Linear Technology LTC1760 User manual

LTC1760
1
1760fc
For more information www.linear.com/LTC1760
TYPICAL APPLICATION
FEATURES DESCRIPTION
Dual Smart Battery
System Manager
The LT C
®
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,
typically better than ±0.2%.
A proprietary PowerPath architecture supports simultane-
ouschargingordischargingofbothbatteries.Typicalbattery
run times are extended by up to 10%, while charging times
are reduced by up to 50%. The LTC1760 automatically
switchesbetweenpowersourcesinlessthan10µstoprevent
power interruption upon battery or wall adapter removal.
The LTC1760 implements all elements of a version 1.1
“SmartBatterySystemManager”except forthe 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).
Dual vs Sequential Charging
APPLICATIONS
nSMBus Charger/Selector for Two Smart Batteries*
nVoltage and Current Accuracy within 0.2% of Value
Reported by Battery
nSimplifies Construction of “Smart Battery System
Manager”
nIncludes All SMBus Charger V1.1 Safety Features
nSupports Autonomous Operation without a Host
nAllows Both Batteries to Discharge Simultaneously
into Single Load with Low Loss (Ideal Diode)
nSMBus Switching for Dual Batteries with Alarm
Monitoring for Charging Battery at All Times
nPin Programmable Limits for Maximum Charge
Current and Voltage Improve Safety
nFast Autonomous PowerPath™Switching (<10µs)
nLow Loss Simultaneous Charging of Two Batteries
n>95% Efficient Synchronous Buck Charger
nAC Adapter Current Limiting* Maximizes Charge Rate
nSMBus Accelerator Improves SMBus Timing**
nAvailable in 48-Lead TSSOP Package
nPortable Computers and Instruments
nStandalone Dual Smart Battery Chargers
nBattery Backup Systems
LTC1760
DC
IN
SYSTEM
POWER
SMBus (HOST)
1760 TA01
SafetySignal 1
SMBus 1
SafetySignal 2
SMBus 2
TIME (MINUTES)
BATTERY CURRENT (mA)
3500
3000
2500
2000
1500
1000
500
0
3500
3000
2500
2000
1500
1000
500
0
1760 TA03
050 100 150 200 250 300
BAT1
CURRENT
BAT2
CURRENT
SEQUENTIAL
DUAL
BAT1
CURRENT
100
MINUTES
BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020)
REQUESTED CURRENT = 3A
REQUESTED VOLTAGE = 12.3V
MAX CHARGER CURRENT = 4.1A
BAT2
CURRENT
Dual Battery Charger/Selector System Architecture
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Analog Devices, Inc. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including *5723970 **6650174.

LTC1760
2
1760fc
For more information www.linear.com/LTC1760
PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS
DCIN, SCP, SCN, CLP,
VPLUS, 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
VCC2, VDDS 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 VCC2 +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
(Note 1)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
TOP VIEW
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
VCC
BGATE
PGND
COMP1
CLP
CSP
CSN
VLIMIT
ILIMIT
TH1B
TH1A
SMBALERT
TH2A
TH2B
MODE
VCC2
VPLUS
BAT2
BAT1
SCN
SCP
GDCO
GDCI
GB1O
GB1I
GB2O
GB2I
LOPWR
VSET
ITH
ISET
DCDIV
SCL2
SCL
SCL1
VDDS
SDA2
SDA
SDA1
GND
TJMAX = 125°C, qJA = 110°C/W
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC1760CFW#PBF LTC1760CFW#TRPBF LTC1760CFW 48-Lead Plastic TSSOP 0°C to 85°C
LTC1760IFW#PBF LTC1760IFW#TRPBF LTC1760IFW 48-Lead Plastic TSSOP –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/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
(http://www.linear.com/product/LTC1760#orderinfo)

LTC1760
3
1760fc
For more information www.linear.com/LTC1760
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply and Reference
DCIN Operating Range DCIN Selected 6 28 V
ICH0
ICH1
DCIN Operating Current Not Charging (DCIN Selected) (Note 10)
Charging (DCIN Selected) (Note 10)
1
1.3
1.5
2
mA
mA
IVCC2_AC1
IVCC2_AC0
VCC2 Operating Current AC Present (Note 11)
AC Not Present (Note 11)
0.75
75
1
100
mA
µA
Battery Operating Voltage Range Battery Selected, PowerPath Function
Battery Selected, Charging Function (Note 2)
6
0
28
28
V
V
IBAT Battery Drain Current Battery Selected, Not Charging, VDCIN = 0V (Note 10) 175 µA
VFDC
VFB1
VFB2
VFSCN
VPLUS Diodes Forward Voltage:
DCIN to VPLUS
BAT1 to VPLUS
BAT2 to VPLUS
SCN to VPLUS
IVCC = 10mA
IVCC = 0mA
IVCC = 0mA
IVCC = 0mA
0.8
0.7
0.7
0.7
V
V
V
V
UVLO Undervoltage Lockout Threshold VPLUS Ramping Down, Measured at VPLUS to GND l3 5 V
VVCC VCC Regulator Output Voltage l4.9 5.2 5.5 V
VLDR VCC Load Regulation No External Connection Beyond Applications Shown
Herein
0.2 1 %
Switching Regulator
VTOL Voltage Accuracy With Respect to Voltage Reported by Battery
VCHMIN < Requested Voltage < VLIMIT
l–32 32 mV
ITOL Current Accuracy With Respect to Current Reported by Battery
4mV/RSENSE < Requested Current < ILIMIT (Min)
(Note 12)
RILIMIT = 0 (Short to GND)
RILIMIT = 10k ±1%
RILIMIT = 33k ±1%
RILIMIT = Open (or Short ILIMIT to VCC2)
l
l
l
l
–2
–4
–8
–8
2
4
8
8
mA
mA
mA
mA
f0SC Regulator Switching Frequency 255 300 345 kHz
fDO Regulator Switching Frequency in Low
Dropout Mode
Duty Cycle ≥99% 20 25 kHz
DCMAX Regulator Maximum Duty Cycle 99 99.5 %
IMAX Maximum Current Sense Threshold VITH = 2.2V 140 155 190 mV
ISNS CA1 Input Bias Current VCSP = VCSN > 5V 150 µA
CMSL CA1 Input Common Mode Low 0 V
CMSH CA1 Input Common Mode High VDCIN –0.2 V
VCL1 CL1 Turn-On Threshold
C-Grade (Note 6)
I-Grade (Note 6)
l
l
95
94
90
100
100
100
105
108
108
mV
mV
mV
TG tr
TG tr
TGATE Transition Time:
TGATE Rise Time
TGATE Fall Time
CLOAD = 3300pF, 10% to 90%
CLOAD = 3300pF, 10% to 90%
50
50
90
90 ns
ns
BG tr
BG tf
BGATE Transition Time
BGATE Rise Time
BGATE Fall Time
CLOAD = 3300pF, 10% to 90%
CLOAD = 3300pF, 10% to 90%
50
40
90
80
ns
ns
The ldenotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA= 25°C (Note 6). VDCIN = 20V, VBAT1 = 12V, VBAT2 = 12V, VVDDS = 3.3V,
VVCC2 = 5.2V unless otherwise noted.

