LTC4064
Monolithic Linear Charger
for Back-Up Li-Ion Batteries
FEATURES
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DESCRIPTIO
■
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Preset 4V Charge Voltage with 1% Accuracy
Prolongs 4.2V Li-Ion Battery Lifetime
Automatic Recharge
Thermal Regulation Maximizes Charging Rate
without Risk of Overheating*
No MOSFET, Sense Resistor or Blocking Diode
Required
Programmable Charge Termination Timer
Thermistor Input for Temperature Qualified Charging
Programmable Charge Current with 7% Accuracy
C/10 Charge Current Detection Output
25µA Supply Current in Shutdown Mode
Charge Current Monitor Useful for Gas Gauging*
Charges Directly from USB Port
Tiny Thermally Enhanced 10-pin MSOP Package
The LTC4064 is a standalone linear charger optimized for
prolonging the life of 1-cell Li-ion batteries in battery back-
up applications. By charging to a float voltage of 4V
instead of 4.2V or 4.1V, the LTC4064 decelerates the aging
process and capacity degradation when the battery is
unused for long periods of time but must be in a ready
state.
An external capacitor programs a safety timer to terminate
the charge cycle while the charge current is set externally
with a single resistor. When the input supply is removed,
the LTC4064 automatically enters a low current sleep
mode, dropping the battery drain current to less than 3µA.
Additional safety features designed to maximize battery
lifetime and reliability include NTC temperature sensing
and low battery charge conditioning (trickle charging).
The IC contains an on-chip power MOSFET and eliminates
the need for an external sense resistor and blocking diode.
The LTC4064 also includes C/10 detection circuitry, AC
present logic, and fault detection circuitry.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*US Patent No. 6522118
APPLICATIO S
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File Servers, RAID Systems
Storage Products
Li-Ion Battery Back-Up
TYPICAL APPLICATIO
Standalone Back-Up Li-Ion Battery Charger
V
IN
= 5V
8
SHDN
4.7µF
2
V
CC
BAT
9
I
BAT
= 1A
V
FLOAT
= 4V
1-CELL
Li-Ion
BATTERY*
LTC4064
4
7
PROG
TIMER
GND
0.1µF
5, 11
NTC
6
1.5k
1%
4064TA01
*AN OUTPUT CAPACITOR MAY BE REQUIRED
DEPENDING ON BATTERY LEAD LENGTH
U
sn4064 4064fs
U
U
1
LTC4064
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CHRG
V
CC
FAULT
TIMER
GND
1
2
3
4
5
10
9
8
7
6
ACPR
BAT
SHDN
PROG
NTC
Input Supply Voltage (V
CC
) ..................................... 10V
BAT ......................................................................... 10V
NTC, SHDN, TIMER, PROG ............ –0.3V to V
CC
+ 0.3V
CHRG, FAULT, ACPR ................................ –0.3V to 10V
BAT Short-Circuit Duration .......................... Continuous
BAT Current (Note 2) ............................................. 1.3A
PROG Current (Note 2) ....................................... 1.3mA
Junction Temperature .......................................... 125°C
Operating Temperature Range (Note 3) ...–40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC4064EMSE
