, low offset comparator is designed with an
internal 1V reference connected to the negative input. This
reference is generated by a precise bandgap circuit. The
comparator output drives a pull down NMOS transistor
able to sink up to 10mA. Voltages lower than 1V at the IN+
pin set the OUT pin to a high impedance state.
Voltages higher than 1V plus a built-in 50mV hysteresis at
the IN+ pin set the OUT pin to a low impedance state. The
comparator is operational even when VCC is not applied
provided the BAT pin voltage is greater than 2.5V. When
the voltage at the BAT pin drops below 2.5V, the comparator shuts down and the current at the BAT pin is reduced
to <1µA.
4
2
OUT
IN+
+
1V
–
LTC4062
4062 F01
Figure 1. Low Power Comparator Circuit
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Programming Charge Termination
The LTC4062 can terminate a charge cycle using one of
several methods, allowing the designer considerable flexibility in choosing an ideal charge termination algorithm.
Table 1 shows a brief description of the different termination methods and their behaviors.
Charge Time Termination
Connecting a capacitor (CTIMER) to the TIMER pin enables
the timer and selects charge time termination. The total
charge time is set by:
TIME (HOURS) =
CTIMER
• 3 HOURS
0.1µF
When the programmed time has elapsed, the charge cycle
terminates and the charger enters standby mode. Subsequent recharge cycles terminate when 50% of the programmed time has elapsed. The IDET pin determines the
behavior of the CHRG output. Connecting a resistor (RDET)
from the IDET pin to ground sets the charge current
detection threshold, IDETECT:
RPROG
100V
• ICHG =
or
10RDET
RDET
100V
IDETECT =
RDET =
IDETECT
When the charge current (I BAT ) is greater than
IDETECT, the CHRG output is in its pull-down state. When
the charger enters constant voltage mode operation and
the charge current falls below IDETECT, the CHRG output
becomes high impedance, indicating that the battery is
almost fully charged. The CHRG output will also become
high impedance once the charge time elapses. If the IDET
pin is not connected, the CHRG output remains in its pulldown state until the charge time elapses and terminates
the charge cycle.
Figure 2 shows a charger circuit using charge time termination that is programmed to charge at 500mA. Once the
charge current drops below 100mA in constant voltage
mode (as set by RDET), the CHRG output turns off the LED.
This indicates to the user that the battery is almost fully
charged and ready to use. The LTC4062 continues to
Table 1
METHOD
Charge
Time
Termination
Mode
Charge
Current
Termination
User
Selectable
Charge
Termination
TIMER
0.1µF to
GND
IDET
RDET to
GND
CHARGER DESCRIPTION
Charges for 3 Hours. After 3 Hours, the Charger
Stops Charging and Enters Standby Mode.
Recharge Cycles Last for 1.5 Hours.
CHRG OUTPUT DESCRIPTION
Pull-Down State While IBAT > IDET. High Impedance
State While IBAT < IDETECT or When Charging Is Stopped.
Pulsing State Available When NTC Is Used and
Is Still Charging.
0.1µF to
GND
NC
Charges for 3 Hours. After 3 Hours, the Charger
Stops Charging and Enters Standby Mode.
Recharge Cycles Last for 1.5 Hours.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
GND
RDET to
GND
Charges Until Charge Current Drops Below
IDET, Then Enters Standby Mode.
GND
NC
VCC
RDET to
GND
Charges Indefinitely.
SmartStart Is Disabled.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
Pull-Down State While IBAT > IDETECT. High Impedance
State While IBAT < IDETECT or When Charging Is Stopped.
Pulsing State Available When NTC Is Used and
Is Still Charging.
VCC
NC
Charges Indefinitely.
SmartStart Is Disabled.
Charges Indefinitely.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
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12
LTC4062
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charge the battery until the internal timer reaches 3 hours
(as set by CTIMER). During recharge cycles, the LTC4062
charges the battery until the internal timer reaches
1.5 hours. Figure 3 describes the operation of the LTC4062
charger when charge time termination is used.
Charge Current Termination
Connecting the TIMER pin to ground selects charge current termination. With this method, the timer is disabled
and a resistor (RDET) must be connected from the IDET pin
to ground. IDETECT is programmed using the same equation stated in the previous section. The charge cycle
terminates when the charge current falls below IDETECT.
This condition is detected using an internal filtered comparator to monitor the IDET pin. When the IDET pin falls
below 100mV for longer than tTERM (typically 1.5ms),
charging is terminated.
500mA
VIN
VCC
BAT
C/5 LTC4062
CHRG
PROG
RPROG
2k
IDET
RDET
1k
+
TIMER
GND
CTIMER
0.1µF
4062 F02
When charging, transient loads on the BAT pin can cause
the IDET pin to fall below 100mV for short periods of time
before the DC current has dropped below the IDETECT
Figure 2. Time Termination Mode.