LTC1760
4
1760fc
For more information www.linear.com/LTC1760
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Trip Points
VTR DCDIV/LOPWR Threshold VDCDIV or VLOPWR Falling
C-Grade (Note 6)
I-Grade (Note 6)
l
l
1.166
1.162
1.19
1.19
1.215
1.215
V
V
VTHYS DCDIV/LOPWR Hysteresis Voltage VDCDIV or VLOPWR Rising 30 mV
IBVT DCDIV/LOPWR Input Bias Current VDCDIV or VLOPWR = 1.19V 20 200 nA
VTSC Short-Circuit Comparator Threshold VSCP – VSCN, VCC ≥ 5V
C-Grade (Note 6)
I-Grade (Note 6)
l
l
90
88
100
100
115
115
mV
mV
VFTO Fast PowerPath Turn-Off Threshold VDCDIV Rising from VCC 6 7 7.9 V
VOVSD Overvoltage Shutdown Threshold as a
Percent of Programmed Charger Voltage
VSET Rising from 0.8V until TGATE and BGATE
Stop Switching
107 %
DACs
IRES IDAC Resolution Guaranteed Monotonic 10 Bits
tIP
tILOW
IDAC Pulse Period:
Normal Mode
Wake-Up Mode
6
10
50
15
µs
ms
Charging Current Granularity RILIMIT = 0 (Short ILIMIT to GND)
RILIMIT = 10k ±1%
RILIMIT = 33k ±1%
RILIMIT = Open (or Short ILIMIT to VCC2 )
1
2
4
4
mA
mA
mA
mA
IWAKE_UP Wake-Up Charging Current (Note 5) 60 80 100 mA
ILIMIT Charging Current Limit C-Grade (Note 6)
RILIMIT = 0 (Short ILIMIT to GND)
RILIMIT = 10k ±1%
RILIMIT = 33k ±1%
RILIMIT = Open (or Short ILIMIT to VCC2 )
I-Grade (Note 6)
RILIMIT = 0 (Short ILIMIT to GND)
RILIMIT = 10k ±1%
RILIMIT = 33k ±1%
RILIMIT = Open (or Short ILIMIT to VCC2 )
l
l
l
l
l
l
l
l
980
1960
2490
3920
930
1870
2380
3750
1000
2000
3000
4000
1000
2000
3000
4000
1070
2140
3210
4280
1110
2220
3320
4430
mA
mA
mA
mA
mA
mA
mA
mA
VRES VDAC Resolution Guaranteed Monotonic (5V < VBAT < 25V) 11 Bits
VSTEP VDAC Granularity 16 mV
VLIMIT Charging Voltage Limit
(Note 7)
RVLIMIT = 0 (Short VLIMIT to GND)
RVLIMIT = 10k ±1%
RVLIMIT = 33k ±1%
RVLIMIT = 100k ±1%
RVLIMIT = Open (or Short VLIMIT to VCC2 )(Note 13)
l
l
l
l
l
8400
12608
16832
21024
8432
12640
16864
21056
32768
8464
12672
16896
21088
mV
mV
mV
mV
mV
Charge MUX Switches
tONC GCH1/GCH2 Turn-On Time VGCHX – VSCHX > 3V, CLOAD = 3000pF 5 10 ms
tOFFC GCH1/GCH2 Turn-Off Time VGCHX – VSCHX < 1V, from Time of
VCSN < VBATX – 30mV, CLOAD = 3000pF
15 µs
VCON CH Gate Clamp Voltage
GCH1
GCH2
ILOAD = 1µA
VGCH1 – VSCH1
VGCH2 – VSCH2
5
5
5.8
5.8
7
7
V
V
ELECTRICAL CHARACTERISTICS
The ldenotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA= 25°C (Note 6). VDCIN = 20V, VBAT1 = 12V, VBAT2 = 12V, VVDDS = 3.3V,
VVCC2 = 5.2V unless otherwise noted.

LTC1760
5
1760fc
For more information www.linear.com/LTC1760
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VCOFF CH Gate Off Voltage
GCH1
GCH2
ILOAD =10µA
VGCH1 – VSCH1
VGCH2 – VSCH2
–0.8
–0.8
–0.4
–0.4
0
0
V
V
VTOC CH Switch Reverse Turn-Off Voltage VBATX – VCSN, 5V ≤ VBATX ≤ 28V
C-Grade (Note 6)
I-Grade (Note 6)
l
l
5
2
20
20
40
40
mV
mV
VFC CH Switch Forward Regulation Voltage VCSN – VBATX,5V ≤ VBATX ≤ 28V l15 35 60 mV
IOC(SRC)
IOC(SNK)
GCH1/GCH2 Active Regulation:
Max Source Current
Max Sink Current
VGCHX – VSCHX = 1.5V
–2
2
µA
µA
VCHMIN BATX Voltage Below Which
Charging is Inhibited
(Note 14) 3.5 4.7 V
PowerPath Switches
tD LY Blanking Period after UVLO Trip Switches Held Off 250 ms
tPPB Blanking Period after LOPWR Trip Switches in 3-Diode Mode 1 sec
tONPO GB1O/GB2O/GDCO Turn-On Time VGS < –3V, from Time of Battery/DC
Removal, or LOPWR Indication, CLOAD = 3000pF
l5 10 µs
tOFFPO GB1O/GB2O/GDCO Turn-Off Time VGS > –1V, from Time of Battery/DC
Removal, or LOPWR Indication, CLOAD = 3000pF
l3 7 µs
VPONO Output Gate Clamp Voltage
GB1O
GB2O
GDCO
ILOAD = 1µA
Highest (VBAT1 or VSCP) – VGB1O
Highest (VBAT2 or VSCP) – VGB2O
Highest (VDCIN or VSCP) – VGDCO
4.75
4.75
4.75
6.25
6.25
6.25
7
7
7
V
V
V
VPOFFO Output Gate Off Voltage
GB1O
GB2O
GDCO
ILOAD = –25µA
Highest (VBAT1 or VSCP) – VGB1O
Highest (VBAT2 or VSCP) – VGB2O
Highest (VDCIN or VSCP) – VGDCO
0.18
0.18
0.18
0.25
0.25
0.25
V
V
V
VTOP PowerPath Switch Reverse
Turn-Off Voltage
VSCP – VBATX or VSCP – VDCIN
6V ≤ VSCP ≤ 28V
C-Grade (Note 6)
I-Grade (Note 6)
l
l
5
2
20
20
60
60
mV
mV
VFP PowerPath Switch Forward
Regulation Voltage
VBATX – VSCP or VDCIN – VSCP
6V ≤ VSCP ≤ 28V
l0 25 50 mV
IOP(SRC)
IOP(SNK)
GDCI/GB1I/GB2I Active Regulation:
Source Current
Sink Current
(Note 3)
–4
75
µA
µA
tONPI Gate B1I/B2I/DCI Turn-On Time VGS < –3V, CLOAD = 3000pF (Note 4) 300 µs
tOFFPI Gate B1I/B2I/DCI Turn-Off Time VGS > –1V, CLOAD = 3000pF (Note 4) 10 µs
VPONI Input Gate Clamp Voltage
GB1I
GB2I
GDCI
ILOAD = 1µA
Highest (VBAT1 or VSCP) – VGB1I
Highest (VBAT2 or VSCP) – VGB2I
Highest (VDCIN or VSCP) – VGDCI
4.75
4.75
4.75
6.7
6.7
6.7
7.5
7.5
7.5
V
V
V
VPOFFI Input Gate Off Voltage
GB1I
GB2I
GDCI
ILOAD = –25µA
Highest (VBAT1 or VSCP) – VGB1I
Highest (VBAT2 or VSCP) – VGB2I
Highest (VDCIN or VSCP) – VGDCI
0.18
0.18
0.18
0.25
0.25
0.25
V
V
V
ELECTRICAL CHARACTERISTICS
The ldenotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA= 25°C (Note 6). VDCIN = 20V, VBAT1 = 12V, VBAT2 = 12V, VVDDS = 3.3V,
VVCC2 = 5.2V unless otherwise noted.

