LTC1479
PowerPath Controller
for Dual Battery Systems
FEATURES
s
s
DESCRIPTION
The LTC
®
1479 is the “heart” of a total power management
solution for single and dual battery notebook computers
and other portable equipment. The LTC1479 directs power
from up to two battery packs and a DC power source to the
input of the main system switching regulator. It works in
concert with related LTC power management products
(e.g. LTC1435, LT
®
1511, etc.) to create a total system
solution; starting from the batteries and the DC power
source, and ending at the input of each of the computer’s
complex loads. A system-provided power management
µP
monitors and actively directs the LTC1479.
The LTC1479 uses low loss N-channel MOSFET switches
to direct power from three main sources. An adaptive
current limiting scheme reduces capacitor and battery
inrush current by controlling the gates of the MOSFET
switches during transitions. The LTC1479 interfaces di-
rectly to the LT1510, LT1511 and LT1620/LTC1435 bat-
tery charging circuits.
, LTC and LT are registered trademarks of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation.
s
s
s
s
s
s
Complete Power Path Management for Two
Batteries, DC Power Source, Charger and Backup
Compatible with Li-Ion, NiCd, NiMH and Lead-Acid
Battery Chemistries
“3-Diode” Mode Ensures Powers is Available
under “Cold Start” Conditions
All N-Channel Switching Reduces Power Losses
Capacitor and Battery Inrush Current Limited
“Seamless” Switching Between Power Sources
Independent Charging and Monitoring of Two
Battery Packs
New, Small Footprint, 36-Lead SSOP Package
APPLICATIONS
s
s
s
s
s
Notebook Computer Power Management
Portable Instruments
Handheld Terminals
Portable Medical Equipment
Portable Industrial Control Equipment
TYPICAL APPLICATION
Dual Battery PowerPath
TM
Controller System Block Diagram
DCIN
SW A/B
SW C/D
SW E/F
SW G
BAT2
BATTERY CHARGER
(LT1510/LT1511/
LT1620/LTC1435)
BACKUP
REGULATOR
(LT1304)
POWER
MANAGEMENT
µP
SW H
HIGH EFFICIENCY
DC/DC SWITCHING
REGULATOR
(LTC1435/LTC1438
ETC.)
AC
ADAPTER
R
SENSE
BAT1
LTC1479
PowerPath CONTROLLER
STATUS &
CONTROL
U
U
U
+
C
IN
5V
1479 TA01
1
LTC1479
ABSOLUTE
MAXIMUM
RATINGS
DCIN, BAT1, BAT2 Supply Voltages .......... – 0.3V to 32V
SENSE
+
, SENSE
–
, V
BAT
, V
+
..................... – 0.3V to 32V
GA, GB, GC, GD, GE, GF, GG, GH .............. – 0.3V to 42V
SAB, SCD, SEF, SG, SH ............................ – 0.3V to 32V
SW, V
GG
................................................... – 0.3V to 42V
DCDIV, BDIV ............................................ – 0.3V to 5.5V
All Logic Inputs (Note 1).......................... – 0.3V to 7.5V
All Logic Outputs (Note 1) ....................... – 0.3V to 7.5V
V
CC