The Charge Cycle Ends After 3 Hours
POWER ON
DEFECTIVE BATTERY
FAULT MODE
NO CHARGE CURRENT
CHRG STATE: PULSING
1/4 CHARGE TIME
ELAPSES
EN = 0V
OR UVLO
CONDITION
STOPS
TRICKLE CHARGE MODE
1/10TH FULL CURRENT
CHRG STATE: PULL-DOWN
BAT < 2.9V
BAT > 2.9V
CHARGE MODE
SHUTDOWN MODE
FULL CURRENT
ICC DROPS TO 20µA
CHRG STATE:
2.9V < BAT < 4.1V PULL-DOWN IF IBAT > IDETECT
Hi-Z IF IBAT < IDETECT
CHRG STATE: Hi-Z
CHARGE TIME
ELAPSES
STANDBY MODE
BAT > 4.1V
NO CHARGE CURRENT
EN = 5V
OR
UVLO CONDITION
CHRG STATE: Hi-Z
BAT < 4.1V
RECHARGE MODE
FULL CURRENT
1/2 CHARGE
TIME ELAPSES
CHRG STATE:
PULL-DOWN IF IBAT > IDETECT
Hi-Z IF IBAT < IDETECT
4062 F03
Figure 3. State Diagram of a Charge Cycle
Using Charge Time Termination
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threshold. The 1.5ms filter time (tTERM) on the internal
comparator ensures that transient loads of this nature do
not result in premature charge cycle termination. Once the
average charge current drops below IDETECT, the charger
terminates the charge cycle.
When the charger is set for charge current termination and
the battery is removed from the charger, a sawtooth
waveform of several hundred mV will appear at the charger
output. This is caused by the repeated cycling between
termination and recharge events. This cycling results in
pulsing at the CHRG output. If an LED is connected to this
pin, it will exhibit a pulsing pattern, indicating to the user
that a battery is not present. The frequency of the sawtooth
is dependent on the amount of output capacitance.
The CHRG output is in a pull-down state while charging
and in a high impedance state once charging has stopped.
Figure 4 describes the operation of the LTC4062 charger
when charge current termination is used.
POWER ON
TRICKLE CHARGE MODE
1/10TH FULL CURRENT
EN = 0V
OR UVLO
CONDITION
STOPS
CHRG STATE: PULL-DOWN
BAT < 2.9V
BAT > 2.9V
2.9V < BAT < 4.1V
CHARGE MODE
SHUTDOWN MODE
FULL CURRENT
ICC DROPS TO 20µA
CHRG STATE: Hi-Z
CHRG STATE: PULL-DOWN
IBAT < IDETECT
IN VOLTAGE MODE
BAT < 4.1V
STANDBY MODE
NO CHARGE CURRENT
EN = 5V
OR
UVLO CONDITION
CHRG STATE: Hi-Z
BAT > 4.1V
4062 F04
Figure 4. State Diagram of a Charge Cycle Using Charge Current Termination
POWER ON
EN = 0V
OR UVLO
CONDITION
STOPS
TRICKLE CHARGE MODE
1/10TH FULL CURRENT
SHUTDOWN MODE
CHRG STATE: PULL-DOWN
ICC DROPS TO 20µA
BAT < 2.9V
BAT > 2.9V
CHRG STATE: Hi-Z
CHARGE MODE
FULL CURRENT
CHRG STATE:
2.9V < BAT PULL-DOWN IF IBAT > IDETECT
Hi-Z IF IBAT < IDETECT
4062 F05
EN = 5V
OR
UVLO CONDITION
Figure 5. State Diagram of a Charge Cycle Using User-Selectable Termination
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User-Selectable Charge Termination
Connecting the TIMER pin to VCC selects user-selectable
charge termination, in which all of the internal termination
features are disabled. The charge cycle continues indefinitely until the charger is shut down through the EN pin.
The IDET pin programs the behavior of the CHRG output in
the same manner as when using charge time termination.
If the IDET pin is not connected, the CHRG output remains
in its pull-down state until the charger is shut down.
With user-selectable charge termination, the SmartStart
feature is disabled; when the charger is powered on or
enabled, the LTC4062 automatically begins charging, regardless of the battery voltage. Figure 5 describes charger
operation when user-selectable charge termination is used.
Programming C/10 Current Detection/Termination
In most cases, an external resistor, RDET, is needed to set
the charge current detection threshold, IDETECT. However,
when setting IDETECT to be 1/10th of ICHG, the IDET pin can
be connected directly to the PROG pin. This reduces the
component count, as shown in Figure 6.