MSE PART MARKING
LTAHQ
11
MSE EXPOSED PAD PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 40°C/W (Note 4)
EXPOSED PAD IS GND, (PIN 11)
MUST BE SOLDERED TO PCB
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V
SYMBOL
V
CC
I
CC
PARAMETER
V
CC
Supply Voltage
V
CC
Supply Current
Charger On; Current Mode; R
PROG
= 30k (Note 5)
Shutdown Mode; V
SHDN
= 0V
Sleep Mode V
CC
< V
BAT
or V
CC
≤
4V
R
PROG
= 3k; Current Mode
R
PROG
= 15k; Current Mode
Shutdown Mode; V
SHDN
= 0V
Sleep Mode V
CC
< V
BAT
or V
CC
< (V
UV
–
∆V
UV
)
V
BAT
< 2V; R
PROG
= 3k
V
BAT
Rising
V
CC
Rising
SHDN Pin Voltage
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
●
●
●
●
●
●
●
MIN
4.25
TYP
1
25
25
MAX
6.5
2
50
50
4.04
535
107
±3
±3
65
UNITS
V
mA
µA
µA
V
mA
mA
µA
µA
mA
V
mV
V
FLOAT
I
BAT
V
BAT
Regulated Float Voltage
Battery Pin Current
3.96
465
93
4.00
500
100
±1
±1
50
2.48
100
4
200
I
TRIKL
V
TRIKL
∆V
TRIKL
V
UV
∆V
UV
V
MSD
V
ASD
Trickle Charge Current
Trickle Charge Trip Threshold Voltage
Trickle Charge Trip Hysteresis Voltage
V
CC
Undervoltage Lockout Voltage
V
CC
Undervoltage Lockout Hysteresis
Manual Shutdown Threshold Voltage
●
35
4.25
1.3
0.6
35
70
Automatic Shutdown Threshold Voltage (V
CC
- V
BAT
) High to Low
(V
CC
- V
BAT
) Low to High
sn4064 4064fs
2
U
V
mV
V
mV
mV
W
U
U
W W
W
LTC4064
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V
SYMBOL
V
PROG
I
CHRG
V
CHRG
V
ACPR
V
FAULT
I
C/10
t
TIMER
∆V
RECHRG
V
NTC-HOT
V
HOT-HYS
V
NTC-COLD
V
COLD-HYS
V
NTC-DIS
V
DIS-HYS
T
LIM
R
ON
PARAMETER
PROG Pin Voltage
CHRG Pin Weak Pulldown Current
CHRG Pin Output Low Voltage
ACPR Pin Output Low Voltage
FAULT Pin Output Low Voltage
End of Charge Indication Current Level
TIMER Accuracy
Recharge Threshold Voltage
NTC Pin Hot Threshold Voltage
NTC Pin Hot Hysteresis Voltage
NTC Pin Cold Threshold Voltage
NTC Pin Cold Hystersis Voltage
NTC Pin Disable Threshold Voltage
NTC Pin Disable Hystersis Voltage
Junction Temperature in
Constant-Temperature Mode
Power MOSFET “ON” Resistance
V
NTC
Rising
V
NTC
Rising
CONDITIONS
R
PROG
= 3k, I
PROG
= 500µA
V
CHRG
= 1V
I
CHRG
= 5mA
I
ACPR
= 5mA
I
FAULT
= 5mA
R
PROG
= 3k
C
TIMER
= 0.1µF
V
FLOAT
- V
RECHRG
, V
BAT
> V
TRIKL
Charge Termination Timer Expired
V
NTC
Falling
●
ELECTRICAL CHARACTERISTICS
MIN
15
TYP
1.5
30
0.35
0.35
0.35
MAX
50
0.6
0.6
0.6
56
135
UNITS
V
µA
V
V
V
mA
%
mV
V
mV
V
mV
mV
mV
°C
mΩ
44
65
50
10
100
2.5
80
4.375
80
100
10
105
375
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The Absolute Maximum BAT Current Rating of 1.3A is guaranteed
by design and current density calculations. The Absolute Maximum PROG
Current Rating is guaranteed to be 1/1000 of BAT current rating by design.
Note 3:
The LTC4064 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 4:
Failure to solder the exposed backside of the package to the PC
board will result in a thermal resistance much higher than 40°C/W.
Note 5:
Supply current includes PROG pin current (approximately 50µA)
but does not include any current delivered to the battery through the BAT
pin (approximately 50mA).
