LTC3305
Lead-Acid Battery Balancer
FEATURES
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DESCRIPTION
The
LTC
®
3305
balances up to 4 lead-acid batteries
connected in series. It is intended to be used in conjunction
with a separate pre-existing battery charger as part of a
high performance battery system. All voltage monitoring,
gate drive, and fault detection circuitry is integrated.
The LTC3305 employs an auxiliary battery or an alternative
storage cell to transfer charge to or from each individual
battery in the stack. A mode pin provides two operating
modes, timer mode and continuous mode. In timer mode,
once the balancing operation is completed, the LTC3305
goes into a low power state for a programmed time and then
periodically rebalances the batteries. In continuous mode,
the balancing operation continues even after the batteries
are balanced to their programmed termination voltage.
The LTC3305 is available in a thermally enhanced 38-lead
TSSOP package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
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Single IC Balances Up to Four 12V Lead-Acid
Batteries in Series
All NFET Design
Stackable to Balance Larger Series Battery Packs
Standalone Balancing Operation: Requires No
External μP or Additional Control Circuitry
Balancing Current Limited by External PTC Thermistor
Continuous Mode and Timer Mode
Programmable UV and OV Fault Thresholds
Programmable Termination Time and Termination
Voltage
Thermally Enhanced 38-Lead TSSOP Package
APPLICATIONS
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Telecom Backup Systems
Home Battery Powered Backup Systems
Industrial Electric Vehicles
Energy Storage Systems (ESS)
Medical Equipment
TYPICAL APPLICATION
4-Battery Balancer with Programmed High and Low Battery Voltage Faults
10µF
25V
CHARGER
SUPPLY
I
CHARGE
BATTERY
STACK
CHARGER
1µF
6V
V
REG
CM
EN1
EN2
MODE
TERM1
TERM2
UVFLT
OVFLT
DONE
BAL
PTCFLT
BATX
BATY
CTON
CTOFF
CTBAT
V
L
27.4k
V
H
42.2k
I
SET
12.1k
GND
CP
249
BOOST
V4
10µF
25V
10µF
25V
V3
10µF
25V
1.33k
NGATE5
6.04k
Battery Voltages Converge
Over Time
16
14
NGATE4
6.04k
+
BAT4
100k EACH
NGATE3
3.01k
+
BATTERY VOLTAGE (V)
BAT3
12
10
8
6
4
2
0
TIME
3305 TA01a
10nF
100nF
LTC3305
V2
10µF
25V
V1
10µF
25V
9
NGATE7
PTC
AUXP
AUXN
10µF
25V
+
AUX
6.04k
NGATE8
3305 TA01
NGATE2
6.04k
+
BAT2
NGATE6
6.04k
10nF
NGATE1
6.04k
+
BAT1
NGATE1-9
BATTERY 1
BATTERY 2
BATTERY 3
BATTERY 4
6.04k
6.04k
NGATE9
3305fb
For more information
www.linear.com/LTC3305
1
LTC3305
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
BOOST
V4
V3
AUXP
AUXN
V2
V1
NGATE1
NGATE2
1
2
3
4
5
6
7
8
9
39
GND
38 CM
37 CP
36 NC
35 MODE
34 EN1
33 EN2
32 TERM1
31 TERM2
30 V
REG
29 I
SET
28 V
H
27 V
L
26 CTBAT
25 CTON
24 CTOFF
23
PTCFLT
22
DONE
21
BAL
20
UVFLT
Stack Voltage, V4 to GND .........................................68V
Battery Voltages, V4 to V3, V3 to V2, V2 to V1,
V1 to GND .................................................. –0.3V to 20V
Auxiliary Cell Voltage, AUXP to AUXN........ –0.3V to 20V
V
REG
Voltage ................................................ –0.3V to 6V
V
H
, V
L
Voltage..... –0.3V to Lesser of 6V or (V
REG
+0.3V)
UVFLT, OVFLT, PTCFLT, BAL, DONE,
BATX,
BATY Voltage ............................................... –0.3V to 6V
EN1, EN2, MODE, TERM1, TERM2
Voltage ................ –0.3V to Lesser of 6V or (V
REG
+0.3V)
NGATE1, NGATE2, NGATE3, NGATE4, NGATE8, NGATE9
Voltage.............. –0.3V to Lesser of 68V or (V4+0.3V)
NGATE5, NGATE6, NGATE7
Voltage.............. (Greater of –0.3V or BOOST–68V) to
(BOOST+0.3V)*
UVFLT, OVFLT, PTCFLT, BAL, DONE,
BATX,
BATY Current .........................................................10mA
I
SET
Current..............................................................1mA
CP, CM Current.......................................................50mA
Operating Junction Temperature Range
(Notes 2, 3) ............................................ –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
*The BOOST voltage is generated by the LTC3305 and is typically 8.45V higher than V4.