500mA
VIN
VCC
BAT
C/5 LTC4062
PROG
RPROG
2k
IDET
TIMER
GND
VCC
BAT
RDET
2k
+
500mA
VIN
C/5 LTC4062
PROG
RPROG
1k
IDET
+
TIMER
GND
When PROG and IDET are connected in this way, the fullscale charge current, ICHG, is programmed with a different
equation:
RPROG =
500V
500V
, ICHG =
ICHG
RPROG
Stability Considerations
The battery charger constant voltage mode feedback loop
is stable without any compensation provided a battery is
connected. However, a 1µF capacitor with a 1Ω series
resistor to GND is recommended at the BAT pin to reduce
noise when no battery is present.
When the charger is in constant current mode, the PROG
pin is in the feedback loop, not the battery. The constant
current 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
10kΩ; however, additional capacitance on this node reduces the maximum allowed program resistor value.
Power Dissipation
When designing the battery charger circuit, it is not
necessary to design for worst-case power dissipation
scenarios because the LTC4062 automatically reduces
the charge current during high power conditions. The
conditions that cause the LTC4062 to reduce charge
current through thermal feedback can be approximated
by considering the power dissipated in the IC. Most of the
power dissipation is generated from the internal charger
MOSFET. Thus, the power dissipation is calculated to be
approximately:
PD = (VCC – VBAT) • IBAT
4062 F06
Figure 6. Two Circuits That Charge at 500mA
Full-Scale Current and Terminate at 50mA
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 = 105°C – PD • θJA
TA = 105°C – (VCC – VBAT) • IBAT • θJA
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Example: An LTC4062 operating from a 5V wall adapter is
programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.3V. Assuming
θJA is 40°C/W (see Thermal Considerations), the ambient
temperature at which the LTC4062 will begin to reduce the
charge current is approximately:
TA = 105°C – (5V – 3.3V) • (800mA) • 40°C/W
TA = 105°C – 1.36W • 40°C/W = 105°C – 54.4°C
TA = 50.6°C
The LTC4062 can be used above 50.6°C ambient, but the
charge current will be reduced from 800mA. The approximate current at a given ambient temperature can be
approximated by:
IBAT =
105°C – TA
(VCC – VBAT )• θ JA
Using the previous example with an ambient temperature
of 60°C, the charge current will be reduced to
approximately:
105°C – 60°C
45°C
=
(5V – 3.3V)• 40°C /W 68°C /A
= 662mA
IBAT =
IBAT
It is important to remember that LTC4062 applications do
not need to be designed for worst-case thermal conditions, since the IC will automatically reduce power dissipation if the junction temperature reaches approximately
105°C.
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 LTC4062 package is properly soldered to
the PC board ground. Correctly soldered to a 2500mm2
double sided 1oz copper board, the LTC4062 has a thermal resistance of approximately 40°C/W. Failure to make
thermal contact between the exposed pad on the backside
of the package and the copper board will result in thermal
resistances far greater than 40°C/W. As an example, a
correctly soldered LTC4062 can deliver over 800mA to a
battery from a 5V supply at room temperature. Without a
good backside thermal connection, this number could
drop to less than 500mA.
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multilayer ceramic capacitors. Because of the self-resonant and
high Q characteristics of some types of ceramic capacitors, 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, see Application
Note 88.
Charge Current Soft-Start and Soft-Stop
The LTC4062 includes a soft-start circuit to minimize the
inrush current at the start of a charge cycle. When a charge
cycle is initiated, the charge current ramps from zero to the
full-scale current over a period of approximately 100µs.
Likewise, internal circuitry slowly ramps the charge current from full-scale to zero when the charger is shut off or
self terminates. This has the effect of minimizing the
transient current load on the power supply during start-up
and charge termination.
Reverse Polarity Input Voltage Protection
In some applications, protection from reverse polarity on
VCC is desired. If the supply voltage is high enough, a
series blocking diode can be used. In other cases, where
the diode voltage drop must be kept low, a P-channel
MOSFET can be used (as shown in Figure 7).
DRAIN-BULK
DIODE OF FET
LTC4062
VIN
VCC
4062 F07
Figure 7. Low Loss Input Reverse Polarity Protection
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USB and Wall Adapter Power
Typically a wall adapter can supply more current than
the 500mA limited USB port. Therefore, an N-channel
MOSFET, MN1, and an extra 3.3kΩ program resistor are
used to increase the charge current to 800mA when the
wall adapter is present.
The LTC4062 allows charging from both a wall adapter
and a USB port. Figure 8 shows an example of how to
combine wall adapter and USB power inputs. A P-channel
MOSFET, MP1, is used to prevent back conducting into the
USB port when a wall adapter is present and a Schottky
diode, D1, is used to prevent USB power loss through the
1kΩ pull-down resistor.