LTC1760
6
1760fc
For more information www.linear.com/LTC1760
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Thermistor
Thermistor Trip
COLD-RANGE to OVER-RANGE
CLOAD(MAX) = 300pF (Note 9)
R1A = R2A = 1130Ω ±1%
R1B = R2B = 54900Ω ±1%
l95 100 105 kΩ
Thermistor Trip
IDEAL-RANGE to COLD-RANGE
CLOAD(MAX) = 300pF (Note 9)
R1A = R2A = 1130Ω ±1%
R1B = R2B = 54900Ω ±1%
l28.5 30 32.5 kΩ
Thermistor Trip
HOT-RANGE to IDEAL-RANGE
CLOAD(MAX) = 300pF (Note 9)
R1A = R2A = 1130Ω ±1%
R1B = R2B = 54900Ω ±1%
C-Grade (Note 6)
I-Grade (Note 6)
l
l
2.85
2.83
3
3
3.15
3.15
kΩ
kΩ
Thermistor Trip
UNDER-RANGE to HOT-RANGE
CLOAD(MAX) = 300pF (Note 9)
R1A = R2A = 1130Ω ±1%
R1B = R2B = 54900Ω ±1%
l425 500 575 Ω
Logic Levels
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Low Voltage (VIL)
l0.8 v
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input High Voltage (VIH)
l2.1 v
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Leakage Current
VSDA, VSCL, VSDA1, VSCL1,
VSDA2, VSCL2 = 0.8V
l–5 5 µA
SCL/SCL1/SCL2/SDA/SDA1/
SDA2 Input Leakage Current
VSDA, VSCL, VSDA1, VSCL1, VSDA2,
VSCL2 = 2.1V
l–5 5 µA
IPULLUP SCL1/SDA1/SCL2/SDA2 Pull-Up
Current When Not Connected to
SMBus Host
VSCL1, VSDA1, VSCL2, VSDA2 = 0.4V
VVCC2 = 4.85V and 5.55V (Current is Through
Internal Series Resistor and Schottky to VCC2)
165 220 350 µA
SCL1/SDA1/SCL2/SDA2
Series Impedance to Host SMBus
VSDA1, VSCL1, VSDA2, VSCL2 = 0.8V l300 Ω
SCL/SDA Output Low Voltage (VOL).
LTC1760 Driving the Pin
IPULLUP = 350µA l0.4 V
SCL1/SDA1/SCL2/SDA2 Pullup
Output Low Voltage (VOL).
LTC1760 Driving the Pin with Battery
SMBus not Connected to Host SMBus
IPULLUP Internal to LTC1760 l0.4 V
SCL1/SDA1/SCL2/SDA2
Output Low Voltage (VOL).
LTC1760 Driving the Pin with Battery
SMBus Connected to Host SMBus
IPULLUP = 350µA on Host Side l0.4 V
SCL/SCL1/SCL2/SDA/SDA1/ SDA2/
SMBALERT Power Down Leakage
VVCC2 = 0V, VVDDS = 0V,
VSCL, VSCL1, VSCL2, VSDA,
VSDA1, VSDA2, VSMBALERT = 5.5V
l2 µA
SMBALERT Output Low Voltage (VOL) IPULLUP = 500µA l0.4 V
SMBALERT Output Pull-Up Current VSMBALERT = 0.4V 3.5 10 17.5 µA
VIL_VDDS
VIH_VDDS
VDDS Input Low Voltage (VIL)
VDDS Input High Voltage (VIH)
VDDS Operating Voltage
VDDS Operating Current
VSCL, VSDA = VVDDS , VVDDS = 5V
l
l
l
2.6
3
1.5
5.5
18
V
V
V
µA
VIL_MODE MODE Input Low Voltage (VIL) VVCC2 = 4.85V lVVCC2 •0.3 V
ELECTRICAL CHARACTERISTICS
The ldenotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA= 25°C (Note 6). VDCIN = 20V, VBAT1 = 12V, VBAT2 = 12V, VVDDS = 3.3V,
VVCC2 = 5.2V unless otherwise noted.

LTC1760
7
1760fc
For more information www.linear.com/LTC1760
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIH_MODE MODE Input High Voltage (VIH) VVCC2 = 4.85V lVVCC2 •0.7 V
MODE Input Current (IIH) MODE = VVCC2 • 0.7V, VVCC2 = 4.85V l–1 1 µA
MODE Input Current (IIL) MODE = VVCC2 • 0.3V, VVCC2 = 4.85V l–1 1 µA
Charger Timing
tTIMEOUT Timeout for Wake-Up Charging and
Controlled Charging
l140 175 210 sec
tQUERY Sampling Rate Used by the LTC1760 to
Update Charging Parameters
1 sec
SMBus Timing
SCL Serial-Clock High Period(tHIGH) At IPULLUP = 350µA, CLOAD = 150pF (Note 8) l4 µs
SCL Serial-Clock Low Period (tLOW) At IPULLUP = 350µA, CLOAD = 150pF (Note 8) l4.7 µs
SDA/SCL Rise Time (tr) CLOAD = 150pF, RPU = 9.31k (Note 8) l1000 ns
SDA/SCL Fall Time (tf) CLOAD = 150pF, RPU = 9.31k (Note 8) l300 ns
SMBus Accelerator Trip Voltage Range l0.8 1.42 V
Start-Condition Setup Time (tSU:STA)l4.7 µs
Start-Condition Hold Time (tHD:STA)l4 µs
SDA to SCL Rising-Edge
Setup Time (tSU:DAT)
l250 ns
SDA to SCL Falling-Edge Hold Time,
Slave Clocking in Data (tHD:DAT)
l300 ns
tTIMEOUT_
SMB
The LTC1760 will Release the SMBus
and Terminate the Current Master or
Slave Command if the Command is not
Completed Before this Time
l25 35 ms
ELECTRICAL CHARACTERISTICS
The ldenotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at TA= 25°C (Note 6). VDCIN = 20V, VBAT1 = 12V, VBAT2 = 12V, VVDDS = 3.3V,
VVCC2 = 5.2V unless otherwise noted.
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: Battery voltage must be adequate to drive gates of PowerPath
P-channel FET switches. This does not affect charging voltage of the
battery, which can be zero volts during wake-up charging.
Note 3: DCIN, BAT1, BAT2 are held at 12V and GDCI, GB1I, GB2I are
forced to 10.5V. SCP is set at 12V to measure source current at GDCI,
GB1I and GB2I. SCP is set at 11.9V to measure sink current at GDCI, GB1I
and GB2I.
Note 4: Extrapolated from testing with CL= 50pF.
Note 5: Accuracy dependent upon external sense resistor and
compensation components.
Note 6: The LTC1760 is tested under pulsed load conditions such that TJ≈
TA. The LTC1760C is guaranteed to meet specifications from 0°C to 70°C
junction temperature. Specifications over the –40°C to 85°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC1760I is guaranteed
over the –40°C to 125°C operating junction temperature range.
Note 7: Charger servos to the value reported by a Voltage() query. This is
the internal cell voltage measured by the battery electronics and may be
lower than the terminal voltage. Refer to “Operation Section 3.7” for more
information.
Note 8: CLOAD is the combined capacitance on the host’s SMBus
connection and the selected battery’s SMBus connection.
Note 9: CLOAD_MAX is the maximum allowed combined capacitance on
THxA, THxB and the battery’s SafetySignalx connections.
Note 10: Does not include current supplied by VCC to VCC2 (IVCC2_AC1 or
IVCC2_AC0)
Note 11: Measured with thermistors not present, RVLIMIT and RILIMIT
removed and SMBALERT = 1. See Applications Information section:
“Calculating IC Operating Current” for example on how to calculate total IC
operating current.
Note 12: Requested currents below 44mV/RSENSE may not servo correctly
due to charger offsets. The charging current for requested currents below
4mV/RSENSE will be between 4mV/RSENSE and (Requested Current – 8mA).
Refer to Applications Information: “Setting Charger Output Current Limit”
for values of RSENSE.
Note 13: This limit is greater than the absolute maximum for the charger.
Therefore, there is no effective limitation for the voltage when this option
is selected.
Note 14: Does not apply to Wake-Up Mode.

