LINER LTC4061EDD Standalone linear li-lon battery charger with thermistor input Datasheet

LTC4061
Standalone Linear Li-Ion Battery
Charger with Thermistor Input
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FEATURES
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DESCRIPTIO
Charge Current Programmable up to 1A
Charges Single Cell Li-Ion Batteries Directly from
USB Port
Preset Charge Voltage with ±0.35% Accuracy
Thermistor Input for Temperature Qualified
Charging
Input Supply Present Logic Output
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
The LTC®4061 is a full-featured, flexible, standalone linear
charger for single-cell Lithium-Ion batteries. It is capable
of operating within USB power specifications.
Both programmable time and programmable current
based termination schemes are available. Furthermore,
the ⎯C⎯H⎯R⎯G open-drain status pin can be programmed to
indicate the battery charge state according to the needs
of the application. Additional safety features designed to
maximize battery lifetime and reliability include NTC battery temperature sensing and the SmartStartTM 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 LTC4061 can be put into
shutdown mode to reduce the supply current to 20µA and
the battery drain current to less than 2µA.
Other features include smart recharge, USB ⎯C⎯/⎯5 current programming input, undervoltage lockout and AC
Present logic.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
SmartStart is a trademark of Linear Technology Corporation.
*Protected by U.S. Patents including 6522118.
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Complete Charge Cycle (1100mAh Battery)
TYPICAL APPLICATIO
VCC
1µF
BAT
EN LTC4061
CHRG
C/5
TIMER
PROG
IDET
619Ω
ACPR
+
NTC
GND
4.2V
SINGLE CELL
Li-Ion BATTERY
900
4.3
800
4.2
700
4.1
600
4.0
3.9
500
BATTERY
VOLTAGE
400
BATTERY
CURRENT
3.8
3.7
300
3.6
200
VCC = 5V
TA = 25°C
100
3.5
0
4061 TA01a
BATTERY VOLTAGE (V)
800mA
VIN
4.3V TO 8V
CHARGE CURRENT (mA)
800mA Single Cell Li-Ion Battery Charger
(C/10 Termination)
0
0.5
1.5
1.0
2.0
TIME (HOURS)
2.5
3.4
3.0
4061 TA01b
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LTC4061
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ABSOLUTE
AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
Input Supply Voltage (VCC) ........................ –0.3V to 10V
⎯E⎯N, ⎯A⎯C⎯P⎯R, ⎯C⎯H⎯R⎯G, NTC, 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 (Note 5) ............ 125°C
Operating Temperature Range (Note 2) ...–40°C to 85°C
Storage Temperature Range...................–65°C to 125°C
ORDER PART
NUMBER
TOP VIEW
10 VCC
9 PROG
BAT
1
NTC
2
TIMER
3
