FEATURES
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LTC4006
4A, High Efficiency,
Standalone Li-Ion
Battery Charger
DESCRIPTIO
The LTC
®
4006 is a complete constant-current/constant-
voltage charger controller for 2-, 3- or 4-cell lithium bat-
teries in a small package using few external components.
The PWM controller is a synchronous, quasi-constant fre-
quency, constant off-time architecture that will not gener-
ate audible noise even when using ceramic capacitors.
The LTC4006 is available in 8.4V, 12.6V and 16.8V versions
with
±0.8%
voltage accuracy. Charging current is program-
mable with a single sense resistor to
±4%
typical accuracy.
Charging current can be monitored as a representative
voltage at the I
MON
pin. A timer, programmed by an external
resistor, sets the total charge time or is reset to 25% of total
charge time after C/10 charging current is reached. Charg-
ing automatically resumes when the cell voltage falls below
3.9V/cell.
Fully discharged cells are automatically trickle charged at
10% of the programmed current until the cell voltage ex-
ceeds 2.5V/cell. Charging terminates if the low-battery
condition persists for more than 25% of the total charge
time.
The LTC4006 includes a thermistor sensor input that
suspends charging if an unsafe temperature condition is
detected and automatically resumes charging when the
battery temperature returns to within safe limits.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5723970.
Complete Charger Controller for 2-, 3- or 4-Cell
Lithium-Ion Batteries
High Conversion Efficiency: Up to 96%
Output Currents Exceeding 4A
±0.8%
Accurate Preset Voltages: 8.4V, 12.6V, 16.8V
Built-In Charge Termination with Automatic Restart
AC Adapter Current Limiting Maximizes Charge Rate*
Automatic Conditioning of Deeply Discharged
Batteries
Thermistor Input for Temperature Qualified Charging
Wide Input Voltage Range: 6V to 28V
0.5V Dropout Voltage; Maximum Duty Cycle: 98%
Programmable Charge Current:
±4%
Accuracy
Indicator Outputs for Charging, C/10 Current
Detection and AC Adapter Present
Charging Current Monitor Output
16-Pin Narrow SSOP Package
APPLICATIO S
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Notebook Computers
Portable Instruments
Battery-Backup Systems
Standalone Li-Ion Chargers
TYPICAL APPLICATIO
DCIN
0V TO 28V
3A
V
LOGIC
4A Li-Ion Battery Charger
INPUT SWITCH
0.1µF
100k
INFET
LTC4006
CLP
CHG
DCIN
ACP/SHDN
32.4k
I
MON
NTC
CLN
TGATE
BGATE
PGND
CSP
BAT
4006 TA01
5k
15nF
0.033Ω
TO SYSTEM LOAD
20µF
10µH
CHG
ACP
CHARGING
CURRENT MONITOR
0.0047µF
THERMISTOR
10k
NTC
0.47µF
309k
TIMING
RESISTOR
(~2 HOURS)
6k
0.12µF
R
T
I
TH
GND
U
U
U
0.025Ω
BATTERY
20µF
4006fa
1
LTC4006
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
DCIN
CHG
ACP/SHDN
R
T
GND
NTC
I
TH
I
MON
1
2
3
4
5
6
7
8
16 INFET
15 BGATE
14 PGND
13 TGATE
12 CLN
11 CLP
10 BAT
9
CSP
Voltage from DCIN, CLP, CLN, TGATE, INFET,
ACP/SHDN, CHG to GND ....................... + 32V to – 0.3V
Voltage from CLP to CLN .....................................
±0.3V
CSP, BAT to GND ................................... +28V to – 0.3V
R
T
to GND ................................................. +7V to – 0.3V
NTC ........................................................ +10V to – 0.3V
Operating Ambient Temperature Range
(Note 4) ............................................. – 40°C to 85°C
Operating Junction Temperature ......... – 40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC4006EGN-2
LTC4006EGN-4
LTC4006EGN-6
GN PART MARKING
40062
40064
40066
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
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
SYMBOL
I
DCIN
V
TOL
PARAMETER
DCIN Operating Range
DCIN Operating Current
Voltage Accuracy
The
●
denotes specifications which apply over the full operating
temperature range (Note 4), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT
= 12V unless otherwise noted.