Regulator Output Current ................................ 1mA
V
CCP
Regulator Output Current .............................. 1mA
V
+
Output Current .................................................. 1mA
V
GG
Regulator Output Current ............................ 100µA
Operating Temperature
LTC1479CG ............................................. 0°C to 70°C
LTC1479IG ........................................ – 40°C to 85°C
Junction Temperature........................................... 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
PACKAGE/ORDER INFORMATION
TOP VIEW
DCIN
DCDIV
LOBAT
GA
SAB
GB
GC
SCD
GD
1
2
3
4
5
6
7
8
9
36 V
BKUP
35 BAT1
34 BAT2
33 BDIV
32 V
BAT
31 CHGMON
30 BATSEL
29 GG
28 SG
27 GH
26 SH
25 DCINGOOD
24 DCIN/BAT
23 BATDIS
22 3DM
21 CHGSEL
20 V
CCP
19 GND
ORDER PART
NUMBER
LTC1479CG
LTC1479IG
GE 10
SEF 11
GF 12
SENSE
+
13
SENSE
–
14
V
CC
15
V
GG
16
V
+
17
SW 18
G PACKAGE (209 mils)
36-LEAD PLASTIC SSOP
T
JMAX
= 100°C,
θ
JA
= 95°C/ W
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
V
DCIN
= 25V, V
BAT1
= 16V, V
BAT2
= 12V, T
A
= 25°C unless otherwise noted. (Note 2)
SYMBOL
V
DCIN
V
BAT1
V
BAT2
V
BKUP
I
DCIN
I
VBAT1
I
VBAT2
I
VBKUP
V
CCP
V
CC
V
GG
V
UVLO
V
UVLOHYS
PARAMETER
DCIN Operating Range
Battery 1 Operating Range
Battery 2 Operating Range
Backup Operating Range
DCIN Operating Current
Battery 1 Operating Current
Battery 2 Operating Current
Backup Operating Current
V
CCP
Regulator Output Voltage
V
CC
Regulator Output Voltage
V
GG
Gate Supply Voltage
UV Lockout Threshold
UV Lockout Hysteresis
CONDITIONS
(Mode 1) DCIN Selected
(Mode 5) Battery 1 Selected
(Mode 6) Battery 2 Selected
(Mode 8) Backup Operation
(Mode 1) DCIN Selected
(Mode 5) Battery 1 Selected
(Mode 6) Battery 2 Selected
(Mode 8) Backup Operation (V
BKUP
= 6V)
(Modes 1, 5, 6) DCIN, Battery 1 or Battery 2 Selected
(Modes 1, 5, 6) DCIN, Battery 1 or Battery 2 Selected
(Modes 1, 5, 6) DCIN, Battery 1 or Battery 2 Selected
(Mode 9) No Power, V
BATX
Falling from 12V
(Mode 9) No Power, V
BATX
Rising from 1V
q
q
q
MIN
6
6
6
6
TYP
MAX
28
28
28
28
UNITS
V
V
V
V
µA
µA
µA
µA
V
V
V
V
V
Power Supplies
175
150
150
40
4.0
3.3
34.0
4.0
0.2
4.8
3.6
36.3
4.5
0.5
500
500
500
100
6.0
3.9
40.0
5.0
1.0
2
U
W
U
U
W W
W
LTC1479
DC ELECTRICAL CHARACTERISTICS
V
DCIN
= 25V, V
BAT1
= 16V, V
BAT2
= 12V, T
A
= 25°C unless otherwise noted. (Note 2)
SYMBOL
V
THDCDIV
PARAMETER
DCDIV Threshold Voltage
CONDITIONS
(Mode 1) V
DCDIV
Rising from 1V to 1.5V
(Mode 1) V
DCDIV
Falling from 1.5V to 1V
(Mode 1) V
DCDIV
= 1.5V
(Mode 1) V
DCDIV
= 1V, I
DCINGOOD
= 100µA
(Mode 1) V
DCDIV
= 1.5V, V
DCINGOOD
= 0V
(Mode 1) V
DCDIV
= 1.5V, V
DCINGOOD
= 7V
(Modes 5, 6) V
BDIV
Falling from 1.5V to 1V
(Modes 5, 6) V
BDIV
Rising from 1V to 1.5V
(Modes 5, 6) V