ACPR
4
7 EN
CHRG
5
6 C/5
11
LTC4061EDD
8 IDET
DD PART
MARKING
TJMAX = 125°C, θJA = 40°C/W (NOTE 3)
EXPOSED PAD IS GROUND (PIN 11)
MUST BE SOLDERED TO PCB
LBJS
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the 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
VCC
Input Supply Voltage
●
ICC
Input Supply Current
Charge Mode (Note 4), RPROG = 10k
●
Standby Mode, Charge Terminated
●
Shutdown (⎯E⎯N = 5V, VCC < VBAT or VCC < VUV) ●
VFLOAT
VBAT Regulated Output Voltage
0 ≤ TA ≤ 85°C
●
●
●
●
TYP
MAX
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
±1
±1
107
840
±2
±2
mA
mA
µA
µA
0.97
0.97
1
1
1.03
1.03
V
V
0.1
0.25
V
4.3
UNITS
IBAT
BAT Pin Current
RPROG = 10k, Constant Current Mode
RPROG = 1.25k, Constant Current Mode
Standby Mode, Charge Terminated
Shutdown Mode
VPROG
PROG Pin Voltage
RPROG = 10k, Constant Current Mode
RPROG = 1.25k, Constant Current Mode
V⎯A⎯C⎯P⎯R
⎯A⎯C⎯P⎯R Output Low Voltage
I⎯A⎯C⎯P⎯R = 5mA
V⎯C⎯H⎯R⎯G
⎯C⎯H⎯R⎯G Output Low Voltage
I⎯C⎯H⎯R⎯G = 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
mV
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
R⎯E⎯N
⎯E⎯N Pin Pull-Down Resistor
2
3.4
5
MΩ
V⎯E⎯N
⎯E⎯N Input Threshold Voltage
E⎯ ⎯N 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
●
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LTC4061
ELECTRICAL CHARACTERISTICS
The ● denotes the 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
VUT
User Termination Mode Threshold
Voltage
VTIMER from Low to High
Hysteresis
3.9
4.2
50
IDETECT
Charge Current Detection Threshold
ΔVRECHRG
tSS
tTERM
tRECHRG
tTIMER
R⎯C⎯/⎯5
V⎯C⎯/⎯5
Recharge Threshold Voltage
Soft-Start Time
Termination Comparator Filter Time
Recharge Comparator Filter Time
Charge Cycle Time
⎯C⎯/5 Pin Pull-Down Resistor
⎯ /⎯ 5 Input Threshold Voltage
C
RDET = 1k, 0 ≤ TA ≤ 85°C
RDET = 2k, 0 ≤ TA ≤ 85°C
RDET = 10k, 0 ≤ TA ≤ 85°C
RDET = 20k, 0 ≤ TA ≤ 85°C
VFLOAT – VRECHRG, 0 ≤ TA ≤ 85°C
IBAT from 0 to ICHRG
Current Termination Mode
90
45
8
3.8
65
100
50
10
5
100
100
1.5
7
3
3.4
VNTC-HOT
NTC Pin Hot Threshold Voltage
VNTC Falling
VNTC Rising
VNTC-COLD
NTC Pin Cold Threshold Voltage
VNTC Rising
VNTC Falling
VNTC-DIS
NTC Pin Disable Threshold Voltage
VNTC Falling
Hysteresis
f⎯C⎯H⎯R⎯G
NTC Fault Pulsing Frequency
Current/User Termination Mode
Time Termination Mode CTIMER = 0.1µF
TLIM
Junction Temperature in Constant
Temperature Mode
RON
Power FET “ON” Resistance
(Between VCC and BAT)
CTIMER = 0.1µF
●
⎯C⎯/⎯5 Rising, 4.3V < VCC < 8V
Hysteresis
0.4
70
VBAT = 3.85V, ICC = 175mA, RPROG = 2k
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LTC4061 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.
