FEATURES
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LTC1760
Dual Smart Battery
System Manager
DESCRIPTION
The LTC
®
1760 Smart Battery System Manager is a highly-
integrated SMBus Level 3 battery charger and selector
intended for products using dual smart batteries. Three
SMBus interfaces allow the LTC1760 to servo to the
internal voltage and currents measured by the batteries
while allowing an SMBus Host device to monitor either
battery’s status. Charging accuracy is determined by the
battery’s internal voltage and current measurements, typi-
cally better than ±0.2%.
A proprietary PowerPath architecture supports simultane-
ous charging or discharging of both batteries. Typical battery
run times are extended by up to 10%, while charging times
are reduced by up to 50%. The LTC1760 automatically
switches between power sources in less than 10μs to prevent
power interruption upon battery or wall adapter removal.
The LTC1760 implements all elements of a version 1.1
“Smart Battery System Manager” except for the generation
of composite battery information. An internal multiplexer
cleanly switches the SMBus Host to either of the two
attached Smart Batteries without generating partial mes-
sages to batteries or SMBus Host. Thermistors on both
batteries are automatically monitored for temperature and
disconnection information (SafetySignal).
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including *5723970 **6650174.
SMBus Charger/Selector for Two Smart Batteries*
Voltage and Current Accuracy within 0.2% of Value
Reported by Battery
Simplifies Construction of “Smart Battery System
Manager”
Includes All SMBus Charger V1.1 Safety Features
Supports Autonomous Operation without a Host
Allows Both Batteries to Discharge Simultaneously
into Single Load with Low Loss (Ideal Diode)
SMBus Switching for Dual Batteries with Alarm
Monitoring for Charging Battery at All Times
Pin Programmable Limits for Maximum Charge
Current and Voltage Improve Safety
Fast Autonomous PowerPath
™
Switching (<10μs)
Low Loss Simultaneous Charging of Two Batteries
>95% Efficient Synchronous Buck Charger
AC Adapter Current Limiting* Maximizes Charge Rate
SMBus Accelerator Improves SMBus Timing**
Available in 48-Lead TSSOP Package
APPLICATIONS
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Portable Computers and Instruments
Standalone Dual Smart Battery Chargers
Battery Backup Systems
TYPICAL APPLICATION
Dual Battery Charger/Selector System Architecture
DC
IN
BATTERY CURRENT (mA)
Dual vs Sequential Charging
3500
3000
2500
2000
1500
1000
500
0
3500
3000
2500
2000
1500
1000
500
0
0
BAT1
CURRENT
BAT2
CURRENT
SEQUENTIAL
SYSTEM
POWER
LTC1760
SMBus (HOST)
BAT1
CURRENT
BAT2
CURRENT
DUAL
100
MINUTES
SafetySignal 1
SMBus 1
50
100
150
200
TIME (MINUTES)
250
300
SafetySignal 2
SMBus 2
1760 TA01
BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020)
REQUESTED CURRENT = 3A
REQUESTED VOLTAGE = 12.3V
MAX CHARGER CURRENT = 4.1A
1760 TA03
1760fa
1
LTC1760
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
V
PLUS
BAT2
BAT1
SCN
SCP
GDCO
GDCI
GB1O
GB1I
GB2O
GB2I
LOPWR
V
SET
I
TH
I
SET
DCDIV
SCL2
SCL
SCL1
V
DDS
SDA2
SDA
SDA1
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
FW PACKAGE
48-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
SCH2
GCH2
GCH1
SCH1
TGATE
BOOST
SW
DCIN
V
CC
BGATE
PGND
COMP1
CLP
CSP
CSN
V
LIMIT
I
LIMIT
TH1B
TH1A
SMBALERT
TH2A
TH2B
MODE
V
CC2
DCIN, SCP, SCN, CLP,
V
PLUS
, SW to GND ..................................... –0.3V to 32V
SCH1, SCH2 to GND ................................... –0.3V to 28V
BOOST to GND ........................................... –0.3V to 37V
CSP, CSN, BAT1, BAT2 to GND ................... –0.3V to 28V
LOPWR, DCDIV to GND ............................. –0.3V to 10V
V
CC2
, V
DDS
to GND ....................................... –0.3V to 7V
SDA1, SDA2, SDA, SCL1,
SCL2, SCL,
SMBALERT
to GND.................... –0.3V to 7V
MODE to GND .................................–0.3V to V
CC2
+0.3V
COMP1 to GND ............................................ –0.3V to 5V
Maximum DC Current Into Pin
SDA1, SDA2, SDA, SCL1, SCL2, SCL ................ ±3mA
TH1A, TH2A ..................................................... –5mA
TH1B, TH2B ................................................... –102μA
Operating Junction Temperature Range
(Note 6).................................................. –40°C to 125°C
Storage Temperature.............................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
ORDER INFORMATION
LEAD FREE FINISH
LTC1760CFW#PBF
LTC1760IFW#PBF
TAPE AND REEL
LTC1760CFW#TRPBF
LTC1760IFW#TRPBF
PART MARKING
LTC1760CFW
LTC1760IFW
PACKAGE DESCRIPTION
48-Lead Plastic TSSOP
48-Lead Plastic TSSOP
TEMPERATURE RANGE
0°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
1760fa
2
LTC1760
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 6). V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V,
V
VCC2
= 5.2V unless otherwise noted.