sn4064 4064fs
3
LTC4064
TYPICAL PERFOR A CE CHARACTERISTICS
Battery Regulation Voltage
vs Battery Charge Current
4.02
4.01
4.00
V
CC
= 5V
T
A
= 25°C
R
PROG
= 3k
V
BAT
(V)
V
BAT
(V)
3.96
3.94
3.92
3.90
V
CC
= 5V
R
PROG
= 3k
I
BAT
= 10mA
–25
0
25
50
75
TEMPERATURE (°C)
100
125
3.99
3.98
3.97
V
BAT
(V)
3.96
0
50 100 150 200 250 300 350 400 450 500
I
BAT
(mA)
4064 G01
Charge Current vs Input Voltage
600
500
400
T
A
= 25°C
I
BAT
(mA)
I
BAT
(mA)
I
BAT
(mA)
300
200
100
0
4.0
4.5
V
CC
(V)
5.0
Undervoltage Lockout Voltage
vs Temperature
4.05
4.04
4.03
4.02
I
CC
(µA)
4.00
3.99
3.98
3.97
3.96
3.95
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
15
10
5
0
–50 –25
V
CC
= 4.5V
V
MSD
(V)
V
UV
(V)
4.01
4
U W
4064 G04
Battery Regulation Voltage
vs Temperature
4.04
4.02
4.00
3.98
Battery Regulation Voltage
vs V
CC
4.010
4.008
4.006
4.004
4.002
4.000
3.998
3.996
3.994
3.992
3.990
4
4.5
5
5.5
V
CC
(V)
6
6.5
7
4064 G03
V
CC
= 5V
T
A
= 25°C
R
PROG
= 3k
I
BAT
= 10mA
3.88
3.86
–50
4064 G02
Charge Current vs Battery Voltage
550
500
450
400
350
300
250
200
150
100
50
0
5.5
Charge Current vs Ambient
Temperature with Thermal
Regulation
1000
900
800
700
600
500
400
300
200
100
V
CC
= 5V
V
BAT
= 3.5V
R
PROG
= 1.5k
–25
25
50
0
TEMPERATURE (°C)
75
100
4064 G06
V
CC
= 5V
T
A
= 25°C
R
PROG
= 3k
THERMAL CONTROL
LOOP IN OPERATION
0
0.5
1
1.5
2 2.5
V
BAT
(V)
3
3.5
4
4.5
0
–50
4064 G05
Shutdown Supply Current
vs Temperature and V
CC
30
25
20
1.30
Manual Shutdown Threshold
Voltage vs Temperature and V
CC
1.25
1.20
V
SHDN
= 0V
V
CC
= 6.5V
V
CC
= 5.5V
1.15
1.10
1.05
1.00
0.95
0.90
0.85
V
CC
= 5V
V
CC
= 6V
V
CC
= 5.5V
V
CC
= 4.5V
50
25
75
0
TEMPERATURE (°C)
100
125
0.80
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
4064 G07
4064 G08
4064 G09
sn4064 4064fs
LTC4064
TYPICAL PERFOR A CE CHARACTERISTICS
PROG Pin Voltage
vs Charge Current
1.6
1.4
1.2
V
CC
= 5V
T
A
= 25°C
R
PROG
= 3k
V
PROG
(V)
V
PROG
(V)
V
PROG
(V)
1.0
0.8
0.6
0.4
0.2
0
0
50 100 150 200 250 300 350 400 450 500
CHARGE CURRENT (mA)
4064 G10
Trickle Charge Current
vs Temperature
12
I
BAT
(% OF PROGRAMMED CURRENT)
11
V
BAT
= 2V
T
A
= 25°C
R
PROG
= 3k
I
CHRG
(µA)
30
29
28
V
CHRG
(V)
10
9
8
7
–50 –25
50
25
0
75
TEMPERATURE (°C)
Timer Error vs Temperature
5
4
3
2
V
CC
= 5V
C
TIMER
= 0.1µF
t
TIMER
(%)
0
–1
–2
–3
–4
–5
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
t
TIMER
(%)
1
U W
100
4064 G13
PROG Pin Voltage vs V
CC
Constant Current Mode
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.515
V
BAT
= 3.5V
T
A
= 25°C
R
PROG
= 3k
1.510
1.505
1.500
1.495
1.490
PROG Pin Voltage vs Temperature
Constant Current Mode
V
CC
= 5V
V
BAT
= 4V
R
PROG
= 3k
4
4.5
5
5.5
V
CC
(V)
6
6.5
7
4064 G11
1.485
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
4064 G12
CHRG Pin Weak Pull-Down
Current vs Temperature
35
V
CC
= 5V
34 I
BAT
< C/10
33
32
31
CHRG Pin Output Low Voltage
vs Temperature
0.6
0.5
0.4
0.3
0.2
0.1
0
–50 –25
V
CC
= 5V
I
CHRG
= 5mA
27
26
125
25
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
50
25
75
0
TEMPERATURE (°C)
100
125
4064 G14
4064 G15
Timer Error vs V
CC
5
4
3
2
1
0
–1
–2
–3
–4
–5
4
4.5
5
5.5
V
CC
(V)
6
6.5
7
4064 G17
T
A
= 25°C
C
TIMER
= 0.1µF
4064 G16
sn4064 4064fs
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