0.8
3
2.55
2
1
0.7
70
0.35 • VCC
0.36 • VCC
0.76 • VCC
0.75 • VCC
85
50
1.5
1.5
105
375
MAX
UNITS
V
mV
110
55
12
6.2
135
2.5
14
3.45
5
1
100
2
mA
mA
mA
mA
mV
µs
ms
ms
hr
MΩ
V
mV
V
V
V
V
mV
mV
Hz
Hz
°C
mΩ
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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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
Battery Regulated Output (Float)
Voltage vs Supply Voltage
4.26
VCC = 5V
RPROG = 10k
4.22
4.20
4.18
4.16
VFLOAT (V)
4.205
VFLOAT (V)
VBAT (V)
4.22
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
100
0.994
4.0
4.5
5.0
5.5
6.0
6.5
7.0
Trickle Charge Threshold Voltage
vs Temperature
VCC = 5V
VBAT = 2.5V
RPROG = 1.25k
8.0
4061 G06
4061 G05
2.96
7.5
VCC (V)
4061 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
4061 G03
PROG Pin Voltage vs Temperature
(Constant-Current Mode)
VCC = 5V
RPROG = 1k
C/5 = 5V
VTIMER = 5V
1000
5.0 5.5
4061 G02
Charge Current vs PROG Pin
Voltage
1200
4.10
4.0 4.5
100
VCC (V)
4061 G01
IBAT (mA)
4.20
4.195
4.14
0
RPROG = 1k
TA = 25°C
IBAT = 10mA
4.24
4.210
Charge Current vs Battery Voltage
550
VCC = 5V
RPROG = 1.25k
C/5 = 5V
2.94
450
80
2.92
IBAT (mA)
VTRICKLE (V)
ITRICKLE (mA)
82
2.90
350
250
2.88
78
76
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4061 G07
2.84
–50
VCC = 5V
RPROG = 2k
150
2.86
–25
0
25
50
TEMPERATURE (°C)
75
100
4061 G08
C/5 = 0V
50
3.2
3.0
3.6
3.4
VBAT (V)
3.8
4.0
4061 G09
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TYPICAL PERFOR A CE CHARACTERISTICS
NTC Fault Pulsing Frequency
vs VCC
Internal Charge Timer vs
Temperature
195
NTC Fault Pulsing Frequency
vs Temperature
1.7
1.60
CTIMER = 0.1µF
CTIMER = 0.1µF
1.55
VCC = 4.3V
185
1.6
180
1.45
175
1.40
170
1.35
165
–50
fCHRG (Hz)
1.50
VCC = 8V
fCHRG (Hz)
tTIMER (MINUTES)
190
0
25
50
TEMPERATURE (°C)
75
1.30
4.0
100
4.5
5.5
5.0
6.0
6.5
7.0
1.2
–50
8.0
7.5
–25
VCC (V)
4061 G10
0
25
50
TEMPERATURE (°C)
75
Recharge Threshold Voltage vs
Temperature
Charge Current vs Supply Voltage
1000
104
RPROG = 1.25k
4.16
VCC = 5V
VBAT = 4V
C/5 = 5V
RPROG = 10k
ONSET OF THERMAL
REGULATION
102
100
4061 G12
4061 G11
Charge Current vs Ambient
Temperature with Thermal
Regulation
800
VCC = 4.3V
1.4
1.3
CTIMER = 0.1µF
–25
VCC = 8V
1.5
4.14
400
VRECHARGE (V)
IBAT (mA)
RPROG = 2k
VCC = 8V
4.10
100
VCC = 4.3V
4.08
98
200
4.06
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
96
125
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
4.04
–50
8.0
VCC (V)
4061 G13
Power FET “ON” Resistance vs
Temperature
Undervoltage Lockout Voltage vs
Temperature
500
VCC = 4V
IBAT = 200mA
–25
0
25
50
TEMPERATURE (°C)
75
100
4061 G15
4061 G14
Charge Current vs Battery Voltage
3.900
900
3.875
800
450
700
3.850
600
350
3.800
3.775
300
250
–50
IBAT (mA)
3.825
400
VUV (V)
IBAT (mA)
4.12
600
–25
0
25
50
TEMPERATURE (°C)
75
100
4061 G16
500
400
300
3.750
200
3.725
100
3.700
–50
0
–25
50
25
0
TEMPERATURE (°C)
75
100
4061 G17
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
VBAT (V)
4061 G18
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TYPICAL PERFOR A CE CHARACTERISTICS
⎯E⎯N Pin Pulldown Resistance vs
Temperature
⎯C⎯/⎯5 Pin Pulldown Resistance vs
Temperature
⎯E⎯N Pin Threshold Voltage
(On-to-Off) vs Temperature
4.0
4.0
900
VCC = 5V
3.5
3.5
3.0
3.0
2.5
2.5
850
VEN (mV)
800
750
700
2.0
2.0
1.5
–50
–25
50
25
0
TEMPERATURE (°C)
1.5
–50
100
75
650
–25
50
25
0
TEMPERATURE (°C)
4061 G19
