FEATURES
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LTC1960
Dual Battery Charger/
Selector with SPI Interface
DESCRIPTION
The LTC
®
1960 is a highly integrated battery charger and
selector intended for portable products using dual smart
batteries. A serial SPI interface allows an external microcon-
troller to control and monitor status of both batteries.
A proprietary PowerPath architecture supports simulta-
neous charging or discharging of both batteries. Typical
battery run times are extended by 10%, while charging
times are reduced by up to 50%. The LTC1960 automati-
cally switches between power sources in less than 10µs
to prevent power interruption upon battery or wall adapter
removal.
The synchronous buck battery charger delivers 95% effi-
ciency with only 0.5V dropout voltage, and prevents audible
noise in all operating modes. Patented input current limit-
ing with 5% accuracy charges batteries in the shortest
possible time without overloading the wall adapter.
The LTC1960’s 5mm × 7mm 38-pin QFN and 36-pin nar-
row SSOP packages allow implementation of a complete
SBS-compliant dual battery system while consuming
minimum PCB area.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No R
SENSE
and PowerPath are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
5481178, 5723970, 6304066, 6580258.
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Complete Dual-Battery Charger/Selector System
Serial SPI Interface Allows External µC Control and
Monitoring
Simultaneous Dual-Battery Discharge Extends Run
Time by Typically 10%
Simultaneous Dual-Battery Charging Reduces
Charging Time by Up to 50%
Automatic PowerPath™ Switching in <10µs
Prevents Power Interruption
Circuit Breaker Protects Against Overcurrent Faults
5% Accurate Adapter Current Limit Maximizes
Charging Rate
95% Efficient Synchronous Buck Charger
Charger Has Low 0.5V Dropout Voltage
No Audible Noise Generation, Even with Ceramic
Capacitors
11-Bit VDAC Delivers 0.8% Voltage Accuracy
10-Bit IDAC Delivers 5% Current Accuracy
V
IN
Up to 32V; V
BATT
Up to 28V
Available in 5mm × 7mm 38-Pin QFN and 36-Pin
Narrow SSOP Packages
APPLICATIONS
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Portable Computers
Portable Instruments
TYPICAL APPLICATION
LTC1960 Dual Battery/Selector System Architecture
BATTERY CURRENT (mA)
DC
IN
3500
3000
2500
2000
1500
1000
500
0
3500
3000
2500
2000
1500
1000
500
0
Dual vs Sequential Charging
BAT1
CURRENT
BAT2
CURRENT
SEQUENTIAL
SYSTEM POWER
BAT1
CURRENT
BAT2
CURRENT
DUAL
100
MINUTES
LTC1960
4
BAT2
BAT1
SPI
MICROCONTROLLER
SMBus
0
50
100
150
200
TIME (MINUTES)
250
300
1960 TA01
BATTERY TYPE: 10.8V Li-Ion (MOLTECH NI2020)
REQUESTED CURRENT = 3A
REQUESTED VOLTAGE = 12.3V
MAX CHARGER CURRENT = 4.1A
1960 TA01b
1960fb
1
LTC1960
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Voltage from DCIN, SCP, SCN, CLP, V
PLUS
,
SW to GND................................................. –0.3V to 32V
Voltage from SCH1, SCH2 to GND ............. –0.3V to 28V
Voltage from BOOST to GND ......................–0.3V to 41V
PGND with Respect to GND ...................................±0.3V
CSP, CSN, BAT1, BAT2 to GND ...................... –5V to 28V
LOPWR, DCDIV to GND ............................. –0.3V to 10V
SSB, SCK, MOSI, MISO to GND ................... –0.3V to 7V
COMP1 to GND ............................................ –0.3V to 5V
Operating Ambient Temperature
Range (Note 7) ............................................ 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)
SSOP Only ........................................................ 300°C
PIN CONFIGURATION
TOP VIEW
LOPWR
GDCO
31 SCP
30 SCN
29 BAT1
28 BAT2
27 V
PLUS
39
26 GND
25 SCH2
24 GCH2
23 GCH1
22 SCH1
21 TGATE
20 BOOST
13 14 15 16 17 18 19
DCIN
CLP
COMP1
BGATE
PGND
V
CC
SW
GB2O
GB1O
GDCI
V
PLUS
BAT2
BAT1
SCN
SCP
GDCO
GDCI
GB1O
GB1I
1
2
3
4
5
6
7
8
9
36
SCH2
25
GCH2
34
GCH1
33
SCH1
32
TGATE
31
BOOST
30
SW
29
DCIN
28
V
CC
27
BGATE
26
PGND
25