CONDITIONS
Sum of Current from CLP, CLN, DCIN
(Note 2)
LTC4006-6
LTC4006-6
LTC4006-2
LTC4006-2
LTC4006-4
LTC4006-4
V
CSP
– V
BAT
Target = 100mV
V
BAT
= 11.5V (LTC4006-2)
V
BAT
= 7.6V (LTC4006-6)
V
BAT
= 12V (LTC4006-4)
V
BAT
< 6V, V
CSP
– V
BAT
Target = 10mV
6V
≤
V
BAT
≤
V
LOBAT
,
V
CSP
– V
BAT
Target = 10mV
T
TOL
Shutdown
Battery Leakage Current
DCIN = 0V
DCIN = 0V
DCIN = 20V, V
SHDN
= 0V, V
BAT
= 12V
DCIN Rising, V
BAT
= 0V
V
SHDN
= 0V, Sum of Current from CLP,
CLN, DCIN
●
●
●
●
MIN
6
TYP
3
MAX
28
5
8.467
8.484
12.700
12.726
16.935
16.968
4
5
UNITS
V
mA
V
V
V
V
V
V
%
%
●
●
●
●
8.333
8.316
12.499
12.474
16.665
16.632
–4
–5
8.4
8.4
12.6
12.6
16.8
16.8
I
TOL
Current Accuracy (Note 3)
– 60
– 40
●
60
40
15
20
25
0
4.7
2
35
45
10
5.5
2.5
3
Termination Timer Accuracy
R
RT
= 270k
–15
–10
4.2
1
UVLO
Undervoltage Lockout Threshold
Shutdown Threshold at ACP/SHDN
DCIN Current in Shutdown
Current Sense Amplifier, CA1
Input Bias Current Into BAT Pin
CMSL
CMSH
CA1/I
1
Input Common Mode Low
CA1/I
1
Input Common Mode High
●
●
11.67
0
V
CLN
– 0.2
2
U
W
U
U
W W
W
%
%
%
µA
µA
µA
V
V
mA
µA
V
V
4006fa
LTC4006
ELECTRICAL CHARACTERISTICS
SYMBOL
I
TMAX
I
TREV
PARAMETER
Maximum Current Sense Threshold (V
CSP
– V
BAT
)
Reverse Current Threshold (V
CSP
– V
BAT
)
Transconductance
Source Current
Sink Current
Current Limit Amplifier
Transconductance
V
CLP
I
CLP
Current Limit Threshold
CLP Input Bias Current
Transconductance
Sink Current
OVSD
Overvoltage Shutdown Threshold as a Percent
of Programmed Charger Voltage
DCIN Detection Threshold (V
DCIN
– V
CLN
)
Forward Regulation Voltage (V
DCIN
– V
CLN
)
Reverse Voltage Turn-Off Voltage (V
DCIN
– V
CLN
)
INFET “On” Clamping Voltage (V
DCIN
– V
INFET
)
INFET “Off” Clamping Voltage (V
DCIN
– V
INFET
)
Thermistor
NTCVR
Reference Voltage During Sample Time
High Threshold
Low Threshold
Thermistor Disable Current
Indicator Outputs (ACP/SHDN, CHG)
C10TOL
LBTOL
C/10 Indicator Accuracy
LOBAT Threshold Accuracy
Current Comparators I
CMP
and I
REV
The
●
denotes specifications which apply over the full operating
temperature range (Note 4), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT
= 12V unless otherwise noted.
CONDITIONS
V
ITH
= 2.5V
●
MIN
140
TYP
165
– 30
1
MAX
200
UNITS
mV
mV
mmho
µA
µA
mmho
Current Sense Amplifier, CA2
Measured at I
TH
, V
ITH
= 1.4V
Measured at I
TH
, V
ITH
= 1.4V
– 40
40
1.5
●
93
100
100
1
107
mV
nA
mmho
µA
Voltage Error Amplifier, EA
Measured at I
TH
, V
ITH
= 1.4V
●
36
102
107
110
%
Input P-Channel FET Driver (INFET)
DCIN Voltage Ramping Up
from V
CLN
– 0.1V
DCIN Voltage Ramping Down
I
INFET
= 1µA
I
INFET
= – 25µA
4.5
V
NTC
Rising
V
NTC
Falling
V
NTC
≤
10V
Voltage Falling at PROG
LTC4006-6
LTC4006-2
LTC4006-4
LTC4006-6
LTC4006-2
LTC4006-4
I
OL
= 100µA
I
OH
= –1µA
V = 0V
V
OH
= 3V
V
OH
= 3V
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
0
0.17
25
0.25
50
6.5
0.25
V
mV
mV
V
V
V
– 60
5
– 25
5.8
NTCVR
• 0.48
NTCVR
• 0.115
NTCVR
• 0.5
NTCVR
• 0.125
NTCVR
• 0.52
NTCVR
• 0.135
10
V
V
µA
V
V
V
V
V
V
V
V
V
µA
0.375
4.70
7.27
9.70
7.5
11.35
15.15
2.7
0.400
4.93
7.5
10
7.8
11.7
15.6
0.425
5.14
7.71
10.28
7.96
11.94
15.92
0.5
RESTART Threshold Accuracy
V
OL
V
OH
I
PO
IC10
I
OFF
Low Logic Level of ACP/SHDN, CHG
High Logic Level of ACP/SHDN
Pull-Up Current on ACP/SHDN
C/10 Indicator Sink Current from CHG
Off State Leakage Current of CHG
Timer Defeat Threshold at CHG
–10
15
–1
1
25
38
1
µA
µA
V
4006fa
3
LTC4006
ELECTRICAL CHARACTERISTICS
SYMBOL
Oscillator
f
OSC
f
MIN
DC
MAX
Regulator Switching Frequency
Regulator Switching Frequency in Drop Out
Regulator Maximum Duty Cycle
V
TGATE
High (V
CLN
– V
TGATE
)
V
BGATE
High
V
TGATE
Low (V
CLN
– V
TGATE
)
V
BGATE
Low
TGTR
TGTF
BGTR
BGTF
TGATE Transition Time
TGATE Rise Time
TGATE Fall Time
BGATE Transition Time
BGATE Rise Time
BGATE Fall Time
V
TGATE
at Shutdown (V
CLN
– V
TGATE
)
V
BGATE
at Shutdown
PARAMETER
The
●
denotes specifications which apply over the full operating
temperature range (Note 4), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT
= 12V unless otherwise noted.