0
25
50
TEMPERATURE (°C)
–25
⎯A⎯C⎯P⎯R Pin I-V Curve
70
VCC = 5V
160
VCC = 5V
VBAT = 4V
EN = VCC
850
60
800
50
140
TA = – 40°C
700
30
650
20
IACPR (mA)
ICC (µA)
VC/5 (mV)
120
40
100
4061 G21
Shutdown Supply Current vs
Temperature and VCC
750
75
4061 G20
⎯C⎯/⎯5 Pin Threshold Voltage
(High-to-Low) vs Temperature
900
600
–50
100
75
VCC = 8V
TA = 25°C
TA = 90°C
100
80
60
40
VCC = 5V
20
VCC = 4.3V
600
– 50
–25
50
25
0
TEMPERATURE (°C)
10
–50
100
75
–25
0
25
50
TEMPERATURE (°C)
75
0
1
2
4061 G23
⎯C⎯H⎯R⎯G Pin Output Low Voltage vs
Temperature
0.6
0.6
VCC = 5V
ICHRG = 5mA
0.5
⎯C⎯H⎯R⎯G Pin I-V Curve
160
VCC = 5V
IACPR = 5mA
VCC = 5V
VBAT = 4V
140
TA = – 40°C
120
ICHRG (mA)
0.4
VACPR (V)
VCHRG (V)
0.4
0.3
0.2
0.2
0.1
0.1
4
4061 G24
⎯A⎯C⎯P⎯R Pin Output Low Voltage vs
Temperature
0.3
3
VACPR (V)
4061 G22
0.5
0
100
TA = 25°C
TA = 90°C
100
80
60
40
0
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
4061 G25
0
–50
20
–25
50
25
0
TEMPERATURE (°C)
75
100
4061 G26
0
0
1
2
VCHRG (V)
3
4
4061 G27
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LTC4061
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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.
NTC (Pin 2): Input to the NTC (Negative Temperature Coefficient) Thermistor Temperature Monitoring Circuit. Under
normal operation, connect a thermistor from the NTC pin
to ground and a resistor of equal value from the NTC pin
to VCC. When the voltage at this pin drops below 0.35 •
VCC at hot temperatures or rises above 0.76 • VCC at cold,
charging is suspended, the internal timer is frozen and the
⎯C⎯H⎯R⎯G pin output will start to pulse at 1.5Hz. Pulling this
pin below 0.016 • VCC disables the NTC feature. There is
approximately 2°C of temperature hysteresis associated
with each of the input comparators thresholds.
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:
C TIMER
or
0.1µF
TIME (HOURS)
C TIMER = 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.
ACPR (Pin 4): Open-Drain Power Supply Present Status
Output. The power supply status indicator pin has two
states: pull-down 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 ⎯A⎯C⎯P⎯R pin. The state of this pin
is dependent on the value of VCC and BAT: it requires that
VCC is 190mV greater than VBAT and greater than VUVLO.
See Applications Information.
⎯ ⎯H⎯R⎯G (Pin 5): Open-Drain Charge Status Output. The
C
charge status indicator pin has three states: pull-down,
pulse at 1.5Hz or 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 ⎯C⎯H⎯R⎯G pin. The state of this pin
depends on the value of IDETECT as well as the termination method being used and the state of the NTC pin. See
Applications Information.
⎯C⎯/⎯5 (Pin 6): ⎯C⎯/⎯5 Enable Input. Used to control the amount
of current drawn from the 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.
⎯ (Pin 7): Charger Enable Input. A logic high on the E⎯ N
⎯ pin
E⎯ N
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 ⎯C⎯H⎯R⎯G 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 ⎯C⎯H⎯R⎯G
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
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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.
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 =
GND (Exposed Pad) (Pin 11): Ground. This pin is the back
of the exposed pad package and must be soldered to the
PCB copper for minimal thermal resistance.