5V WALL
ADAPTER
ICHG = 800mA
USB POWER
ICHG = 500mA
D1
VCC
MP1
SYSTEM
LOAD
BAT
LTC4062
IDET
C/5
+
PROG
Li-Ion
BATTERY
3.3k
1k
MN1
2k
1.24k
4062 F08
Figure 8. Combining Wall Adapter and USB Power
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TYPICAL APPLICATIO S
Full-Featured Li-Ion Charger with Low-Battery Comparator (Using Time Termination)
VIN
4.3V TO 8V
VCC
OUT
BAT > 3V BAT < 3V
LTC4062
1µF
1.24k
0.1µF
619Ω
EN
C/5
BAT
TIMER
PROG
IDET
IN+
GND
100k
800mA
715k
+
347k
SINGLE-CELL
Li-Ion BATTERY
4062 TA03
USB/Wall Adapter Power Li-Ion Charger
(Using Charge Current Termination)
5V
WALL ADAPTER
400mA
USB
POWER
BAT
VCC
+
LTC4062
1µF
C/5
Li-Ion
CELL
PROG
IDET
TIMER
GND
2k
2.5k
4062 TA04
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18
LTC4062
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PACKAGE DESCRIPTIO
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1669)
0.675 0.05
3.50 0.05
1.65 0.05
2.15 0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 0.05
0.50
BSC
2.38 0.05
(2 SIDES)
R = 0.115
TYP
6
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
3.00 0.10
(4 SIDES)
0.38 0.10
10
1.65 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
(DD10) DFN 1103
5
0.200 REF
1
0.25 0.05
0.50 BSC
0.75 0.05
0.00 – 0.05
2.38 0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
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
4062fb
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTC4062
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1734
Lithium-Ion Linear Battery Charger in ThinSOTTM
Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed
LTC1734L
Lithium-Ion Linear Battery Charger in ThinSOT
Low Current Version of LTC1734, 50mA ≤ ICHRG ≤ 180mA
LTC4002
Switch Mode Lithium-Ion Battery Charger
Standalone, 4.7V ≤ VIN ≤ 24V, 500kHz Frequency, 3 Hour Charge Termination
LTC4050
Lithium-Ion Linear Battery Charger Controller
Features Preset Voltages, C/10Charger Detection and Programmable Timer,
Input Power Good Indication, Thermistor Interface
LTC4052
Monolithic Lithium-Ion Battery Pulse Charger
No Blocking Diode or External Power FET Required, ≤1.5A Charge Current
LTC4053
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
Lithium-Ion Linear Battery Charger
Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package
LTC4058
Standalone 950mA Lithium-Ion Charger in DFN
C/10 Charge Termination, Battery Kelvin Sensing, ±7% Charge Accuracy
LTC4059
900mA Linear Lithium-Ion Battery Charger
2mm × 2mm DFN Package, Thermal Regulation, Charge Current Monitor
Output
LTC4061/
LTC4061-4.4
Standalone Li-Ion Chargers with Thermistor
4.2V/4.4V, ±0.35%/±0.4% Float Voltage, Up to 1A Charge Current,
Thermistor Input, 3mm × 3mm DFN Package
LTC4063
Li-Ion Charger with Linear Regulator
Up to 1A Charge Current, 100mA, 125mV LDO, 3mm × 3mm DFN
Battery Chargers
LTC4411/LTC4412
TM
Low Loss PowerPath Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
LTC3405/LTC3405A
300mA (IOUT), 1.5MHz, Synchronous Step-Down
DC/DC Converter
95% Efficiency, VIN: 2.7V to 6V, VOUT = 0.8V, IQ = 20µA, ISD < 1µA,
ThinSOT Package
LTC3406/LTC3406A
600mA (IOUT), 1.5MHz, Synchronous Step-Down
DC/DC Converter
95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.6V, IQ = 20µA, ISD < 1µA,
ThinSOT Package
LTC3411
1.25A (IOUT), 4MHz, Synchronous Step-Down
DC/DC Converter
95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.8V, IQ = 60µA, ISD < 1µA,
MS Package
LTC3440
600mA (IOUT), 2MHz, Synchronous Buck-Boost
DC/DC Converter
95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 2.5V, IQ = 25µA, ISD < 1µA,
MS Package
LTC4413
Dual Ideal Diode in DFN
2-Channel Ideal Diode ORing, Low Forward On-Resistance, Low Regulated
Forward Voltage, 2.5V ≤ VIN ≤ 5.5V
Power Management
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
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Linear Technology Corporation
LT/LWI 0906 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
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www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005