LTC1760
Dual Smart Battery
System Manager
DESCRIPTIO
The LTC
®
1760 Smart Battery System Manager is a highly
integrated level 3 battery charger and selector intended for
products using dual smart batteries. Three SMBus inter-
faces allow the LTC1760 to servo to the internal voltage
and currents measured by the batteries while allowing an
SMBus Host to monitor either battery’s status. Charging
accuracy is determined by the battery’s internal voltage
and current measurement, typically better than
±0.2%.
A proprietary PowerPath
TM
architecture supports simulta-
neous 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 genera-
tion of composite battery information. An internal multi-
plexer cleanly switches the SMBus Host to either of the
two attached Smart Batteries without generating partial
messages to batteries or SMBus Host. Thermistors on
both batteries are automatically monitored for tempera-
ture and disconnection information (SafetySignal).
, LTC and LT are registered trademarks of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation.
Protected by U.S. Patents, including *5723970 **6650174
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
■
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 Power Path 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
APPLICATIO S
■
■
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Portable Computers and Instruments
Standalone Dual Smart Battery Chargers
Battery Backup Systems
TYPICAL APPLICATIO
DC
IN
Dual Battery Charger/Selector System Architecture
Dual vs Sequential Charging
SYSTEM
POWER
LTC1760
SMBus (HOST)
SafetySignal 1
SMBus 1
3500
3000
2500
2000
1500
1000
500
0
3500
3000
2500
2000
1500
1000
500
0
0
BATTERY CURRENT (mA)
BAT1
CURRENT
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
U
U
U
BAT1
CURRENT
BAT2
CURRENT
SEQUENTIAL
BAT2
CURRENT
DUAL
100
MINUTES
50
100
150
200
TIME (MINUTES)
250
300
1760f
1
LTC1760
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
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
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
Voltage from DCIN, SCP, SCN, CLP,
V
PLUS
, SW to GND ................................... 32V/–0.3 V
Voltage from SCH1, SCH2 to GND ................ 28V/–0.3 V
Voltage from BOOST to GND ........................ 37V/ –0.3V
CSP, CSN, BAT1, BAT2 to GND ..................... 28V/–0.3V
LOPWR, DCDIV to GND ................................ 10V/ –0.3V
Voltage from V
CC2
, V
DDS
to GND .................... 7V/–0.3 V
SDA1, SDA2, SDA, SCL1, SCL2, SCL, SMBALERT
to GND ........................................................ 7V/–0.3V
MODE to GND ..................................... V
CC2
+0.3V/–0.3V
COMP1 to GND ............................................... 5V/ –0.3V
Maximum DC Current Into Pin
SDA1, SDA2, SDA, SCL1, SCL2, SCL ..............
±3mA
TH1A, TH2A ..................................................... –5mA
TH1B, TH2B .................................................. –102µA
Operating Ambient Temperature (Note 6) .... 0°C to 70°C
Operating Junction Temperature ...........–40°C to 125°C
Storage Temperature .............................–65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1760CFW
T
JMAX
= 125°C,
θ
JA
= 110°C/W
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
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V, V
VCC2
= 5.2V
unless otherwise noted.
SYMBOL
PARAMETER
DCIN Operating Range
I
CH0
I
CH1
I
VCC2_AC1
I
VCC2_AC0
DCIN Operating Current
V
CC2
Operating Current
CONDITIONS
DCIN Selected
Not Charging (DCIN Selected) (Note 10)
Charging (DCIN Selected) (Note 10)
AC Present (Note 11)
AC Not Present (Note 11)
6
0
175
0.8
0.7
0.7
0.7
●
●
I
VCC
= 0mA to 10mA
With Respect to Voltage Reported by Battery
V
CHMIN
< Requested Voltage < V
LIMIT
●
●
–32
3
4.9
5.2
0.2
5
5.5
1
32
MIN
6
1
1.3
0.75
75
TYP
MAX
28
1.5
2
1
100
28
28
UNITS
V
mA
mA
mA
µA
V
V
µA
V
V
V
V
V
V
%
mV
1760f
ELECTRICAL CHARACTERISTICS
Supply and Reference
Battery Operating Voltage Range Battery Selected, PowerPath Function
Battery Selected, Charging Function (Note 2)
I
BAT
V
FDC
V
FB1
V
FB2
V
FSCN
UVLO
V
VCC
V
LDR
V
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
V
CC
Regulator Output Voltage
V
CC
Load Regulation
Voltage Accuracy
Battery Selected, Not Charging, V
DCIN
= 0V (Note 10)
I
VCC
= 10mA
I
VCC
= 0mA
I
VCC
= 0mA
I
VCC
= 0mA
Undervoltage Lockout Threshold V
PLUS
Ramping Down, Measured at V
PLUS
to GND
Switching Regulator
2
U
W
U
U
W W
W
LTC1760
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V, V
VCC2
= 5.2V
unless otherwise noted.