VPROG
•1000
RPROG
W
BLOCK DIAGRA
10
VCC
+
4.1V
–
TO BAT
C1
1×
1×
1000×
–
NTC
2
BAT
+
1
MA
4
ACPR
HOT COLD DIS
ACPR
CA
–
5
VA
+
+
–
CHRG
1V
1.2V
STOP
0.2V
RECHRG
6
0.1V
C/5
C/5
LOGIC
3M
LOGIC
7
EN
EN
IDETECT
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
4061 BD
CTIMER
RDET
RPROG
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The LTC4061 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
LTC4061 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.
RPROG =
1000V
1000V
, 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
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 LTC4061 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 LTC4061
enters constant voltage mode and the charge current
decreases as the battery becomes fully charged.
The LTC4061 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 ⎯E⎯N 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:
SmartStart
When the LTC4061 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 LTC4061 enters charge mode and begins a
full charge cycle. If the BAT pin is above 4.1V, the LTC4061
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 LTC4061
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
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 LTC4061 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 LTC4061. 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.
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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 ⎯E⎯N 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 ⎯E⎯N 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 LTC4061
indicates the FAULT state by driving the ⎯C⎯H⎯R⎯G open-drain
output with a square wave. The duty cycle of this oscillation
is 50% and the frequency is set by CTIMER:
f CHRG =
0.1µF
• 6Hz
C TIMER
⎯ H
⎯ R
⎯ G
⎯ output exhibits a pulsing
A LED driven by the C
pattern, indicating to the user that the battery needs
replacing. To exit the FAULT state, the charger must be
restarted either by toggling the ⎯E⎯N input or removing and
reapplying power to VCC.
Charge Status Output (⎯C⎯H⎯R⎯G)
The charge status indicator pin has three states: pull-down,
pulse at 1.5Hz or 6Hz and high impedance. In the pull-down
state, an NMOS transistor pulls down on the ⎯C⎯H⎯R⎯G pin
capable of sinking up to 10mA. A pull-down state indicates
that the LTC4061 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 ⎯C⎯H⎯R⎯G indicates
that the LTC4061 is not charging.
Smart Pulsing Error Feature
LTC4061 has two different pulsing states at ⎯C⎯H⎯R⎯G pulldown pin:
1) 6Hz (50% duty cycle) due to defective battery detection (see Trickle-Charge and Defective Battery Detection
section);
2) 1.5Hz (25% duty cycle if in time termination, 50% duty
cycle if in charge current or user termination) due to NTC
out-of-temperature condition.
NTC Thermistor (NTC)
The temperature of the battery is measured by placing
a negative temperature coefficient (NTC) thermistor
close to the battery pack. The NTC circuitry is shown in
Figure 1. To use this feature, connect the NTC thermistor,
RNTC, between the NTC pin and ground and a resistor,
RNOM, from the NTC pin to VCC. RNOM should be a 1%
resistor with a value equal to the value of the chosen
NTC thermistor at 25°C (this value is 100kΩ for a Vishay
NTHS0603N01N1003J thermistor). The LTC4061 goes
into hold mode when the resistance, RHOT, of the NTC
thermistor drops to 0.53 times the value of RNOM or approximately 53kΩ, which corresponds to approximately
40°C. Hold mode freezes the timer and stops the charge
cycle until the thermistor indicates a return to a valid temperature. As the temperature drops, the resistance of the
NTC thermistor rises. The LTC4061 is designed to go into
hold mode when the value of the NTC thermistor increases
to 3.26 times the value of RNOM. This resistance is RCOLD.
For a Vishay NTHS0603N01N1003J thermistor, this value
is 326kΩ, which corresponds to approximately 0°C. The
hot and cold comparators each have approximately 2°C
of hysteresis to prevent oscillation about the trip point.
Grounding the NTC pin disables the NTC function. For more
details refer to the Application Information section.