SYMBOL PARAMETER
Supply and Reference
DCIN Operating Range
I
CH0
I
CH1
DCIN Operating Current
DCIN Selected
Not Charging (DCIN Selected) (Note 10)
Charging (DCIN Selected) (Note 10)
AC Present (Note 11)
AC Not Present (Note 11)
Battery Selected, PowerPath Function
Battery Selected, Charging Function (Note 2)
Battery Selected, Not Charging, V
DCIN
= 0V (Note 10)
I
VCC
= 10mA
I
VCC
= 0mA
I
VCC
= 0mA
I
VCC
= 0mA
V
PLUS
Ramping Down, Measured at V
PLUS
to GND
I
VCC
= 0mA to 10mA
With Respect to Voltage Reported by Battery
V
CHMIN
< Requested Voltage < V
LIMIT
With Respect to Current Reported by Battery
4mV/R
SENSE
< Requested Current < I
LIMIT
(Min)
(Note 12)
R
ILIMIT
= 0 (Short to GND)
R
ILIMIT
= 10k ±1%
R
ILIMIT
= 33k ±1%
R
ILIMIT
= Open (or Short I
LIMIT
to V
CC2
)
Duty Cycle ≥99%
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
6
TYP
MAX
28
UNITS
V
mA
mA
mA
μA
V
V
μA
V
V
V
V
1
1.3
0.75
75
6
0
175
0.8
0.7
0.7
0.7
3
4.9
5.2
0.2
–32
1.5
2
1
100
28
28
I
VCC2_AC1
V
CC2
Operating Current
I
VCC2_AC0
Battery Operating Voltage Range
I
BAT
V
FDC
V
FB1
V
FB2
V
FSCN
UVLO
V
VCC
V
LDR
V
TOL
I
TOL
Battery Drain Current
V
PLUS
Diodes Forward Voltage:
DCIN to V
PLUS
BAT1 to V
PLUS
BAT2 to V
PLUS
SCN to V
PLUS
Undervoltage Lockout Threshold
V
CC
Regulator Output Voltage
V
CC
Load Regulation
Voltage Accuracy
Current Accuracy
5
5.5
1
32
V
V
%
mV
Switching Regulator
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–2
–4
–8
–8
255
20
99
300
25
99.5
155
150
0
2
4
8
8
345
mA
mA
mA
mA
kHz
kHz
%
f
0SC
f
DO
DC
MAX
I
MAX
I
SNS
CMSL
CMSH
V
CL1
Regulator Switching Frequency
Regulator Switching Frequency in Low
Dropout Mode
Regulator Maximum Duty Cycle
Maximum Current Sense Threshold
CA1 Input Bias Current
CA1 Input Common Mode Low
CA1 Input Common Mode High
CL1 Turn-On Threshold
C-Grade (Note 6)
I-Grade (Note 6)
l
l
V
ITH
= 2.2V
V
CSP
= V
CSN
> 5V
140
190
mV
μA
V
V
DCIN
– 0.2
95
94
90
100
100
100
50
50
50
40
105
108
108
90
90
90
80
V
mV
mV
mV
ns
ns
ns
ns
TG t
r
TG t
r
BG t
r
BG t
f
TGATE Transition Time:
TGATE Rise Time
TGATE Fall Time
BGATE Transition Time
BGATE Rise Time
BGATE Fall Time
,
C
LOAD
= 3300pF 10% to 90%
= 3300pF 10% to 90%
,
C
LOAD
,
C
LOAD
= 3300pF 10% to 90%
,
C
LOAD
= 3300pF 10% to 90%
1760fa
3
LTC1760
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 6). V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V,
V
VCC2
= 5.2V unless otherwise noted.