NGATE3 10
NGATE4 11
NGATE5 12
NGATE6 13
NGATE7 14
NGATE8 15
NGATE9 16
BATX 17
BATY 18
OVFLT
19
FE PACKAGE
38-LEAD PLASTIC TSSOP
θ
JA
= 28°C/W
EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB
NC = No Connect
(http://www.linear.com/product/LTC3305#orderinfo)
LEAD FREE FINISH
LTC3305EFE#PBF
LTC3305IFE#PBF
TAPE AND REEL
LTC3305EFE#TRPBF
LTC3305IFE#TRPBF
PART MARKING*
LTC3305 FE
LTC3305 FE
PACKAGE DESCRIPTION
38-Lead Plastic TSSOP
38-Lead Plastic TSSOP
TEMPERATURE RANGE
–40ºC to 125°C
–40ºC to 125°C
ORDER INFORMATION
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
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3305fb
For more information
www.linear.com/LTC3305
LTC3305
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. (Note 2) V1 = 13.2V, V2 = 26.4V, V3 = 39.6V, V4 = 52.8V,
AUXP - AUXN = 13.2V, R
ISET
= 12.1kΩ
SYMBOL
V
BAT
V4
V
REG
V
REG,UV
PARAMETER
Individual Battery Voltage
Voltage at the Top of the Battery Stack
Regulator Output Voltage
Regulator Undervoltage Threshold
Hysteresis
Maximum Guaranteed Load Current
Regulator Short Circuit Current Limit
Shutdown Current
Supply Current While Balancing Battery 1
(Notes 4, 5)
V
REG
> V
REG,UV
V
REG
= 0V
Measured at V4, BOOST-V4 = 0V
Measured at V3, V2, V1, AUXP, BOOST
Measured at V4
Measured at V3
Measured at V2
Measured at V1
Measured at V4
Measured at V3
Measured at V2
Measured at V1
Measured at V4
Measured at V3
Measured at V2
Measured at V1
Measured at V4
Measured at V3
Measured at V2
Measured at V1
Measured at AUXP
Measured at AUXN
Measured at V4, BOOST-V4 = 0V
Measured at V3, V2, V1, AUXP, BOOST
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ELECTRICAL CHARACTERISTICS
CONDITIONS
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MIN
4
12
2.4
1.7
3
8
16
TYP
MAX
16
64
UNITS
V
V
V
V
mV
mA
I
VREG
= 200µA
Regulator Voltage Falling
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2.5
2.1
125
15
33
0
900
0
0
150
900
0
150
–45
900
150
–45
0
1050
–45
0
0
165
–130
100
0
220
2.6
22
50
1
1350
1
1
225
1350
1
225
1350
225
1
1575
1
1
245
150
1
330
1.22
35.3
2.4
1.2
2
3
1.5
mA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
µA
V
µA
mA
mA
µA
mA
mA
V
V
mV
V
V
V
mV
V
Supply Current While Balancing Battery 2
(Notes 4, 5)
–70
Supply Current While Balancing Battery 3
(Notes 4, 5)
–70
Supply Current While Balancing Battery 4
(Notes 4, 5)
–70
Supply Current While Balancing any Battery
Supply Current in OFF State (MODE = 0)
Boost Pin Current While Balancing any Battery
(Notes 4, 5)
V
ISET
I
VH,
I
VL
I
NGATE
I
SET
Servo Voltage
Current Out of V
H
and V
L
Pins
Current For External NMOS Turn On (Note 5)