SYMBOL
I
TOL
PARAMETER
Current Accuracy
CONDITIONS
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%
MIN
TYP
MAX
UNITS
ELECTRICAL CHARACTERISTICS
●
●
●
●
–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/I
1
Input Common Mode Low
CA1/I
1
Input Common Mode High
CL1 Turn-On Threshold
●
V
ITH
= 2.2V
V
CSP
= V
CSN
> 5V
140
190
mV
µA
V
V
DCIN
– 0.2
95
94
100
100
50
50
50
40
●
V
mV
mV
ns
ns
ns
ns
V
mV
nA
mV
V
%
105
108
90
90
90
80
1.215
200
115
7.9
TG t
r
TG t
f
BG t
r
BG t
f
Trip Points
V
TR
V
THYS
I
BVT
V
TSC
V
FTO
V
OVSD
DACs
I
RES
t
IP
t
ILOW
TGATE Transition Time:
TGATE Rise Time
TGATE Fall Time
BGATE Transition Time:
BGATE Rise Time
BGATE Fall Time
DCDIV/LOPWR Threshold
DCDIV/LOPWR Hysteresis Voltage
DCDIV/LOPWR Input Bias Current
Short-Circuit Comparator Threshold
Fast Power Path Turn-Off Threshold
Overvoltage Shutdown Threshold as a
Percent of Programmed Charger Voltage
I
DAC
Resolution
I
DAC
Pulse Period:
Normal Mode
Wake-Up Mode
Charging Current Granularity
C
LOAD
= 3300pF, 10% to 90%
C
LOAD
= 3300pF, 10% to 90%
C
LOAD
= 3300pF, 10% to 90%
C
LOAD
= 3300pF, 10% to 90%
V
DCDIV
or V
LOPWR
Falling
V
DCDIV
or V
LOPWR
Rising
V
DCDIV
or V
LOPWR
= 1.19V
V
SCP
– V
SCN
, V
CC
≥
5V
V
DCDIV
Rising from V
CC
V
SET
Rising from 0.8V until TGATE and BGATE
Stop Switching
Guaranteed Monotonic
10
6
R
ILIMIT
= (Short I
LIMIT
to GND)
R
ILIMIT
= 10k
±1%
R
ILIMIT
= 33k
±1%
R
ILIMIT
= Open (or Short I
LIMIT
to V
CC2
)
60
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
)
Guaranteed Monotonic (5V < V
BAT
< 25V)
●
●
●
●
●
1.166
1.19
30
20
90
6
100
7
107
Bits
10
50
1
2
4
4
80
1000
2000
3000
4000
100
1070
2140
3210
4280
15
µs
ms
mA
mA
mA
mA
mA
mA
mA
mA
mA
Bits
1760f
I
WAKE_UP
I
LIMIT
Wake-Up Charging Current (Note 5)
Charging Current Limit
980
1960
2490
3920
11
V
RES
V
DAC
Resolution
3
LTC1760
ELECTRICAL CHARACTERISTICS
SYMBOL
V
STEP
V
LIMIT
PARAMETER
V
DAC
Granularity
Charging Voltage Limit
(Note 7)
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V, V
VCC2
= 5.2V
unless otherwise noted.