SYMBOL PARAMETER
Trip Points
V
TR
DCDIV/LOPWR Threshold
V
DCDIV
or V
LOPWR
Falling
C-Grade (Note 6)
I-Grade (Note 6)
V
DCDIV
or V
LOPWR
Rising
V
DCDIV
or V
LOPWR
= 1.19V
V
SCP
– V
SCN
, V
CC
≥ 5V
C-Grade (Note 6)
I-Grade (Note 6)
V
DCDIV
Rising from V
CC
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
TYP
MAX
UNITS
1.166
1.162
1.19
1.19
30
20
1.215
1.215
200
115
115
7.9
V
V
mV
nA
mV
mV
V
%
V
THYS
I
BVT
V
TSC
DCDIV/LOPWR Hysteresis Voltage
DCDIV/LOPWR Input Bias Current
Short-Circuit Comparator Threshold
90
88
6
100
100
7
107
V
FTO
V
OVSD
DACs
I
RES
t
IP
t
ILOW
Fast PowerPath Turn-Off Threshold
Overvoltage Shutdown Threshold as a
V
SET
Rising from 0.8V until TGATE and BGATE
Percent of Programmed Charger Voltage Stop Switching
I
DAC
Resolution
I
DAC
Pulse Period:
Normal Mode
Wake-Up Mode
Charging Current Granularity
R
ILIMIT
= 0 (Short I
LIMIT
to GND)
R
ILIMIT
= 10k ±1%
R
ILIMIT
= 33k ±1%
R
ILIMIT
= Open (or Short I
LIMIT
to V
CC2
)
60
C-Grade (Note 6)
R
ILIMIT
= 0 (Short I
LIMIT
to GND)
R
ILIMIT
= 10k ±1%
R
ILIMIT
= 33k ±1%
R
ILIMIT
= Open (or Short I
LIMIT
to V
CC2
)
I-Grade (Note 6)
R
ILIMIT
= 0 (Short I
LIMIT
to GND)
R
ILIMIT
= 10k ±1%
R
ILIMIT
= 33k ±1%
R
ILIMIT
= Open (or Short I
LIMIT
to V
CC2
)
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Guaranteed Monotonic
10
6
10
50
1
2
4
4
80
1000
2000
3000
4000
100
1070
2140
3210
4280
15
Bits
μs
ms
mA
mA
mA
mA
mA
mA
mA
mA
mA
I
WAKE_UP
Wake-Up Charging Current (Note 5)
I
LIMIT
Charging Current Limit
980
1960
2490
3920
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930
1870
2380
3750
11
1000
2000
3000
4000
16
1110
2220
3320
4430
mA
mA
mA
mA
Bits
mV
V
RES
V
STEP
V
LIMIT
V
DAC
Resolution
V
DAC
Granularity
Charging Voltage Limit
(Note 7)
Guaranteed Monotonic (5V < V
BAT
< 25V)
R
VLIMIT
= 0 (Short V
LIMIT
to GND)
R
VLIMIT
= 10k ±1%
R
VLIMIT
= 33k ±1%
R
VLIMIT
= 100k ±1%
R
VLIMIT
= Open (or Short V
LIMIT
to V
CC2
)(Note 13)
V
GCHX
– V
SCHX
> 3V, C
LOAD
= 3000pF
V
GCHX
– V
SCHX
< 1V, from Time of
V
CSN
< V
BATX
– 30mV, C
LOAD
= 3000pF
I
LOAD
= 1μA
V
GCH1
– V
SCH1
V
GCH2
– V
SCH2
l
l
l
l
l
8400
12608
16832
21024
8432
12640
16864
21056
32768
5
15
8464
12672
16896
21088
mV
mV
mV
mV
mV
ms
μs
Charge MUX Switches
t
ONC
t
OFFC
V
CON
GCH1/GCH2 Turn-On Time
GCH1/GCH2 Turn-Off Time
CH Gate Clamp Voltage
GCH1
GCH2
10
5
5
5.8
5.8
7
7
V
V
1760fa
4
LTC1760
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 6). V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V,
V
VCC2
= 5.2V unless otherwise noted.
