Final Electrical Specifications
LTC4007
4A, High Efficiency,
Standalone Li Battery Charger
FEATURES
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DESCRIPTION
January 2003
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Complete Charger Controller for 3- or 4-Cell
Lithium-Ion Batteries
High Conversion Efficiency: Up to 96%
Output Currents Exceeding 4A
±0.8%
Charging Voltage Accuracy
Built-In Charge Termination for Li-Ion Batteries
AC Adapter Current Limiting Maximizes Charge Rate*
Thermistor Input for Temperature Qualified Charging
Wide Input Voltage Range: 6V to 28V
0.5V Dropout Voltage; Maximum Duty Cycle: 98%
Programmable Charge Current:
±5%
Accuracy
Indicator Outputs for Charging, C/10 Current
Detection, AC Adapter Present, Low Battery, Input
Current Limiting and Faults
Charging Current Monitor Output
Available in a 24-Pin Narrow SSOP Package
The LTC
®
4007 is a complete constant-current/constant-
voltage charger controller for 3- or 4-cell lithium-ion
batteries. The PWM controller uses a synchronous, quasi-
constant frequency, constant off-time architecture that
will not generate audible noise even when using ceramic
capacitors. Charging current is programmable to
±5%
accuracy using a programming resistor. Charging current
can also be monitored as a voltage across the program-
ming resistor.
The output float voltage is pin programmed for cell count
(3 cells or 4 cells) and chemistry (4.2V/4.1V). A timer,
programmed by an external resistor, sets the total charge
time. Charging is automatically restarted when cell voltage
falls below 3.9V/cell.
LTC4007 includes a thermistor input, which suspends
charging if an unsafe temperature condition is detected. If
the cell voltage is less than 2.5V, a low-battery indicator
asserts and can be used to program a trickle charge cur-
rent to safely charge depleted batteries. The FAULT pin is
also asserted and charging terminates if the low-battery
condition persists for more than 1/4 of the total charge time.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*U.S. Patent No. 5,723,970
APPLICATIO S
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Notebook Computers
Portable Instruments
Battery-Backup Systems
Standalone Li-Ion Chargers
TYPICAL APPLICATIO
DCIN
0V TO 28V
12.6V, 4A Li-Ion Battery Charger
INPUT SWITCH
0.1µF
4.9k
V
LOGIC
100k
LOBAT
I
CL
ACP
SHDN
FAULT
CHG
FLAG
32.4k
100k
100k
3C4C
CHEM
LOBAT
I
CL
ACP
SHDN
FAULT
CHG
FLAG
NTC
THERMISTOR
10k
NTC
R
T
0.47µF
309k
TIMING RESISTOR
(~2 HOURS)
DCIN
INFET
CLP
20µF
Q1
Q2
10µH
0.025Ω
Li-Ion
BATTERY
15nF
0.025Ω
SYSTEM
LOAD
LTC4007 CLN
TGATE
BGATE
PGND
CSP
BAT
PROG
ITH
GND
6.04k
0.12µF
0.0047µF
26.7k
3.01k
3.01k
Q1: Si4431DY
Q2: FDC6459
4007 TA01
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
U
U
20µF
CHARGING
CURRENT
MONITOR
4007i
1
LTC4007
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
DCIN
CHG
ACP
R
T
FAULT
GND
3C4C
LOBAT
NTC
1
2
3
4
5
6
7
8
9
24 SHDN
23 INFET
22 BGATE
21 PGND
20 TGATE
19 CLN
18 CLP
17 FLAG
16 CHEM
15 BAT
14 CSP
13 I
CL
Voltage from DCIN, CLP, CLN to GND ....... + 32V/– 0.3V
PGND with Respect to GND .................................
±0.3V
CSP, BAT to GND ....................................... +28V/– 0.3V
CHEM, 3C4C, R
T
to GND .............................. +7V/– 0.3V
NTC ............................................................ +10V/– 0.3V
ACP, SHDN, CHG, FLAG,
FAULT, LOBAT, I
CL ..............................................
+ 32V/– 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
LTC4007EGN
ITH 10
PROG 11
NC 12
GN PACKAGE
24-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 90°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
I
Q
V
TOL
I
TOL
PARAMETER
DCIN Operating Range
Operating Current
Charge Voltage Accuracy
Charge Current Accuracy (Note 3)
The
q
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
Nominal Values: 12.3V, 12.6V, 16.4V, 16.8V
(Note 2)
q
V
CSP
– V
BAT
Target = 100mV
q
MIN
6
TYP
3
MAX
28
5
0.8
1.0
4
5
60
35
15
UNITS
V
mA
%
%
%
%
%
%
%
µA
µA
V
V
µA
mA
–0.8
–1.0
–4
–5
–60
–35
–15
15
–10
4.2
1
4.7
1.6
– 10
2
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
UVLO
Undervoltage Lockout Threshold
Shutdown Threshold at SHDN
SHDN Pin Current
Operating 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
q
q
Termination Timer Accuracy
R
RT
= 270k
DCIN = 0V
SHDN = 3V
DCIN Rising, V
BAT
= 0
q
q
q
q
q
30
10
5.5
2.5
3
V
SHDN
= 0V, Sum of Current from CLP,
CLN, DCIN
11.67
0
V
CLN
– 0.2
2
U
W
U
U
W W
W
µA
V
V
4007i
LTC4007
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, CHG, FLAG, LOBAT, I
CL
, FAULT
C10TOL
LBTOL
FLAG (C/10) Accuracy
LOBAT Threshold Accuracy
Current Comparators I
CMP
and I
REV
The
q
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
= 2.4V
q
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
1.4
q
93
100
100
1
107
mV
nA
mmho
µA
Voltage Error Amplifier, EA
Measured at I
TH
, V
ITH
= 1.4V
q
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
3C4C = 0V, CHEM = 0V
3C4C = 0V, CHEM = Open
3C4C = Open, CHEM = 0V
3C4C = Open, CHEM = Open
3C4C = 0V, CHEM = 0V
3C4C = 0V, CHEM = Open