CONDITIONS
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
I
LOAD
=10µA
V
GCH1
– V
SCH1
V
GCH2
– V
SCH2
V
BATX
– V
CSN
, 5V
≤
V
BATX
≤
28V
V
CSN
– V
BATX
, 5V
≤
V
BATX
≤
28V
V
GCHX
– V
SCHX
= 1.5V
–2
2
3.5
4.7
µA
µA
V
●
●
●
●
●
●
●
MIN
8400
12608
16832
21024
TYP
16
8432
12640
16864
21056
32768
5
15
MAX
8464
12672
16896
21088
UNITS
mV
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
CH Gate Off Voltage
GCH1
GCH2
CH Switch Reverse Turn-Off Voltage
CH Switch Forward Regulation Voltage
GCH1/GCH2 Active Regulation:
Max Source Current
Max Sink Current
BATX Voltage Below Which
Charging is Inhibited (Does Not Apply
to Wake-Up Mode)
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 Switch Forward
Regulation Voltage
GDCI/GB1I/GB2I Active Regulation:
Source Current
Sink Current
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
V
BATX
– V
SCP
or V
DCIN
– V
SCP
6V
≤
V
SCP
≤
28V
(Note 3)
–4
75
µA
µA
1760f
10
5
5
–0.8
–0.8
5
15
5.8
5.8
–0.4
–0.4
20
35
7
7
0
0
40
60
V
V
V
V
mV
mV
V
COFF
V
TOC
V
FC
I
OC(SRC)
I
OC(SNK)
V
CHMIN
PowerPath Switches
t
DLY
t
PPB
t
ONPO
t
OFFPO
V
PONO
250
1
●
●
ms
sec
10
7
µs
µs
5
3
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
60
50
V
V
V
V
V
V
mV
mV
V
POFFO
V
TOP
V
FP
●
●
5
0
20
25
I
OP(SRC)
I
OP(SNK)
4
LTC1760
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, V
VDDS
= 3.3V, V
VCC2
= 5.2V
unless otherwise noted.
SYMBOL
t
ONPI
t
OFFPI
V
PONI
PARAMETER
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
Thermistor Trip
(COLD-RANGE/OVER-RANGE)
Thermistor Trip
(IDEAL-RANGE/COLD-RANGE)
Thermistor Trip
(HOT-RANGE/IDEAL-RANGE)
Thermistor Trip
(UNDER-RANGE/HOT-RANGE)
Logic Levels
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Low Voltage (V
IL
)
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input High Voltage (V
IH
)
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Leakage Current
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Leakage Current
I
PULLUP
SCL1/SDA1/SCL2/SDA2 Pull-Up
Current When Not Connected to
SMBus Host
SCL1/SDA1/SCL2/SDA2
Series Impedance to Host SMBus
SCL/SDA Output Low Voltage (V
OL
).
LTC1760 Driving the Pin
SCL1/SDA1/SCL2/SDA2 Pullup
Output Low Voltage (VOL).
LTC1760 Driving the Pin with Battery
SMBus not Connected to Host SMBus
SCL1/SDA1/SCL2/SDA2
Output Low Voltage (V
OL
).
LTC1760 Driving the Pin with Battery
SMBus Connected to Host SMBus
V
SDA
, V
SCL
, V
SDA1
, V
SCL1
,
V
SDA2
, V
SCL2
= 0.8V
V
SDA
, V
SCL
, V
SDA1
, V
SCL1
, V
SDA2
,
V
SCL2
= 2.1V
V
SCL1
= V
SDA1
= V
SCL2
= V
SDA2
= 0.4V
V
VCC2
= 4.85V and 5.55V (Current is Through
Internal Series Resistor and Schottky to V
CC2
)
V
SDA1
, V
SCL1
, V
SDA2
, V
SCL2
= 0.8V
I
PULLUP
= 350µA
I
PULLUP
Internal to LTC1760
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
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
C
LOAD(MAX)
= 300pF (Note 9)
R1A = R2A = 1130Ω
±1%
R1B = R2B = 54900Ω
±1%
C
LOAD(MAX)
= 300pF (Note 9)
R1A = R2A = 1130Ω
±1%
R1B = R2B = 54900Ω
±1%
C
LOAD(MAX)
= 300pF (Note 9)
R1A = R2A = 1130Ω
±1%
R1B = R2B = 54900Ω
±1%
C
LOAD(MAX)
= 300pF (Note 9)
R1A = R2A = 1130Ω
±1%
R1B = R2B = 54900Ω
±1%
●
MIN
TYP
300
10
MAX
UNITS
µs
µs
4.75
4.75
4.75
6.7
6.7
6.7
0.18
0.18
0.18
7.5
7.5
7.5
0.25
0.25
0.25
105
V
V
V
V
V
V
kΩ
V
POFFI
Thermistor
95
100
●
28.5
30
32.5
kΩ
●
2.85
3
3.15
kΩ
●
425
500
575
Ω
0.8
2.1
–5
–5
165
220
5
5
350
V
V
µA
µA
µA
300
0.4
0.4
Ω
V
V
I
PULLUP
= 350µA on Host Side
●
0.4
V
1760f
5
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