Leakage Current in Shutdown
Current Programmable Range
V
BAT,UV
–195
50µA< I
ISET
< 150µA
I
ISET
= 100µA
NGATE3 Current, I
ISET
= 100µA
All Other NGATE Currents, I
ISET
= 100µA
EN1 = EN2 = 0
NGATE3 Current
All Other NGATE Currents
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1.18
31.3
2.0
1.0
–2
1
0.5
3.9
15.6
4
3.9
15.6
4
1.2
33.3
2.2
1.1
Undervoltage Falling Battery Threshold (Note 6) V
L
= 0.4V
V
L
= 1.6V
Undervoltage Hysteresis
Undervoltage Falling Programmable Range
4
16
120
4.1
16.4
16
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V
BAT,OV
Overvoltage Rising Battery Threshold (Note 6)
Overvoltage Hysteresis
Overvoltage Rising Programmable Range
V
H
= 0.4V
V
H
= 1.6V
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4
16
150
4.1
16.4
16
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3305fb
For more information
www.linear.com/LTC3305
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LTC3305
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. (Note 2) V1 = 13.2V, V2 = 26.4V, V3 = 39.6V, V4 = 52.8V,
AUXP - AUXN = 13.2V, R
ISET
= 12.1kΩ
SYMBOL
PARAMETER
PTC Fault Threshold
Hysteresis
V
TERMINATE
|BAT-AUXP| for Which Balancing Is Terminated TERM2 = 0, TERM1 = 0
TERM2 = 0, TERM1 = 1
TERM2 = 1, TERM1 = 0
TERM2 = 1, TERM1 = 1
Minimum (BOOST-V4) Voltage for Operation
Hysteresis
Maximum (BOOST-V4) Voltage Regulated
Hysteresis
R
NMOS
R
PMOS
t
BAT
t
ON
t
OFF
V
IH
V
IL
I
IH,
I
IL
V
OL
I
OH
Charge Pump NMOS Switch ON Resistance
Charge Pump PMOS Switch ON Resistance
Maximum Time a Single Battery Stays
Connected to the Auxiliary Battery
Maximum Stack Balancing Termination Time
Off Time After Stack Balance Termination
Digital Input High Voltage
Digital Input Low Voltage
Leakage Current
Output Low Voltage
Output High Leakage Current
Thermal Shutdown Threshold (Note 7)
Thermal Shutdown Hysteresis
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 LTC3305 is tested under pulsed load conditions such that T
J
≈ T
A
. The LTC3305E is guaranteed to meet specifications from 0ºC to 85ºC
junction temperature. Specifications over the –40ºC to 125ºC operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3305I is guaranteed
over the –40°C to 125°C operating junction temperature range. Note that
the maximum ambient temperature consistent with these specifications
is determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance, and other environmental
factors. The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in Watts) according
to the formula: T
J
= T
A
+ (P
D
• θ
JA
), where
θ
JA
(in °C/W) is the package
thermal impedance.