3C4C = Open, CHEM = 0V
3C4C = Open, CHEM = Open
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
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
mV
0.375
7.10
7.27
9.46
9.70
11.13
11.40
14.84
15.20
83
0.397
7.32
7.50
9.76
10
11.42
11.70
15.23
15.60
93
0.420
7.52
7.71
10.10
10.28
11.65
11.94
15.54
15.92
1O5
RESTART Threshold Accuracy
I
CL
Threshold Accuracy
4007i
3
LTC4007
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OL
V
OH
I
OFF
I
PO
PARAMETER
Low Logic Level of ACP, CHG, FLAG, LOBAT,
I
CL
, FAULT
High Logic Level of CHG, LOBAT, I
CL
Off State Leakage Current of ACP, FLAG, FAULT
Pull-Up Current on CHG, LOBAT, I
CL
Timer Defeat Threshold at CHG
Programming Inputs (CHEM and 3C4C)
V
IH
V
IL
I
PI
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
High Logic Level
Low Logic Level
Pull-Up Current
The
q
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
I
OL
= 100µA
I
OH
= –1µA
V
OH
= 3V
V = 0V
1
q
q
q
q
MIN
TYP
MAX
0.5
UNITS
V
V
2.7
–1
–10
1
µA
µA
V
3.3
1
– 14
255
300
25
99
50
4.5
4.5
5.6
5.6
10
10
50
50
50
40
40
110
100
90
80
100
100
345
V
V
µA
kHz
kHz
%
mV
V
V
mV
ns
ns
ns
ns
mV
mV
V = 0V
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
20
98
Gate Drivers (TGATE, BGATE)
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
See Test Circuit.
Note 3:
Does not include tolerance of current sense resistor or current
programming resistor.
Note 4:
The LTC4007E 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.
4007i
4
LTC4007
PI FU CTIO S
DCIN (Pin 1):
External DC Power Source Input. Bypass
this pin with at least 0.01µF. See Applications Information.
CHG (Pin 2):
Charge Status Output. When the battery is
being charged, the CHG pin is pulled low by an internal
N-channel MOSFET. Internal 10µA pull-up to 3.5V. If
V
LOGIC
is greater than 3.3V, add an external pull-up. The
timer function can be defeated by forcing this pin below 1V
(or connecting it to GND).
ACP(Pin 3):
Open-Drain output to indicate if the AC
adapter voltage is adequate for charging. This pin is pulled
low by an internal N-channel MOSFET if DCIN is below
BAT. A pull-up resistor is required. The pin is capable of
sinking at least 100µA.
R
T
(Pin 4):
Timer Resistor. The timer period is set by
placing a resistor, R
RT
, to GND. This resistor is always
required.
The timer period is t
TIMER
= (1hour • R
RT
/154K).
FAULT (Pin 5):
Active low open-drain output that indi-
cates charger operation has stopped due to a low-battery
conditioning error, or that charger operation is suspended
due to the thermistor exceeding allowed values. A pull-up
resistor is required if this function is used. The pin is
capable of sinking at least 100µA.
GND (Pin 6):
Ground for Low Power Circuitry.
3C4C (Pin 7):
Select 3-cell or 4-cell float voltage by
connecting this pin to GND or open, respectively. Internal
14µA pull-up to 5.3V. This pin can also be driven with
open-collector/drain logic levels. High: 4 cell. Low: 3 cell.
LOBAT (Pin 8):
Low-Battery Indicator. Active low digital
output. Internal 10µA pull-up to 3.5V. If the battery
voltage is below 2.5V/cell (or 2.44V/cell for 4.1V chemis-
try batteries) LOBAT will be low. The pin is capable of
sinking at least 100µA. If V
LOGIC
is greater than 3.3V, add
an external pull-up.
NTC (Pin 9):
A thermistor network is connected from NTC
to GND. This pin determines if the battery temperature is
safe for charging. The charger and timer are suspended
and the FAULT pin is driven low if the thermistor indicates
a temperature that is unsafe for charging. The thermistor
function may be disabled with a 300k to 500k resistor from
DCIN to NTC.
ITH (Pin 10):
Control Signal of the Inner Loop of the
Current Mode PWM. Higher ITH voltage corresponds to
higher charging current in normal operation. A 6k resistor,
in series with a capacitor of at least 0.1µF to GND provides
loop compensation. Typical full-scale output current is
40µA. Nominal voltage range for this pin is 0V to 3V.
PROG (Pin 11):
Current Programming/Monitoring Input/
Output. An external resistor to GND programs the peak
charging current in conjunction with the current sensing
resistor. The voltage at this pin provides a linear indication
of charging current. Peak current is equivalent to 1.19V.
Zero current is approximately 0.3V. A capacitor from
PROG to ground is required to filter higher frequency
components. The maximum resistance to ground is 100k.
Values higher than 100k can cause the charger to shut
down.
NC (Pin 12):
No Connect.
I
CL
(Pin 13):
Input Current Limit Indicator. Active low
digital output. Internal 10µA pull-up to 3.5V. Pulled low if
the charger current is being reduced by the input current
limiting function. The pin is capable of sinking at least
100µA. If V
LOGIC
is greater than 3.3V, add an external
pull-up.
CSP (Pin 14):
Current Amplifier CA1 Input. The CSP and
BAT pins measure the voltage across the sense resistor,
R
SENSE
, to provide the instantaneous current signals re-
quired for both peak and average current mode operation.
U
U
U
4007i
5
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