LTC1760
8
1760fc
For more information www.linear.com/LTC1760
TYPICAL PERFORMANCE CHARACTERISTICS
Dual Charging Batteries with
Different Charge State
Dual Battery Discharge Time vs
Sequential Battery Discharge
(Li-Ion)
Dual Battery Dischage Time vs
Sequential Battery Discharge
(NiMH)
Charging Voltage Accuracy Charging Current Accuracy
Dual Battery Charge Time vs
Sequential Battery Charging
ChargingVoltage() (mV)
4700
Voltage()–ChargingVoltage() (mV)
–10
–5
0
14428
1760 G01
–15
–20
–25 7132 9564 11996 16860
ChargingCurrent() (mA)
–20
Current()–ChargingCurrent() (mA)
–10
0
10
–15
–5
5
800 1600 2400 3200
1760 G02
40000
TIME (MINUTES)
BATTERY CURRENT (mA)
3500
3000
2500
2000
1500
1000
500
0
3500
3000
2500
2000
1500
1000
500
0
1760 G03
050 100 150 200 250 300
BAT1
CURRENT
BAT2
CURRENT
SEQUENTIAL
DUAL
BAT1
CURRENT
100
MINUTES
BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020)
REQUESTED CURRENT = 3A
REQUESTED VOLTAGE = 12.3V
MAX CHARGER CURRENT = 4.1A
BAT2
CURRENT
BAT2
VOLTAGE
BAT2
CURRENT
BAT1
CURRENT
BAT1
VOLTAGE
BAT1 INITIAL CAPACITY = 0%
BAT2 INITIAL CAPACITY = 90%
PROGRAMMED CHARGER CURRENT = 3A
PROGRAMMED CHARGER VOLTAGE = 16.8V
TIME (MINUTES)
0
BATTERY VOLTAGE (V)
120
1760 G04
40 80 160
17.0
16.5
16.0
15.5
15.0
14.5
14.0
13.5 20 60 100 140
BATTERY CURRENT (mA)
3500
3000
2500
2000
1500
1000
500
0
TIME (MINUTES)
0
BATTERY VOLTAGE (V)
120
12.0
11.0
10.0
9.0
8.0
12.0
11.0
10.0
9.0
8.0
1760 G05
20 180
40 60 80 100 140 160
BAT1
VOLTAGE
BAT1
VOLTAGE
DUAL
SEQUENTIAL
BAT2
VOLTAGE
BAT2
VOLTAGE
BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020)
LOAD CURRENT = 3A
11
MINUTES
TIME (MINUTES)
0120
20 40 60 80 100 140
BATTERY VOLTAGE (V)
15
14
13
12
11
10
15
14
13
12
11
10
1760 G06
BAT2
VOLTAGE
BAT2
VOLTAGE
BAT1
VOLTAGE
BAT1
VOLTAGE
BATTERY TYPE: 12V NiMH (MOLTECH NJ1020)
LOAD: 33W
16
MINUTES
DUAL
SEQUENTIAL

LTC1760
9
1760fc
For more information www.linear.com/LTC1760
Efficiency vs Charging Current Load Dump Load Regulation
TYPICAL PERFORMANCE CHARACTERISTICS
PowerPath Switching 1 and 2 SMBus Accelerator Operation
IOUT (A)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
0.025 0.10
1760 G07
20
80
90
60
0.50 2.5 4.0
TIME (ms)
–4 –2
BAT1 VOLTAGE (V)
14
12
10
8
6
4
2
0
1760 G08
42 10 12 14 16
06 8
VIN = 20V
VDAC = 12.29V
IDAC = 3000mA
LOAD CURRENT = 1A
TA= 25°C
BAT1
OUTPUT
LOAD
CONNECTED
LOAD
DISCONNECTED
CHARGE CURRENT (mA)
0
BAT1 VOLTAGE (V)
4000
1760 G09
1000 2000 3000
12.4
12.3
12.2
12.1
12.0
11.9
11.8
11.7
11.6
VIN = 20V
VDAC = 12.288V
IDAC = 4000mA
TA= 25°C
TIME (µs)
16
15
14
13
12
11
10
9
8
7
6
LOAD VOLTAGE (V)
1960 G10
–50 –40 –30 –10 010 20 30 40 50
–20
CLOAD = 20F
ILOAD = 0.8A
TA= 25°C
LOPWR
THRESHOLD
1µs/DIV
1760 G11
5V
0V
RPULLUP = 15k
LTC1760
VCC = 5V
CLD = 200pF
TA= 25°C
PIN FUNCTIONS
Input Power Related
SCN (Pin 4): PowerPath Current Sensing Negative Input.
This pin should be connected directly to the “bottom”
(output side) of the sense resistor, RSC, in series with the
three PowerPath switch pairs, for detecting short-circuit
current events. Also powers the LTC1760 internal circuitry
when all other sources are absent.
SCP (Pin 5):PowerPath Current Sensing Positive Input.
This pin should be connected directly to the “top” (switch
side) of the sense resistor, RSC, in series with the three
PowerPath switch pairs, for detecting short-circuit cur-
rent events.
GDCO (Pin 6):DCIN Output Switch Gate Drive. Together
with GDCI, this pin drives the gate of the P-channel switch
in series with the DCIN input switch.
GDCI (Pin 7):DCIN Input Switch Gate Drive. Together with
GDCO, this pin drives the gate of the P-channel switch
connected to the DCIN input.

LTC1760
10
1760fc
For more information www.linear.com/LTC1760
GB1O (Pin 8):BAT1 Output Switch Gate Drive. Together
with GB1I, this pin drives the gate of the P-channel switch
in series with the BAT1 input switch.
GB1I (Pin 9): BAT1 Input Switch Gate Drive. Together with
GB1O, this pin drives the gate of the P-channel switch
connected to the BAT1 input.
GB2O (Pin 10):BAT2 Output Switch Gate Drive. Together
with GB2I, this pin drives the gate of the P-channel switch
in series with the BAT2 input switch.
GB2I (Pin 11):BAT2 Input Switch Gate Drive. Together
with GB2O, this pin drives the gate of the P-channel switch
connected to the BAT2 input.
CLP (Pin 36):The Positive Input to the Supply Current
LimitingAmplifierCL1.The threshold issetat100mV above
the voltage at the DCIN pin. When used to limit supply
current, a filter is needed to filter out the switching noise.
Battery Charging Related
VSET (Pin 13):The Tap Point of a Programmable Resistor
Divider which Provides Battery Voltage Feedback to the
Charger. A capacitor from CSN to VSET and from VSET to
GND provide necessary compensation and filtering for
the voltage loop.
ITH (Pin 14):The Control Signal of the Inner Loop of the
Current Mode PWM. Higher ITH voltage corresponds to
higher charging current in normal operation. A capacitor
of at least 0.1µF to GND filters out PWM ripple. Typical
full-scale output current is 30µA. Nominal voltage range
for this pin is 0V to 2.4V.
ISET (Pin 15):A capacitor from ISET to GND is required to
filterhigherfrequencycomponentsfromthedelta-sigmaIDAC.
ILIMIT (Pin 32):An external resistor (RILIMIT) is connected
between this pin and GND. The value of the external resis-
tor programs the range and resolution of the programmed
charger current.
VLIMIT (Pin 33): An external resistor (RVLIMIT)is connected
between this pin and GND. The value of the external resis-
tor programs the range and resolution of the voltage DAC.
CSN (Pin 34): Current Amplifier CA1 Input. Connect this
to the common output of the charger MUX switches.
CSP (Pin 35):Current Amplifier CA1 Input. This pin and
the CSN pin measure the voltage across the charge cur-
rent sense resistor, RSENSE, to provide the instantaneous
current signals required for both peak and average current
mode operation.
COMP1 (Pin 37):The Compensation Node for the Am-
plifier CL1. A capacitor is required from this pin to GND
if input current amplifier CL1 is used. At input adapter
current limit, this node rises to 1V. By forcing COMP1 to
GND, amplifier CL1 will be defeated (no adapter current
limit). COMP1 can source 10µA.
BGATE (Pin 39):Drives the gate of the bottom external
MOSFET of the battery charger buck converter.
SW (Pin 42):PWM Switch Node. Connected to the source
of the top external MOSFET. Used as reference for top
gate driver.
BOOST (Pin 43):Supply to Topside Floating Driver. The
bootstrap capacitor is returned to this pin. Voltage swing
at this pin is from a diode drop below VCC to (DCIN + VCC).
TGATE (Pin 44):Drivesthegate ofthetop externalMOSFET
of the battery charger buck converter.
SCH1 (Pin 45), SCH2 (Pin 48):Charger MUX N-Channel
Switch Source Returns. These two pins are connected to
the sources of the back-to-back switch pairs Q3/Q4 and
Q9/Q10 (see Typical Applications). A small pull-down cur-
rent source returns these nodes to 0V when the switches
are turned off.
GCH1 (Pin 46), GCH2 (Pin 47):Charger MUX N-Channel
Switch Gate Drives. These two pins drive the gates of the
back-to-back switch pairs, Q3/Q4 and Q9/Q10, between
the charger output and the two batteries (see Typical
Applications).
External Power Supply Pins
VPLUS (Pin 1):Supply. The VPLUS pin is connected via
four internal diodes to the DCIN, SCN, BAT1, and BAT2
pins. Bypass this pin with a 0.1µF capacitor and a 1µF
capacitor (see Typical Applications for complete circuit).
BAT1 (Pin 3), BAT2 (Pin 2):These two pins are the inputs
from the two batteries for power to the LTC1760.
PIN FUNCTIONS