SYMBOL PARAMETER
V
COFF
CH Gate Off Voltage
GCH1
GCH2
CH Switch Reverse Turn-Off Voltage
CONDITIONS
I
LOAD
=10μA
V
GCH1
– V
SCH1
V
GCH2
– V
SCH2
V
BATX
– V
CSN
, 5V ≤ V
BATX
≤ 28V
C-Grade (Note 6)
I-Grade (Note 6)
V
CSN
– V
BATX
, 5V ≤ V
BATX
≤ 28V
V
GCHX
– V
SCHX
= 1.5V
–2
2
(Note 14)
3.5
4.7
μA
μA
V
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ELECTRICAL CHARACTERISTICS
MIN
–0.8
–0.8
5
2
15
TYP
–0.4
–0.4
20
20
35
MAX
0
0
40
40
60
UNITS
V
V
mV
mV
mV
V
TOC
V
FC
I
OC(SRC)
I
OC(SNK)
V
CHMIN
CH Switch Forward Regulation Voltage
GCH1/GCH2 Active Regulation:
Max Source Current
Max Sink Current
BATX Voltage Below Which
Charging is Inhibited
Blanking Period after UVLO Trip
Blanking Period after LOPWR Trip
GB1O/GB2O/GDCO Turn-On Time
GB1O/GB2O/GDCO Turn-Off Time
Output Gate Clamp Voltage
GB1O
GB2O
GDCO
Output Gate Off Voltage
GB1O
GB2O
GDCO
PowerPath Switch Reverse
Turn-Off Voltage
PowerPath Switches
t
DLY
t
PPB
t
ONPO
t
OFFPO
V
PONO
Switches Held Off
Switches in 3-Diode Mode
V
GS
< –3V, from Time of Battery/DC
Removal, or LOPWR Indication, C
LOAD
= 3000pF
V
GS
> –1V, from Time of Battery/DC
Removal, or LOPWR Indication, C
LOAD
= 3000pF
I
LOAD
= 1μA
Highest (V
BAT1
or V
SCP
) – V
GB1O
Highest (V
BAT2
or V
SCP
) – V
GB2O
Highest (V
DCIN
or V
SCP
) – V
GDCO
I
LOAD
= –25μA
Highest (V
BAT1
or V
SCP
) – V
GB1O
Highest (V
BAT2
or V
SCP
) – V
GB2O
Highest (V
DCIN
or V
SCP
) – V
GDCO
V
SCP
– V
BATX
or V
SCP
– V
DCIN
6V ≤ V
SCP
≤ 28V
C-Grade (Note 6)
I-Grade (Note 6)
V
BATX
– V
SCP
or V
DCIN
– V
SCP
6V ≤ V
SCP
≤ 28V
(Note 3)
–4
75
V
GS
< –3V, C
LOAD
= 3000pF (Note 4)
V
GS
> –1V, C
LOAD
= 3000pF (Note 4)
I
LOAD
= 1μA
Highest (V
BAT1
or V
SCP
) – V
GB1I
Highest (V
BAT2
or V
SCP
) – V
GB2I
Highest (V
DCIN
or V
SCP
) – V
GDCI
I
LOAD
= –25μA
Highest (V
BAT1
or V
SCP
) – V
GB1I
Highest (V
BAT2
or V
SCP
) – V
GB2I
Highest (V
DCIN
or V
SCP
) – V
GDCI
4.75
4.75
4.75
300
10
6.7
6.7
6.7
0.18
0.18
0.18
7.5
7.5
7.5
0.25
0.25
0.25
μA
μA
μs
μs
V
V
V
V
V
V
l
l
250
1
5
3
10
7
ms
sec
μs
μs
4.75
4.75
4.75
6.25
6.25
6.25
0.18
0.18
0.18
7
7
7
0.25
0.25
0.25
V
V
V
V
V
V
V
POFFO
V
TOP
l
l
l
5
2
0
20
20
25
60
60
50
mV
mV
mV
V
FP
PowerPath Switch Forward
Regulation Voltage
GDCI/GB1I/GB2I Active Regulation:
Source Current
Sink Current
Gate B1I/B2I/DCI Turn-On Time
Gate B1I/B2I/DCI Turn-Off Time
Input Gate Clamp Voltage
GB1I
GB2I
GDCI
Input Gate Off Voltage
GB1I
GB2I
GDCI
I
OP(SRC)
I
OP(SNK)
t
ONPI
t
OFFPI
V
PONI
V
POFFI
1760fa
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