CONDITIONS
MIN
255
Duty Cycle
≥
98%
V
CSP
= V
BAT
I
TGATE
= –1mA
C
LOAD
= 3000pF
C
LOAD
= 3000pF
I
BGATE
= 1mA
C
LOAD
= 3000pF, 10% to 90%
C
LOAD
= 3000pF, 10% to 90%
C
LOAD
= 3000pF, 10% to 90%
C
LOAD
= 3000pF, 10% to 90%
I
TGATE
= –1µA, DCIN = 0V, CLN = 12V
I
BGATE
= 1µA, DCIN = 0V, CLN = 12V
50
50
40
40
4.5
4.5
5.6
5.6
20
98
TYP
300
25
99
50
10
10
50
110
100
90
80
100
100
MAX
345
UNITS
kHz
kHz
%
mV
V
V
mV
ns
ns
ns
ns
mV
mV
Gate Drivers (TGATE, BGATE)
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:
See Test Circuit
Note 3:
Does not include tolerance of current sense resistor.
Note 4:
The LTC4006E 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.
TYPICAL PERFOR A CE CHARACTERISTICS
INFET Response Time to
Reverse Current
V
gs
OF PFET (2V/DIV)
V
gs
= 0
OUTPUT VOLTAGE ERROR (%)
0
–0.5
–1.0
PWM FREQUENCY (kHz)
–1.5
–2.0
–2.5
–3.0
–3.5
–4.0
–4.5 DCIN = 20V
V
BAT
= 12.6V
–5.0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT CURRENT (A)
4006 G02
V
s
OF PFET (5V/DIV)
V
s
= 0V
I
d
(REVERSE) OF
PFET (5A/DIV)
I
d
= 0A
1.25µs/DIV
TEST PERFORMED ON DEMOBOARD
LTC4006-2
V
IN
= 15VDC
CHARGER = ON
INFET = 1/2 Si4925DY
I
CHARGE
= <10mA
4006 G01
4
U W
V
OUT
vs I
OUT
350
300
250
200
150
PWM Frequency vs Duty Cycle
PROGRAMMED CURRENT = 10%
100
50
0
0
DCIN = 15V
DCIN = 20V
DCIN = 24V
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
DUTY CYCLE (V
OUT
/V
IN
)
4006 G03
4006fa
LTC4006
TYPICAL PERFOR A CE CHARACTERISTICS
Disconnect/Reconnect Battery
(Load Dump)
40
BATTERY LEAKAGE CURRENT (µA)
V
FLOAT
1V/(DIV)
LOAD
STATE
DISCONNECT
LOAD CURRENT = 1A, 2A, 3A
DCIN = 20V
LTC4006-2
4006 G04
Efficiency at 19VDC V
IN
100
LTC4006-4
95
LTC4006-2
95
EFFICIENCY (%)
EFFICIENCY (%)
90
85
80
75
0.50
1.00
1.50
2.00
2.50
CHARGING CURRENT (A)
3.00
4006 G07
PI FU CTIO S
DCIN (Pin 1):
External DC Power Source Input. Bypass
this pin with at least 0.01µF. See Applications Information
section.
CHG (Pin 2):
Open-Drain Charge Status Output. When the
battery is being charged, the CHG pin is pulled low by an
internal N-channel MOSFET. When the charge current
drops below 10% of programmed current, the N-channel
MOSFET turns off and a 25µA current source is connected
from the CHG pin to GND. When the timer runs out or the
input supply is removed, the current source will be discon-
nected and the CHG pin is forced into a high impedance
state. A pull-up resistor is required. The timer function is
defeated by forcing this pin below 1V (or connecting it to
GND).
ACP/SHDN (Pin 3):
Open-Drain Output used to indicate if
the AC adapter voltage is adequate for charging. Active
high digital output. Internal 10µA pull-up to 3.5V. The
charger can also be inhibited by pulling this pin below 1V.
Reset the charger by pulsing the pin low for a minimum of
0.1µs.
4006fa
U W
3A STEP
1A STEP
Battery Leakage Current vs
Battery Voltage
VDCIN = 0V
35
30
25
20
15
10
5
0
0
5
10
15
20
BATTERY VOLTAGE (V)
25
30
4006 G05
1A STEP
3A STEP
RECONNECT
LTC4006-2 Efficiency with
15VDC V
IN
100
90
85
80
75
0.50
1.00
1.50
2.00
2.50
CHARGING CURRENT (A)
3.00
4006 G08
U
U
U
5
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