BDIV
= 1.5V
(Modes 5, 6) V
BDIV
= 1V, I
LOBAT
= 100µA
(Modes 5, 6) V
BDIV
= 1.5V, V
LOBAT
= 7V
(Modes 5, 6) Each Switch Tested Independently
(Modes 5, 6) Each Switch Tested Independently
5.0
4.5
5
5
q
q
q
MIN
1.190
10
0
1
TYP
1.215
35
20
0.1
2
MAX
1.240
50
0.4
6
±1
UNITS
V
mV
nA
V
µA
µA
V
mV
nA
V
µA
Ω
µA
V
V
V
µA
µA
V
µA
µA
µA
mA
mA
DCIN Good Monitor
V
HYSDCDIV
DCDIV Hysteresis Voltage
I
BIASDCDIV
DCDIV Input Bias Current
V
LODCGD
I
PUDCGD
I
LKGDCGD
V
THLOBAT
I
BIASBDIV
V
LOLOBAT
I
LKGLOBAT
DCINGOOD Output Low Voltage
DCINGOOD Pull-Up Current
DCINGOOD Leakage Current
Low-Battery Threshold Voltage
BDIV Input Bias Current
LOBAT Output Low Voltage
LOBAT Output Leakage Current
Battery Monitor
1.190
10
0
200
1.215
35
20
0.1
400
0.4
±1
800
±1
5.5
5.2
0
15
15
0.20
100
100
100
3
3
50
150
250
±1
q
q
1.240
50
V
HYSLOBAT
Low-Battery Hysteresis Voltage
R
ONBATSW
Battery Switch ON Resistance
I
LKGBATSW
Battery Switch OFF Leakage
Gate Drivers
V
GS(ON)
V
GS(OFF)
I
BSENSE
+
I
BSENSE
–
V
SENSE
I
PDSAB
I
PDSCD
I
PDSEF
I
PDSG
I
PDSH
R
ONCMON
I
LKGCMON
V
HIDIGIN
V
LODIGIN
I
HIDIGIN
I
LODIGIN
I
PUDIGIN
Gate-to-Source ON Voltage (GA to GF) (Modes 1, 2, 4, 5, 6) I
GS
= –1µA
Gate-to-Source ON Voltage (GG, GH) (Modes 2, 4) I
GS
= –1µA
Gate-to-Source OFF Voltage
SENSE
+
Input Bias Current
SENSE
–
Input Bias Current
Inrush Current Limit Sense Voltage
SAB Pull-Down Current
SCD Pull-Down Current
SEF Pull-Down Current
SG Pull-Down Current
SH Pull-Down Current
CHGMON Switch ON Resistance
CHGMON Switch OFF Leakage
Input High Voltage
Input Low Voltage
Input Leakage Current
Input Leakage Current
Input Pull-Up Current
(Modes 1, 2, 4, 5, 6) I
GS
= 100µA
(Modes 1, 5, 6)
(Modes 1, 5, 6)
(Modes 1, 5, 6)
(Modes 5, 6) V
SAB
= 10V
(Mode 1) V
SCD
= 10V
(Mode 1) V
SEF
= 10V
(Mode 1) V
SG
= 10V
(Mode 1) V
SH
= 10V
(Modes 5, 6) Each Switch Tested Independently
(Modes 5, 6) Each Switch Tested Independently
(Mode 1) All Digital Inputs
(Mode 1) All Digital Inputs
(Mode 1) All Digital Inputs, V
DIGINX
= 7V
(Mode 1) V
DIGINX
= 0V (Note 3)
(Mode 1) V
DIGINX
= 0V (Note 4)
7.0
7.0
0.4
30
30
0.25
300
300
300
0.15
30
30
30
Charge Monitor
Ω
µA
V
0.8
±1
±1
1
2
6
V
µA
µA
µA
Digital Inputs
2
3
LTC1479
AC ELECTRICAL CHARACTERISTICS
V
DCIN
= 25V, V
BAT1
= 16V, V
BAT2
= 12V, T
A
= 25°C unless otherwise noted. (Note 2)
SYMBOL
t
ONGA/GB
t
ONGC/GD
t
ONGE/GF
t
OFFGA/GB
t
OFFGC/GD
t
OFFGE/GF
t
ONGG/GH
t
OFFGG/GH
f
OVGG
t
dLOBAT
t
dDCINGOOD
PARAMETER
Gate A/B Turn-On Time
Gate C/D Turn-On Time
Gate E/F Turn-On Time
Gate A/B Turn-Off Time
Gate C/D Turn-Off Time
Gate E/F Turn-Off Time
Gate G/H Turn-On Time
Gate G/H Turn-Off Time
V
GG
Reg Operating Frequency
LOBAT Delay Times
DCINGOOD Delay Times
CONDITIONS
V
GS
> 3V (Note 5)
V
GS
> 3V (Note 5)