1 The Defective Battery Detection feature is only available when time termination is being used.
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0.76 • VCC
VCC
–
TOO COLD
+
RNOM
NTC
2
0.35 • VCC
+
TOO HOT
–
RNTC
+
ENABLE
0.016 • VCC
–
LTC4061
4061 F01
Figure 1. NTC Circuit Information
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Programming Charge Termination
Charge Time Termination
The LTC4061 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.
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) =
0.1µF
• 3 HOURS
C TIMER
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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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 ⎯C⎯H⎯R⎯G 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 ⎯C⎯H⎯R⎯G output is in its pull-down state. When
the charger enters constant voltage mode operation and
the charge current falls below IDETECT, the ⎯C⎯H⎯R⎯G output
becomes high impedance, indicating that the battery is
almost fully charged. The ⎯C⎯H⎯R⎯G output will also become
high impedance once the charge time elapses. If the IDET
pin is not connected, the ⎯C⎯H⎯R⎯G 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 ⎯C⎯H⎯R⎯G output turns off the
LED. This indicates to the user that the battery is almost
fully charged and ready to use. The LTC4061 continues
to charge the battery until the internal timer reaches 3
hours (as set by CTIMER). During recharge cycles, the
LTC4061 charges the battery until the internal timer reaches
500mA
VIN
VCC
BAT
C/5 LTC4061
CHRG
PROG
RPROG
2k
IDET
RDET
1k
+
TIMER
GND
CTIMER
0.1µF
4061 F02
Figure 2. Time Termination Mode.
The Charge Cycle Ends After 3 Hours.
1.5 hours. Figure 3 describes the operation of the LTC4061
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 1ms),
charging is terminated.
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
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.
The ⎯C⎯H⎯R⎯G 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 LTC4061 charger
when charge current termination is used.
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 ⎯E⎯N pin.
The IDET pin programs the behavior of the ⎯C⎯H⎯R⎯G output in
the same manner as when using charge time termination.
If the IDET pin is not connected, the ⎯C⎯H⎯R⎯G 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 LTC4061 automatically begins charging,
regardless of the battery voltage. Figure 5 describes
charger operation when user-selectable charge termination is used.
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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
4061 F03
Figure 3. State Diagram of a Charge Cycle
Using Charge Time Termination
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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
BAT < 4.1V
IBAT < IDETECT
IN VOLTAGE MODE
STANDBY MODE
NO CHARGE CURRENT
BAT > 4.1V
EN = 5V
OR
UVLO CONDITION
CHRG STATE: Hi-Z
4061 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
4061 F05
EN = 5V
OR
UVLO CONDITION
Figure 5. State Diagram of a Charge Cycle
Using User-Selectable Termination
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Programming C/10 Current Detection/Termination
Power Dissipation
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.
When designing the battery charger circuit, it is not necessary to design for worst-case power dissipation scenarios
because the LTC4061 automatically reduces the charge
current during high power conditions. The conditions
that cause the LTC4061 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:
500mA
VIN
VCC
BAT
C/5 LTC4061
PROG
RPROG
2k
IDET
RDET
2k
+
TIMER
GND
PD = (VCC – VBAT) • IBAT
500mA
VIN
VCC
BAT
C/5 LTC4061
PROG
RPROG
1k
IDET
+
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
TIMER
GND
4061 F06
Figure 6. Two Circuits That Charge at 500mA
Full-Scale Current and Terminate at 50mA
When PROG and IDET are connected in this way, the fullscale charge current, ICHG, is programmed with a different
equation:
500V
500V
RPROG =
, ICHG =
ICHG
RPROG
TA = 105°C – (VCC – VBAT) • IBAT • θJA
Example: An LTC4061 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 LTC4061 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
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.
The LTC4061 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
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It is important to remember that LTC4061 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.