LTC1760
11
1760fc
For more information www.linear.com/LTC1760
LOPWR (Pin 12): LOPWR Comparator Input from SCN
External Resistor Divider to GND. If the voltage at LOPWR
pin is lower than the LOPWR comparator threshold, then
system power has failed and power is autonomously
switched to a higher voltage source, if available.
DCDIV (Pin 16):External DC Source Comparator Input
from DCIN External Resistor Divider to GND. If the
voltage at DCDIV pin is above the DCDIV comparator
threshold, then the AC_PRESENT bit is set and the wall
adapter power is considered to be adequate to charge
the batteries. If DCDIV rises more than 1.8V above VCC,
then all of the power path switches are latched off until
all power is removed. A capacitor from DCDIV to GND is
recommendedtopreventnoise-inducedfalse emergency
turn-offconditions frombeing detected. Referto “Section
8.3” and “Typical Application”.
DCIN (Pin 41):Supply. ExternalDC power source.A0.1µF
bypass capacitor must be connected to this pin as close
as possible. No series resistance is allowed, since the
adapter current limit comparator input is also this pin.
Internal Power Supply Pins
VDDS (Pin 20):Power Supply for SMBus Accelerators.
Also used in conjunction with MODE pin to modify the
LTC1760 operating mode.
GND (Pin 24): Ground for Low Power Circuitry.
VCC2 (Pin 25): Power Supply is used Primarily to Power
Internal Logic Circuitry. Must be connected to VCC.
PGND (Pin 38):High Current Ground Return for BGATE
Driver.
VCC (Pin 40):Internal Regulator Output. Bypass this
output with at least a 2µF to 4.7µF capacitor. Do not use
this regulator output to supply external circuitry except
as shown in the application circuit.
SBS Interface Pins
SCL2 (Pin 17):SMBus Clock Signal to Smart Battery 2. Do
not connect to an external pull-up. The LTC1760 connects
this pin to an internal pull-up (IPULLUP) when required.
SCL (Pin 18):SMBus Clock Signal to SMBus Host. Also
used to determine flashing rate for stand-alone charge indi-
cators. Requires an external pullup to VDDS (normal SMBus
operating mode). Connected to internal SMBus accelerator.
SCL1 (Pin 19):SMBus Clock Signal to Smart Battery 1. Do
not connect to an external pull-up. The LTC1760 connects
this pin to an internal pull-up (IPULLUP) when required.
SDA2 (Pin 21):SMBus Data Signal to Smart Battery 2. Do
not connect to an external pull-up. The LTC1760 connects
this pin to an internal pull-up (IPULLUP) when required.
SDA (Pin 22):SMBus Data Signal to SMBus Host. Also
used to indicate charging status of Battery 2. Requires
an external pullup to VDDS. Connected to internal SMBus
accelerator.
SDA1 (Pin 23):SMBus Data Signal to Smart Battery 1. Do
not connect to an external pull-up. The LTC1760 connects
this pin to an internal pull-up (IPULLUP) when required.
MODE (Pin 26):Used in conjunction with VDDS to allow
SCL,SDA andSMBALERT to indicate chargingstatus. May
also be used as a hardware charge inhibit.
TH2B (Pin 27):Thermistor Force/Sense Connection
to Smart Battery 2 SafetySignal. Connect to Battery 2
thermistor through resistor network shown in “Typical
Application.”
TH2A (Pin 28):Thermistor Force/Sense Connection
to Smart Battery 2 SafetySignal. Connect to Battery 2
thermistor through resistor network shown in “Typical
Application.”
SMBALERT (Pin 29):Active Low Interrupt Pin. Signals
SMBus Host that there has been a change of status in
battery or AC presence. Open drain with weak current
source pull-up to VCC2 (with Schottky to allow it to be
pulled to 5V externally). Also used to indicate charging
status of Battery 1.
TH1A (Pin 30):Thermistor Force/Sense Connection
to Smart Battery 1 SafetySignal. Connect to Battery 1
thermistor through resistor network shown in “Typical
Application.”
TH1B (Pin 31):Thermistor Force/Sense Connection
to Smart Battery 1 SafetySignal. Connect to Battery 1
thermistor through resistor network shown in “Typical
Application.”
PIN FUNCTIONS

LTC1760
12
1760fc
For more information www.linear.com/LTC1760
BLOCK DIAGRAM
SHORT CIRCUIT
SEQUENCER
10-BIT ∆Σ
CURRENT DAC
LIMIT
DECODER
PowerPath
CONTROLLER
SMBus
INTERFACE
CHARGE
+
–
+
–
–
–
–
–
11-BIT ∆Σ
VOLTAGE DAC
100Ω
100mV
SWB1
DRIVER
CHARGE
PUMP
SWB2
DRIVER
SWDC
DRIVER
CSN
+
–
ON
+
–
ON
DCIN
GCH1
SCH2
GCH2
SCH1
TGATE
PGND
BGATE
SW
BAT1
GND
DCDIV
LOPWR
VCC
VCC2
DCIN
DCIN
VSET
VPLUS
BAT2
OSCILLATOR
LOW DROP
DETECT TON
BOOST
BGATE
VCC
PWM
LOGIC
+
+
+
+
Q
S
R
100mV
CLP
+
40mV
+
–
15
SCN
GB1I GB1O GB2I GB2O GDCI GDCO
SCP
SCN
CSP
TH2B
TH2A
TH1B
TH1A
CSN
ISET
CA1
3k
3k
0.8V
BUFFERED ITH
gm= 1.4m
gm= 0.4m
Ω
gm= 1.4m
Ω
IREV
ICMP
ITH
COMP1
CSP-CSN
3kΩ
36
38
39
42
44
43
13
41
16
12
40
24
25
1
2
3
48
47
45
46
9 8 11 10 7 6
37 14
5
4
MODE
26
30
31
28
27
15
35
34
CL1
CA2
VCC
REGULATOR SAFETY
SIGNAL
DECODER
1.19V
0.86V
CSN 0V
400k
EA
0.8V
AC_PRESENT
ILIMIT
32
VLIMIT
33
1760 BD
3mV
SDA2
SCL2
SDA1
SCL1
SDA
SCL
VDDS
VCC2
18
22
19
23
17
21
20
SMBALERT
29
10µA
+
–
+
–
+
–
–