COMP1
24
CLP
23
CSP
22
CSN
21
MOSI
20
MISO
19
SCK
V
SET
1
I
TH
2
I
SET
3
GND 4
DCDIV 5
SSB 6
SCK 7
MISO 8
MOSI 9
GND 10
CSN 11
CSP 12
TOP VIEW
GB2I
GB1I
38 37 36 35 34 33 32
GB2O
10
GB2I
11
LOPWR
12
V
SET
13
I
TH
14
I
SET
15
GND
16
DCDIV
17
SSB
18
UHF PACKAGE
38-LEAD (5mm
×
7mm) PLASTIC QFN
G PACKAGE
36-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 34°C/W
THE EXPOSED PAD (PIN 39) IS GND. MUST BE SOLDERED TO THE PCB
T
JMAX
= 125°C,
θ
JA
= 70°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1960CG#PBF
LTC1960CUHF#PBF
TAPE AND REEL
LTC1960CG#TRPBF
LTC1960CUHF#TRPBF
PART MARKING*
LTC1960CG
1960
PACKAGE DESCRIPTION
36-Lead Plastic SSOP
38-Lead (5mm × 7mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
0°C to 70°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/
1960fb
2
LTC1960
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
Supply and Reference
DCIN Operating Range
I
CH
DCIN Operating Current
Battery Operating Voltage Range
Battery Drain Current
V
FDC
V
FB1
V
FB2
V
FSCN
UVLO
UVHYS
V
VCC
V
LDR
V
TOL
I
TOL
f
OSC
f
DO
DC
MAX
I
MAX
I
SNS
CMSL
CMSH
V
CL1
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
DCDIV/LOPWR Threshold
DCDIV/LOPWR Hysteresis Voltage
DCDIV/LOPWR Input Bias Current
Short-Circuit Comparator Threshold
Fast PowerPath Turn-Off Threshold
Overvoltage Shutdown Threshold as a Percent
of Programmed Charger Voltage
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
l
l
The
l
denotes the specifications which apply over the full operating
temperature range (Note 7), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, unless otherwise noted.
CONDITIONS
DCIN Selected
Not Charging (DCIN Selected)
Charging (DCIN Selected)
Battery Selected, PowerPath Function (Note 2)
Battery Selected, Not Charging, V
DCIN
= 0V
I
VCC
= 10mA
I
VCC
= 0mA
I
VCC
= 0mA
I
VCC
= 0mA
V
PLUS
Ramping Down, Measured at V
PLUS
to GND
V
PLUS
Rising, Measured at V
PLUS
to GND
5
I
VCC
= 0mA to 10mA
5V ≤ V
OUT
< 25V, (Note 3)
l
l
MIN
6
TYP
MAX
28
UNITS
V
mA
mA
V
µA
V
V
V
V
1
1.3
6
175
0.8
0.7
0.7
0.7
3
3.5
60
5.2
0.2
–0.8
–1
–5
–6
255
300
25
99.5
155
150
0
20
99
1.5
2
28
V
PLUS
Diodes Forward Voltage:
DCIN to V
PLUS
BAT1 to V
PLUS
BAT2 to V
PLUS
SCN to V
PLUS
Undervoltage Lockout Threshold
UV Lockout Hysteresis
V
CC
Regulator Output Voltage
V
CC
Load Regulation
Overall Voltage Accuracy
Overall Current Accuracy
Regulator Switching Frequency
Regulator Switching Frequency in Low
Dropout Mode
Regulator Maximum Duty Cycle
Maximum Current Sense Threshold
CA1 Input Bias Current
CAI Input Common Mode Low
CAI Input Common Mode High
CL1 Turn-On Threshold
TGATE Transition Time:
TGATE Rise Time
TGATE Fall Time
BGATE Transition Time:
BGATE Rise Time
BGATE Fall Time
3.9
V
mV
5.4
1
0.8
1
5
6
345
V
%
%
%
%
%
kHz
kHz
%
Switching Regulator
IDAC Value = 3FF
HEX
V
CSP
, V
CSN
= 12V
Duty Cycle ≥ 99%
l
V
ITH
= 2.2V
V
CSP
= V
CSN
> 5V
140
190
mV
µA
V
V
DCIN
–0.2
95
C
LOAD
= 3300pF 10% to 90%
,
C
LOAD
= 3300pF 10% to 90%
,
C
LOAD
= 3300pF 10% to 90%
,
C
LOAD
= 3300pF 10% to 90%
,
1.166
100
50
50
50
40
1.19
30
20
90
6
100
7
107
200
115
7.9
105
90
90
90
80
1.215
V
mV
ns
ns
ns
ns
V
mV
nA
mV
V
%
1960fb
3
LTC1960
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
DACs
I
RES
t
IP
t
ILOW
V
RES
V
STEP
V
OFF
t
VP
t
ONC
t
ONC
V
CON
V
COFF
V
TOC
V
FC
I
OC(SRC)
I
OC(SNK)
V
CHMIN
t
DLY
t
PPB
t
ONPO
t
OFFPO
V
PONO
IDAC Resolution
IDAC Pulse Period:
Normal Mode
Low Current Mode
VDAC Resolution
VDAC Granularity
VDAC Offset
VDAC Pulse Period
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
V
GCHX
– V
SCHX
> 3V, C
LOAD
= 3nF
V
GCHX
– V
SCHX
< 1V, from Time of V
CSN
<
V
BATX
– 30mV, C
LOAD
= 3nF
I
LOAD
= 1µA
V
GCH1
– V
SCH1
V
GCH2
– V
SCH2
I
LOAD
= 10µA
V
GCH1
– V
SCH1
V
GCH2
– V
SCH2
V
CSN
– V
BATX
, 5V ≤ V
BATX
≤ 28V
V
BATX
– V
CSN
, 5V ≤ V
BATX
≤ 28V
V
GCHX
– V
SCHX
= 1.5V
3.5
250
1
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range (Note 7), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, unless otherwise noted.