Thermistors
The LTC4061 NTC comparator trip points were designed
to work with thermistors whose resistance-temperature
characteristics follow Vishay Dale’s “R-T Curve 1.” The
Vishay NTHS0603N01N1003J is an example of such a
thermistor. However, Vishay Dale has many thermistor
products that follow the “R-T Curve 1” characteristic in a
variety of sizes. Furthermore, any thermistor whose ratio
of RCOLD to RHOT is about 6 also works (Vishay Dale R-T
Curve 1 shows a ratio of RCOLD to RHOT of 3.266/0.5325
= 6.13).
Power conscious designers may want to use thermistors
whose room temperature value is greater than 10kΩ.
Vishay Dale has a number of values of thermistor from
10kΩ to 100kΩ that follow the “R-T Curve 1.” Using different R-T curves, such as Vishay Dale “R-T Curve 2,” is
also possible. This curve, combined with LTC4061 internal
thresholds, gives temperature trip points of approximately
0°C (falling) and 40°C (rising), a delta of 40°C. This delta in
temperature can be moved in either direction by changing
the value of RNOM with respect to RNTC. Increasing RNOM
moves both trip points to lower temperatures. Likewise
a decrease in RNOM with respect to RNTC moves the trip
points to higher temperatures. To calculate RNOM for a shift
to lower temperatures, use the following equation:
RNOM =
RCOLD
• RNTC at 25°C
3.266
where RCOLD is the resistance ratio of RNTC at the desired
cold temperature trip point. If you want to shift the trip points
to higher temperatures, use the following equations:
RNOM =
RHOT
• RNTC at 25°C
0.5325
where RHOT is the resistance ratio of RNTC at the desired
hot temperature trip point.
Here is an example using 10kΩ R-T Curve 2 thermistor
from Vishay Dale. The difference between the trip points
is 40°C, from before, and we want the cold trip point to
be 0°C, which would put the hot trip point at 40°C. The
RNOM needed is calculated as follows:
RCOLD
• RNTC at 25°C
3.266
2.816
=
• 10kΩ = 8.62kΩ
3.266
RNOM =
The nearest 1% value for RNOM is 8.66kΩ. This is the
value used to bias the NTC thermistor to get cold and hot
trip points of approximately 0°C and 40°C respectively.
To extend the delta between the cold and hot trip points, a
resistor, R1, can be added in series with RNTC. The values
of the resistors are calculated as follows:
RCOLD – RHOT
3.266 – 0.5325
0.5325
⎛
⎞
R1 = ⎜
⎟ • (RCOLD – RHOT ) – RHOT
⎝ 3.266 − 0.5325⎠
RNOM =
where RNOM is the value of the bias resistor, RHOT and
RCOLD are the values of RNTC at the desired temperature
trip points. Continuing the example from before with a
desired hot trip point of 50°C:
RCOLD – RHOT 10k • (2.816 – 0.4086)
=
3.266 – 0.5325
3.266 – 0.5325
= 8.8kΩ, 8.87k is the nearest 1% value.
RNOM =
0.5325
⎛
⎞
R1 = 10k • ⎜
⎟
⎝ 3.266 – 0.5325⎠
• (2.816 – 0.4086) – 0.4086
= 604Ω, 604 is the nearest 1% value.
The final solution is RNOM = 8.87kΩ, R1 = 604Ω and
RNTC = 10kΩ at 25°C.
NTC Trip Point Error
When a 1% resistor is used for RHOT, the major error
in the 40°C trip point is determined by the tolerance of
the NTC thermistor. A typical 100kΩ NTC thermistor has
±10% tolerance. By looking up the temperature coefficient of the thermistor at 40°C, the tolerance error can
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be calculated in degrees centigrade. Consider the Vishay
NTHS0603N01N1003J thermistor, which has a temperature coefficient of –4%/°C at 40°C. Dividing the tolerance
by the temperature coefficient, ±5%/(4%/°C) = ±1.25°C,
gives the temperature error of the hot trip point.