LTC1760
13
1760fc
For more information www.linear.com/LTC1760
(For Operation Section)
TABLE OF CONTENTS
1 Overview................................................................................................................................................................................................... 14
2 The SMBus Interface................................................................................................................................................................................. 14
2.1 SMBus Interface Overview................................................................................................................................................................ 14
2.3 Description of Supported SMBus Functions ..................................................................................................................................... 17
2.3.1 BatterySystemState() (0×01) .................................................................................................................................................. 17
2.3.2 BatterySystemStateCont() (0×02) ........................................................................................................................................... 18
2.3.3 BatterySystemInfo() (0×04) .................................................................................................................................................... 19
2.3.4 LTC() (0×3C) ........................................................................................................................................................................... 20
2.3.5 BatteryMode() (0×03) ............................................................................................................................................................ 20
2.3.6 Voltage() (0×09)...................................................................................................................................................................... 20
2.3.7 Current() (0×0A) ..................................................................................................................................................................... 21
2.3.8 ChargingCurrent() (0×14) ....................................................................................................................................................... 21
2.3.9 ChargingVoltage() (0×15) ....................................................................................................................................................... 21
2.3.10 AlarmWarning() (0×16)........................................................................................................................................................... 21
2.3.11 AlertResponse() ...................................................................................................................................................................... 22
2.4 SMBus Dual Port Operation.............................................................................................................................................................. 22
2.5 LTC1760 SMBus Controller Operation............................................................................................................................................... 23
2.6 LTC1760 SMBALERT Operation ........................................................................................................................................................ 26
3 Charging Algorithm Overview ................................................................................................................................................................... 26
3.1 Wake-Up Charging Initiation ............................................................................................................................................................. 26
3.2 Wake-Up Charging Termination ........................................................................................................................................................ 26
3.3 Wake-Up Charging Current and Voltage Limits................................................................................................................................. 27
3.4 Controlled Charging Initiation ........................................................................................................................................................... 27
3.5 Controlled Charging Termination ...................................................................................................................................................... 27
3.6 Controlled Charging Current Programming ...................................................................................................................................... 28
3.6.1 Current Limits When Charging A Single Battery...................................................................................................................... 28
3.6.2 Current Limits When Charging Two Batteries (TURBO Mode Disabled) .................................................................................. 28
3.6.3 Current Limits When Charging Two Batteries (TURBO Mode Enabled).................................................................................... 29
3.7 Controlled Charging Voltage Programming....................................................................................................................................... 29
4 System Power Management Algorithm and Battery Calibration................................................................................................................ 29
4.1 Turning Off System Power ................................................................................................................................................................ 29
4.2 Power-By Algorithm When No Battery is Being Calibrated................................................................................................................ 29
4.3 Power-By Algorithm When a Battery is Being Calibrated................................................................................................................... 30
4.4 Power-By Reporting.......................................................................................................................................................................... 30
5 Battery Calibration (Conditioning)............................................................................................................................................................. 30
5.1 Selecting a Battery to be Calibrated ................................................................................................................................................. 30
5.2 Initiating Calibration of Selected Battery ........................................................................................................................................... 31
5.3 Terminating Calibration of Selected Battery ...................................................................................................................................... 31
6 MODE Pin Operation................................................................................................................................................................................. 31
6.1 Standalone Charge Indication ........................................................................................................................................................... 31
6.2 Hardware Charge Inhibit ................................................................................................................................................................... 32
6.3 Charging When SCL And SDA Are Low............................................................................................................................................. 32
6.4 Charging With an SMBus Host ......................................................................................................................................................... 32
7 Battery Charger Controller ........................................................................................................................................................................ 32
7.1 Charge MUX Switches ...................................................................................................................................................................... 33
7.2 Dual Charging ................................................................................................................................................................................... 33
8 PowerPath Controller................................................................................................................................................................................ 33
8.1 Autonomous PowerPath Switching................................................................................................................................................... 34
8.2 Short-Circuit Protection .................................................................................................................................................................... 34
8.3 Emergency Turn-Off.......................................................................................................................................................................... 34
8.4 Power-Up Strategy............................................................................................................................................................................ 34
9 The Voltage DAC Block ............................................................................................................................................................................. 35
10 The Current DAC Block ............................................................................................................................................................................. 35

LTC1760
14
1760fc
For more information www.linear.com/LTC1760
OPERATION
1 Overview
The LTC1760 is composed of an SMBus interface with
dual port capability, a sequencer for managing system
power and the charging and discharging of two batteries,
a battery charger controller, charge MUX controller, Pow-
erPath controller, a 10-bit current DAC (IDAC) and 11-bit
voltage DAC (VDAC). When coupled with optional system
software for generating composite battery information,
it forms a complete Smart Battery System Manager for
charging and selecting two smart batteries. The battery
charger is controlled by the sequencer which uses a Level
3 SMBus interface to read ChargingVoltage(), Voltage(),
ChargingCurrent(),Current(), Alarm()and BatteryMode().
This information, together with thermistor measurements
allows the sequencer to select the charging battery and
safely servo on voltage and current. Charging can be
accomplished only if the voltage at DCDIV indicates that
sufficient voltage is available from the input power source,
usually an AC adapter. The charge MUX, which selects
the battery to be charged, is capable of charging both
batteries simultaneously. The charge MUX switch drivers
are configured to allow charger current to share between
the two batteries and to prevent current from flowing in
a reverse direction in the switch. The amount of current
that each battery receives will depend upon the relative
capacity of each battery and the battery voltage. This can
resultin significantlyshorter charging times(up to50% for
Li-Ion batteries) than sequential charging of each battery.
The sequencer also selects which of the pairs of PFET
switches will provide power to the system load. If the
system voltage drops below the threshold set by the
LOPWR resistor divider, then all of the output-side PFETs
are turned on quickly. The input-side PFETs act as diodes
in this mode and power is taken from the highest voltage
source available at the DCIN, BAT1, or BAT2 inputs. The
input-sidePowerPathswitchdriverthatis deliveringpower
then closes its input switch to reduce the power dissipa-
tion in the PFET bulk diode. In effect, this system provides
diode-like behavior from the FET switches, without the
attendant high power dissipation from diodes. The Host
is informed of this 3-Diode mode status when it polls the
PowerPath status register via the SMBus interface. High
speed PowerPath switching at the LOPWR trip point is
handled autonomously.
Simultaneous discharge of both batteries is supported.
The switch drivers prevent reverse current flow in the
switches and automatically discharge both batteries into
the load, sharing current according to the relative capacity
of the batteries. Simultaneous dual discharge can increase
battery operating time by up to 10% by reducing losses
in the switches and reducing internal battery losses as-
sociated with high discharge rates.
2 The SMBus Interface
2.1 SMBus Interface Overview
The SMBus interface allows the LTC1760 to communi-
cate with two batteries and the SMBus Host. The SMBus
Interface supports true dual port operation by allowing
the SMBus Host to be connected to the SMBus of either
battery. The LTC1760 is able to operate as an SMBus
Master or Slave device. The LTC1760 SMBUS address is
0×14 (8-bit format).
References:
Smart Battery System Manager Specification:Revision
1.1, SBS Implementers Forum.
Smart Battery Data Specification:Revision 1.1, SBS Imp-
lementers Forum.
Smart Battery Charger Specification:Revision 1.1, SBS Imp-
lementers Forum
SystemManagement BusSpecification:Revision 1.1,SBS
Implementers Forum
I2C-Bus and How to Use it: V1.0, Philips Semiconductor.
(Refer to Block Diagram and Typical Application Figure)