CONDITIONS
Guaranteed Monotonic Above I
MAX
/16
MIN
10
6
Guaranteed Monotonic (5V < V
BAT
< 25V)
(Note 6)
7
11
16
0.8
11
5
3
16.5
10
7
10
50
15
TYP
MAX
UNITS
bits
µs
ms
bits
mV
V
µs
ms
µs
Charge MUX Switches
5
5
–0.8
–0.8
5
15
5.8
5.8
–0.4
–0.4
20
35
–2
2
7
7
0
0
40
60
V
V
V
V
mV
mV
µA
µA
BATX Voltage Below Which Charging Is Inhibited (Note 8)
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
V
GS
> –1V, from Time of Battery/DC
Removal, or LOPWR Indication
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 4)
l
l
4.7
V
ms
sec
PowerPath Switches
5
3
10
7
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
60
50
V
V
V
V
V
V
mV
mV
V
POFFO
V
TOP
V
FP
I
OP(SRC)
I
OP(SNK)
5
0
20
25
–4
75
µA
µA
1960fb
4
LTC1960
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
t
ONPI
t
OFFPI
V
PONI
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
SSB/SCK/MOSI Input High/Low Current
SSB/MOSI/SCK Input Low Voltage
SSB/MOSI/SCK Input High Voltage
MISO Output Low Voltage
MISO Output Off-State Leakage Current
Watch Dog Timer
SSB High Time
SCK Period
SCK High Time
SCK Low Time
Enable Lead Time
Enable Lag Time
Input Data Set-Up Time
Input Data Hold Time
Access Time (From Hi-Z to Data Active on MISO)
Disable Time (Hold Time to Hi-Z State on MISO)
Output Data Valid
Output Data Hold
SCK/MOSI/SSB Rise Time
SCK/MOSI/SSB Fall Time
MISO Fall Time
0.8V to 2V
2V to 0.8V
2V to 0.4V, C
L
= 200pF
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range (Note 7), otherwise specifications are at T
A
= 25°C. V
DCIN
= 20V, V
BAT1
= 12V, V
BAT2
= 12V, unless otherwise noted.
CONDITIONS
V
GS
< –3V, C
LOAD
= 3nF (Note 5)
V
GS
> –1V, C
LOAD
= 3nF (Note 5)
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
l
l
l
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
1
0.8
V
V
V
V
V
V
µA
V
V
V
µA
sec
ns
µs
ns
ns
ns
ns
ns
ns
V
POFFI
Logic I/O
I
IH
/I
IL
V
IL
V
IH
V
OL
I
OFF
T
WD
t
SSH
t
CYC
t
SH
t
SL
t
LD
t
LG
t
su
t
H
t
A
t
dis
t
V
t
HO
t
Ir
t
If
t
Of
–1
2
0.4
2
1.2
680
C
LOAD
= 200pF R
PULLUP
= 4.7k on MISO
l
I
OL
= 1.3mA
V
MISO
= 5V
l
l
SPI Timing (See Timing Diagram)
l
2.5
4.5
2
680
680
200
200
100
100
125
125
580
0
250
250
400
ns
ns
ns
ns
ns
ns
ns
C
L
= 200pF R
PULLUP
= 4.7k on MISO
,
l
l
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.
Note 3.
See Test Circuit.
Note 4.
DCIN, BAT1, BAT2 are held at 12V and GDCI, GB1I, GB2I are
forced to 10.5V. SCP is set at 12.0V 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 5.
Extrapolated from testing with C
L
= 50pF
.
Note 6.
VDAC offset is equal to the reference voltage, since
V
OUT
= V
REF
(16mV • VDAC
(VALUE)
/2047 + 1)
Note 7.
The LTC1960C is guaranteed to meet specified performance from
0°C to 70°C and is designed, characterized and expected to meet specified
performance at –40°C and 85°C, but is not tested at these extended
temperature limits.
Note 8.
Does not apply to low current mode. Refer to “The Current DAC
Block” in the Operation section.
1960fb
5
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