The cold trip point error depends on the tolerance of the
NTC thermistor and the degree to which the ratio of its
value at 0°C and its value at 40°C varies from 6.14 to 1.
Therefore, the cold trip point error can be calculated using the tolerance, TOL, the temperature coefficient of the
thermistor at 0°C, TC (in %/°C), the value of the thermistor
at 0°C, RCOLD, and the value of the thermistor at 40°C,
RHOT. The formula is:
⎛ 1 + TOL RCOLD ⎞
•
– 1⎟ • 100
⎜
⎝ 6.14 RHOT
⎠
Temperature Error (°C ) =
TC
For example, the Vishay NTHS0603N01N1003J thermistor
with a tolerance of ±5%, TC of -5%/°C and RCOLD/ RHOT
of 6.13, has a cold trip point error of:
⎛ 1 + 0.05
⎞
• 6.13 – 1⎟ • 100
⎜
⎝ 6.14
⎠
Temperature Error (°C ) =
–5
= – 0.95°C, 1.05°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 LTC4061 package is properly soldered to
the PC board ground. Correctly soldered to a 2500mm2
double sided 1oz copper board, the LTC4061 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 LTC4061 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 multi-layer
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 LTC4061 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
voltage 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
LTC4061
VIN
VCC
4061 F07
Figure 7. Low Loss Input Reverse Polarity Protection
USB and Wall Adapter Power
The LTC4061 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
4061fa
17
LTC4061
U
W
U U
APPLICATIO S I FOR ATIO
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.
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.
5V WALL
ADAPTER
ICHG = 800mA
USB POWER
ICHG = 500mA
D1
VCC
MP1
SYSTEM
LOAD
BAT
LTC4061
IDET
C/5
+
PROG
Li-Ion
BATTERY
3.3k
1k
MN1
2k
1.25k
4061 F08
Figure 8. Combining Wall Adapter and USB Power
4061fa
18
LTC4061
U
PACKAGE DESCRIPTIO
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699)
R = 0.115
TYP
6
0.38 ± 0.10
10
0.675 ±0.05
3.50 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
3.00 ±0.10
(4 SIDES)
PACKAGE
OUTLINE
1.65 ± 0.10
(2 SIDES)
PIN 1
TOP MARK
(SEE NOTE 6)
(DD10) DFN 1103
5
0.25 ± 0.05
0.200 REF
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
1
0.75 ±0.05
0.00 – 0.05
0.25 ± 0.05
0.50 BSC
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
4061fa
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
LTC4061
U
TYPICAL APPLICATIO S
Full-Featured Li-Ion Charger
(Using Time Termination)
USB/Wall Adapter Power Li-Ion Charger
(Using Charge Current Termination)
VIN
5V
1µF
5V
WALL ADAPTER
1k
1k
5
0.1µF
VCC
CHRG
BAT
800mA
1
6
C/5
3
TIMER
9
4
ACPR
PROG
LTC4061
1.25k
2
8
NTC
IDET
GND
619Ω
11
10
USB
POWER
10
BAT
VCC
1
+
Li-Ion
CELL
LTC4061
1µF
6
9
µC
C/5
PROG
VIN
+
100k
3
SINGLE CELL
Li-Ion BATTERY
1k
IDET
TIMER
GND
11
100k
NTC
8
2k
2.5k
4061 TA03
4061 TA02
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PART NUMBER
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Power Management
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ThinSOT Package
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ThinSOT Package
95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.8V, IQ = 60µA, ISD < 1µA,
MS Package
95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 2.5V, IQ = 25µA, ISD < 1µA,
MS Package
2-Channel Ideal Diode ORing, Low Forward ON Resistance, Low Regulated
Forward Voltage, 2.5V ≤ VIN ≤ 5.5V
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
4061fa
20
Linear Technology Corporation
LT/TP 0305 1K REV A • PRINTED IN USA
FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2004
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
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