LTC1760
15
1760fc
For more information www.linear.com/LTC1760
2.2 Data Bit Definition of Supported SMBus Functions.
Function
LTC1760
SMBus
Mode
Access
SMBus
Address
Command
Code
Data
Type
Data Bit or Nibble Definition/Allowed Values
(See section 2.3 for Details)
D15 D14 D13 D12 D11 D10 D09 D08 D07 D06 D05 D04 D03 D02 D01 D00
BatterySystemState() Slave Read/
Write
7-bit:
0001_010b
8-bit:
0×14
0×01 Status/
Control
SMB_BAT4
SMB_BAT3
SMB_BAT2
SMB_BAT1
POWER_BY_BAT4
POWER_BY_BAT3
POWER_BY_BAT2
POWER_BY_BAT1
CHARGE_BAT4
CHARGE_BAT3
CHARGE_BAT2
CHARGE_BAT1
PRESENT_ BAT4
PRESENT_ BAT3
PRESENT_ BAT2
PRESENT_ BAT1
0 0 0/1 0/1 0 0 0/1 0/1 0 0 0/1 0/1 0 0 0/1 0/1
BatterySystemStateCont() Slave Read/
Write
7-bit:
0001_010b
8-bit:
0×14
0×02 Status/
Control
RESERVED
RESERVED
RESERVED
RESERVED
CALIBRATE_BAT4
CALIBRATE_BAT3
CALIBRATE_BAT2
CALIBRATE_BAT1
RESERVED
CALIBRATE
CHARGER_POR
CHARGING_INHIBIT
CALIBRATE_REQUEST
CALIBRATE_REQUEST_SUPPORT
POWER_NOT_GOOD
AC_PRESENT
0 0 0 0 0 0 0/1 0/1 0 0/1 0/1 0/1 0/1 1 0/1 0/1
BatterySystemInfo() Slave Read 7-bit:
0001_010b
8-bit:
0×14
0×04 Status
RESERVED
RESERVED BATTERY
SYSTEM
REVISION
BATTERY
SUPPORTED
0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 1
LTC() Slave Read/
Write
7-bit:
0001_010b
8-bit:
0×14
0×3C Status/
Control
POWER_OFF
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
TURBO
RESERVED
RESERVED
RESERVED
LTC_VERSION3
LTC_VERSION2
LTC_VERSION1
LTC_VERSION0
0/1 0 0 0 0 0 0 1 0/1 0 0 0 0 0 0 1
BatteryMode() Master Read 7-bit:
0001_011b
8-bit:
0×16
0×03 Status
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
CONDITION_FLAG
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
OPERATION

LTC1760
16
1760fc
For more information www.linear.com/LTC1760
Function
LTC1760
Mode
Access
SMBus
Address
Command
Code
Data
Type
Data Bit or Nibble Definition/Allowed Values
(See section 2.3 for Details)
D15 D14 D13 D12 D11 D10 D09 D08 D07 D06 D05 D04 D03 D02 D01 D00
Current() Master Read 7-bit:
0001_011b
8-bit:
0×16
0×0A Value
IA15
IA14
IA13
IA12
IA11
IA10
IA09
IA08
IA07
IA06
IA05
IA04
IA03
IA02
IA01
IA00
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
Voltage() Master Read 7-bit:
0001_011b
8-bit:
0×16
0×09 Status/
Control
VA15
VA14
VA13
VA12
VA11
VA10
VA09
VA08
VA07
VA06
VA05
VA04
VA03
VA02
VA01
VA00
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
ChargingCurrent() Master Read 7-bit:
0001_011b
8-bit:
0×16
0×14 Status
IR15
IR14
IR13
IR12
IR11
IR10
IR09
IR08
IR07
IR06
IR05
IR04
IR03
IR02
IR01
IR00
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
ChargingVoltage() Master Read 7-bit:
0001_011b
8-bit:
0×16
0×15 Status/
Control
VR15
VR14
VR13
VR12
VR11
VR10
VR09
VR08
VR07
VR06
VR05
VR04
VR03
VR02
VR01
VR00
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
AlarmWarning() Master Read 7-bit:
0001_010b
8-bit:
0×16
0×16 Status
OVER_CHARGED
TERMINATE_CHARGE_ALARM
TERMINATE_CHARGE_RESERVED
OVER_TEMP_ALARM
TERMINATE_DISCHARGE_ALARM
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
FULLY_DISCHARGED
RESERVED
RESERVED
RESERVED
RESERVED
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
AlertResponse()
see (1)
Slave Read
Byte
7-bit:
0001_100b
8-bit:
0×18
N/A Register
ARA_ADD07
ARA_ADD06
ARA_ADD05
ARA_ADD04
ARA_ADD03
ARA_ADD02
ARA_ADD01
ARA_ADD00
0 0 0 1 0 1 0 0
(1) Read-byte format. 0×14 is returned as the interrupt address of the LTC1760.
OPERATION

LTC1760
17
1760fc
For more information www.linear.com/LTC1760
OPERATION
2.3 Description of Supported SMBus Functions
The functions are described as follows:
Function Name() (command code)
Description:
A brief description of the function.
Purpose:
The purpose of the function, and an example where ap-
propriate.
SMBus Protocol:Refer to Section 2.5 and to the SMBus
specification for more details.
Input, Output or Input/Output:A description of the data
supplied to, or returned by, the function.
Whenever the LTC1760 encounters a valid command with
invalid data, it ACKs the command, and ignores the invalid
data. For example, if an attempt is made to select Battery
1 and 2 to simultaneously communicate with the system
host, the LTC1760 will just ignore the request.
2.3.1 BatterySystemState() (0×01)
Description:
This function returns the present state of the LTC1760 and
allows access to individual batteries. The information is
broken into four nibbles that report:
Which battery is communicating with the SMBus Host
Which batteries, if any, or AC is powering the system
Which batteries are connected to the Smart Charger
Which batteries are present.
The LTC1760 provides a mechanism to notify the system
whenever there is a change in its state. Specifically, the
LTC1760provides the systemwith a notificationwhenever:
•A battery is added or removed (Polling or SMBALERT).
• AC power is connected or disconnected (Polling or
SMBALERT).
•TheLTC1760 autonomously changesthe configura-tion
of the batteries supplying power (Polling only).
•The LTC1760 autonomously changes the configuration
of the batteries being charged (Polling only).
Purpose:
Used by the SMBus Host to determine the present state
of the LTC1760 and the attached batteries. It also may be
used to determine the state of the battery system after
the LTC1760 notifies the SMBus Host of a change via
SMBALERT.
SMBus Protocol: Read or Write Word.
Input/Output:word –Refer to “Section 2.2”for bit
mapping.
SMB_BAT[4:1] Nibble
Theread/write SMB_BAT[4:1]nibbleis usedby the SMBus
Host to select with which individual battery to commu-
nicate or to determine with which individual battery it is
communicating.
For example, an application that displays the remaining
capacity of all batteries would write to this nibble to in-
dividually select each battery in turn and get its capacity.
Allowed values are:
0010b: SMBus Host is communicating with Battery 2.
0001b:SMBus Host is communicating with Battery 1.
(Power On Reset Value)
To change this nibble, set only one of the lower two bits
of this nibble high. All other values will simply be ignored.
POWER_BY_BAT[4:1] Nibble
The read only POWER_BY_BAT[4:1] nibble is used by the
SMBus Host to determine which batteries are powering
the system. All writes to this nibble will be ignored.
Allowed values are:
0011b: System powered by both Battery 2 and Battery 1
simultaneously.
0010b: System powered by Battery 2 only.
0001b: System powered by Battery 1 only.
0000b: System powered by AC adapter only.