Measured at 10mA
Measured at 10mA
CTBAT = 10nF
MODE = 0, CTON = 10nF
MODE = 0,
DONE
= 0, CTOFF = 10nF
EN1, EN2, MODE, TERM1, TERM2 Pins
EN1, EN2, MODE, TERM1, TERM2 Pins
EN1, EN2, MODE, TERM1, TERM2 Pins;
2.5V at Pin
BATX, BATY,
BAL, DONE,
UVFLT, OVFLT, PTCFLT
Pins; 3mA Into Pin
BATX, BATY,
BAL, DONE,
UVFLT, OVFLT, PTCFLT
Pins; 6V at Pin
Rising Temperature
155
10
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ELECTRICAL CHARACTERISTICS
CONDITIONS
|BAT-AUXP| Falling
MIN
0.8
5.0
17.5
40
85
6.7
TYP
1
100
12.5
25
50
100
6.95
180
8.45
200
20
55
MAX
1.2
20.0
32.5
60
115
7.2
8.75
UNITS
V
mV
mV
mV
mV
mV
V
mV
V
mV
Ω
Ω
4.5
0.43
0.43
1.2
5
0.48
0.48
5.5
0.53
0.53
0.4
sec
hrs
hrs
V
V
µA
mV
µA
°C
°C
–1
27.5
1
150
1
Note 3.
Continuous operation above the specified maximum operating
junction temperature may result in device degradation or failure.
Note 4.
The NGATE pin currents are not included in this number.
Note 5.
The NGATE5
,
NGATE6, NGATE7 pin currents are drawn from the
BOOST pin. All other NGATE pin currents are drawn from the V4 pin. The
NGATE pin currents add to the currents drawn by V4 and BOOST.
Note 6.
The voltage programmed at the V
H
and V
L
pins are gained up to
set the undervoltage and overvoltage thresholds of each battery.
Note 7:
This IC includes overtemperature protection intended to protect
the device during momentary overload conditions. The maximum junction
temperature may be exceeded when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may result in device degradation or failure.
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3305fb
For more information
www.linear.com/LTC3305
LTC3305
TYPICAL PERFORMANCE CHARACTERISTICS
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
T
A
= 25°C, unless otherwise noted.
V
REG
Line and Load Regulation
2.55
2.50
2.45
2.40
2.35
V
REG
(V)
2.30
2.25
2.20
2.15
2.10
V
REG
vs Temperature
2.5
2.4
2.3
2.2
V
REG,UV
(V)
2.1
2.0
1.9
1.8
I
VREG
= 0.2mA, V4 = 52.8V
I
VREG
= 1mA, V4 = 52.8V
I
VREG
= 3mA, V4 = 12V
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G02
V
REG,UV
vs Temperature
RISING
V
REG
(V)
FALLING
V4 = 12V
1.7
1.6
1.5
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G03
V4 = 52.8V
0
3
6
9
CURRENT (mA)
12
15
3305 G01
2.05
2.00
–55 –35 –15
Shutdown Current vs Temperature
55
50
45
40
I
V4
(µA)
I
V4
(µA)
35
30
25
20
15
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G04
OFF State Current vs Temperature
125
120
115
1.220
1.215
V
ISET
vs Temperature
V4 = 64V
110
105
100
95
90
85
80
75
–55 –35 –15
V4 = 64V
V4 = 52.8V
V4 = 12V
V
ISET
(V)
1.210
1.205
1.200
1.195
1.190
1.185
V4 = 52.8V
V4 = 12V
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G05
1.180
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G06
1.8
1.7
ALL NGATE PIN CURRENTS
1.6
AND NGATE3 CURRENT
2
1.5
V4 = 52.8V, V
NGATE
= 0V
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
50 60 70 80 90 100 110 120 130 140 150
I
ISET
(µA)
3305 G07
I
NGATE
vs I
ISET
1.20
I
NGATE
vs Temperature
UV Threshold vs Temperature
5.25
R
ISET
= 12.1k
5.20
R
VL
= 15k
5.15
BATTERY VOLTAGE (V)
5.10
5.05
5.00
4.95
4.90
4.85
4.80
FALLING
RISING
ALL NGATE PIN CURRENTS
1.18
AND NGATE3 CURRENT
2
1.16
V4 = 52.8V, V
NGATE
= 0V, R
ISET
= 12k
1.14
I
NGATE
(mA)
1.12
1.10
1.08
1.06
1.04
1.02
1.00
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G08
I
NGATE
(mA)
4.75
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
3305 G09
3305fb
For more information
www.linear.com/LTC3305
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