LTC1760
18
1760fc
For more information www.linear.com/LTC1760
CHARGE_BAT[4:1] Nibble
The read only CHARGE_BAT[4:1]nibble is used by the
SMBus Host to determine which, if any, battery is being
charged. All writes to this nibble will be ignored.
Allowed values are:
0011b: Both Battery 2 and Battery 1 being charged.
0010b: Only Battery 2 is being charged.
0001b: Only Battery 1 is being charged.
0000b: No battery being charged.
An indication that multiple batteries are being charged
simultaneously does not indicate that the batteries are
being charged at the same rate or that they will complete
their charge at the same time. To actually determine
when an individual battery will be fully charged, use the
SMB_BAT[4:1] nibble to individually select the battery of
interest and read the TimeToFull() value.
PRESENT_BAT[4:1] Nibble
The read only PRESENT_BAT[4:1]nibble is used by the
SMBus Host to determine how many and which batteries
are present. All writes to this nibble will be ignored.
Allowed values are:
0011b: Both Battery 2 and Battery 1 are present.
0010b: Only Battery 2 is present.
0001b: Only Battery 1 is present.
0000b: No batteries are present.
2.3.2 BatterySystemStateCont() (0×02)
Description:
This function returns additional state information of the
LTC1760 and provides a mechanism to prohibit charging.
This command also removes any requirement for the
SMBus Host to communicate directly with the charger to
obtainACpresenceinformation.WhentheLTC1760isused,
access to the charger 8-bit address, 0×012, is blocked.
Purpose:
Used by the SMBus Host to retrieve additional state
information from the LTC1760 and the overall system
power configuration. It may also be used by the system
to prohibit any battery charging.
SMBus Protocol: Read or Write Word.
Input/Output:word - Refer to “Section 2.2”for bit
mapping
AC_PRESENT Bit
The read only AC_PRESENT bit is used to show the user
the status of AC availability to power the system. It may
be used internally by the SMBus Host in conjunction with
other information to determine when it is appropriate to
allow a battery conditioning cycle. Whenever there is a
change in the AC status, the LTC1760 asserts SMBALERT
low. In response, the system has to read this register to
determine the actual presence of AC. The LTC1760 uses
the DCDIV pin to measure the presence of AC.
Allowed values are:
1b: The LTC1760 has determined that AC is present.
0b: The LTC1760 has determined that AC is not pres-
ent.
POWER_NOT_GOOD Bit
The read only POWER_NOT_GOOD bit is used to show
that the voltage delivered to the system load is inadequate.
This is determined by the LOPWR comparator.
ThePOWER_NOT_GOOD bitwill alsobe setif theLTC1760
has detected a short circuit condition (see “Section 8.2”)
or an emergency turn-off condition (see “Section 8.3”).
Under either of these conditions the power paths will be
shut off even if battery or DC power is available.
Allowed values are:
1b: The LTC1760 has determined that the voltage
delivered to the system load is inadequate.
0b: The LTC1760 has determined that the voltage
delivered to the system load is adequate.
CALIBRATE_REQUEST_SUPPORT Bit
The read only CALIBRATE_REQUEST_SUPPORT bit is
always set high to indicate that the LTC1760 has a mecha-
nism to determine when any of the attached batteries are
in need of a calibration cycle.
OPERATION

LTC1760
19
1760fc
For more information www.linear.com/LTC1760
OPERATION
CALIBRATE_REQUEST Bit
The read only CALIBRATE_REQUEST bit is set whenever
the LTC1760 has determined that one or both of the con-
nected batteries need a calibration cycle.
Allowed values are:
1b: The LTC1760 has determined that one or both
batteries requires calibration.
0b: The LTC1760 has determined that neither battery
require calibration.
CHARGING_INHIBIT Bit
The read/write CHARGING_INHIBIT bit is used by the
SMBus Host to inhibit charging or to determine if charging
is inhibited. This bit is also set if the MODE pin is used to
inhibit charging.
Allowed values are:
1b: The LTC1760 will not allow any battery charging
to occur.
0b: The LTC1760 may charge batteries as needed,
(Power On Reset Value).
CHARGER_POR Bit
The read/write CHARGER_POR bit is used to force a char-
ger power on reset.
Writing a 1 to this bit will cause a charger power on reset
with the following effects.
•Charging will be turned off and wake-up charging will
be resumed. This is the same as if the batteries were
removed and then reinserted.
•The three minute wake-up watchdog timer will be
restarted.
Writing a 0 to this bit has no effect. A read of this bit
always returns a 0.
CALIBRATE Bit
The read/write CALIBRATE bit is used either to show the
status of battery calibration cycles in the LTC1760 or to
begin or end a calibration cycle.
CALIBRATE_BAT[4:1] Nibble
The read/write CALIBRATE_BAT[4:1]nibble is used by the
SMBus Host to select the battery to be calibrated or to
determine which individual battery is being calibrated.
Allowed read values are:
0010b: Battery 2 is being calibrated. CALIBRATE must
be 1.
0001b: Battery 1 is being calibrated. CALIBRATE must
be 1.
0000b: No batteries are being calibrated.
Allowed write values are:
0010b: Select Battery 2 for calibration.
0001b: Select Battery 1 for calibration.
0000b: Allow LTC1760 to choose battery to be cali-
brated.
All other values will simply be ignored. This provides a
mechanismto updatethe otherBatterySystemStateCont()
bits without altering this nibble.
2.3.3 BatterySystemInfo() (0×04)
Description:
The SMBus Host uses this function to determine the
capabilities of the LTC1760.
Purpose:
Allows the SMBus Host to determine the number of bat-
teries the LTC1760 supports as well as the specification
revision implemented by the LTC1760.
SMBus Protocol: Read Word
Input/Output: word — Refer to “Section 2.2”for bit map-
ping.
BATTERIES_SUPPORTED Nibble
The read only BATTERIES_SUPPORTED nibble is used
by the SMBus Host to determine how many batteries the
LTC1760 can support. The two-battery LTC1760 always
returns 0011b for this nibble.

LTC1760
20
1760fc
For more information www.linear.com/LTC1760
BATTERY_SYSTEM_REVISION Nibble
The read only BATTERY_SYSTEM_REVISION nibble re-
ports the version of the Smart Battery System Manager
specification supported.
LTC1760 always returns 1000b for this nibble, indicating
Version 1.0 without optional PEC support.
2.3.4 LTC() (0×3C)
Description:
This function returns the LTC version nibble and allows
the user to perform expanded Smart Battery System
Manager functions.
Purpose:
Used by the SMBus Host to determine the version of
the LTC1760 and to program and monitor TURBO and
POWER_OFF special functions.
SMBus Protocol: Read or Write Word.
Input/Output: word —Refer to “Section 2.2”for bit map-
ping.
POWER_OFF Bit
This read/write bit allows the LTC1760 to turn off all
power paths.
Allowed values:
1b: All power paths are off.
0b: Allpower paths areenabled. (poweronreset value).
TURBO Bit
This read/write bit allows the LTC1760 to enter TURBO
charging mode. Refer to “section 3.6”.
Allowed values:
1b: Turbo charging mode enabled.
0b: Turbo charging mode disabled. (Power On Reset
Value).
LTC_Version[3:0] Nibble
Thisread onlynibble alwaysreturns 0001b asthe LTC1760
version.
OPERATION
2.3.5 BatteryMode() (0×03)
Description:
This function is used by the LTC1760 to read the battery’s
Mode register.
Purpose:
Allows the LTC1760 to determine if a battery requires a
conditioning/calibration cycle.
SMBus Protocol: Read Word. LTC1760 reads Battery 1
or Battery 2 as an SMBus Master.
Input/Output: word —Refer to “Section 2.2”for bit map-
ping.
CONDITION_FLAG Bit
The CONDITION_FLAG bit is set whenever the battery
requires calibration.
Allowed values:
1b: Battery requires calibration. (Also known as a
Condition Cycle Request).
0b: Battery does not require calibration.
2.3.6 Voltage() (0×09)
Description:
This function is used by the LTC1760 to read the actual
cell-pack voltage .
Purpose:
Allows the LTC1760 to determine the cell pack voltage
and close the charging voltage servo loop.
SMBus Protocol: Read Word. LTC1760 reads Battery 1
or Battery 2 as an SMBus Master.
Output: unsigned integer —battery terminal voltage in
milli-volts. Refer to “Section 2.2” for bit mapping.
Units: m V.
Range: 0 to 65,535 mV.
Table of contents
Other Linear Technology Batteries Charger manuals

Linear Technology
Linear Technology LTC4075XEDD User manual

Linear Technology
Linear Technology DC1229B User manual

Linear Technology
Linear Technology LTC4020EUHF Quick setup guide

Linear Technology
Linear Technology DC2151A Quick setup guide

Linear Technology
Linear Technology DC1614A Quick setup guide

Linear Technology
Linear Technology DC1484A-A User manual

Linear Technology
Linear Technology DC086 Quick setup guide

Linear Technology
Linear Technology DC763 Series User manual

Linear Technology
Linear Technology LT3651EUHE-4.1 Quick setup guide

Linear Technology
Linear Technology LT3652EDD User manual