V
GS
> 3V (Note 5)
V
GS
< 1V (Note 5)
V
GS
< 1V (Note 5)
V
GS
< 1V (Note 5)
V
GS
> 3V (Note 5)
V
GS
< 1V (Note 5)
∆V
BDIV
=
±100mV,
R
PULLUP
= 51k
∆V
DCDIV
=
±100mV,
R
PULLUP
= 51k
MIN
TYP
30
30
30
3
3
3
300
5
30
5
5
MAX
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
kHz
µs
µs
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
The logic inputs are high impedance CMOS gates with ESD
protection diodes to ground and therefore should not be forced below
ground. These inputs can however be driven above the V
CCP
or V
CC
supply
rails as there are no clamping diodes connected between the input pins
and the supply rails. This facilitates operation in mixed 5V/3V systems.
Note 2:
The Selected Operating Mode Truth Table, which defines the
operating conditions and logical states associated with each “normal”
operating mode, should be used in conjunction with the Electrical
Characteristics table to establish test conditions. Actual production test
conditions may be more stringent.
Note 3:
The following inputs are high impedance CMOS inputs:
3DM and DCIN/BAT and have no internal pull-up current.
Note 4:
The following inputs have built-in 2µA pull-up current sources
(passed through series diodes): BATSEL, BATDIS and CHGSEL.
Note 5:
Gate turn-on and turn-off times are measured with no inrush
current limiting, i. e., V
SENSE
= 0V, using Si4936DY MOSFETs in the typical
application circuit.
TRUTH TABLE
SELECTED MODES
(Selected Operating Modes)
LOGIC INPUTS
SW
A/B
On
On
SWITCH STATUS
SW SW SW
C/D E/F
G
Off Off Off
Off Off On
Off
Off
Off
On
Off
Off
Off
Off
Off
Off
Off
Off
Off
Off
OUTPUTS
SW
H
Off
Off
Off
On
Off
Off
Off
Off
Off
Off
Off
CHGMON
Hi-Z
BAT1
Hi-Z
BAT2
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
V
BAT
LOBAT
BAT1
H
BAT1
H
BAT2
BAT2
BAT1
BAT2
BAT1
BAT1
BAT2
BAT1
BAT1
H
H
H
H
L
L
L
L
L
DCINGOOD
H
H
H
H
L
L
L
L
L
H
H
NO. MODE
3DM DCIN/BAT BATSEL BATDIS CHGSEL
1 DC Operation
H
H
H
L
H
2 DC Operation and
H
H
H
H
H
BAT1 Charging
3 DC Operation and
H
H
L
L
L
On
Off
BAT2 Disconnected
4 DC Operation and
H
H
L
H
L
On
Off
BAT2 Charging
5 BAT1 Operation
H
L
H
H
H
Off
On
6 BAT2 Operation
H
L
L
H
H
Off
Off
7 BAT1 Low and
H
L
H
L
H
Off
Off
Disconnected
8 Backup Operation
H
L
H
L
H
Off
Off
9 No Power
L
L
L
L
L
Off
Off
(No Backup)
10 DC Reconnected
L
L
H
L
H
3DM* 3DM*
11 DC Connected
H
H
H
L
H
On
Off
and Reset
*
3DM = Three Diode Mode. When this mode is invoked, only the first
MOSFET switch in each back-to-back switch pair, i. e., SW A, SW C and
SW E is turned on. Current may still pass through the inherent body
diode of the idled switches, i.e., SW B, SW D and SW F to help restart
3DM* Off
Off Off
the system after abnormal operating conditions have been encountered.
See the Timing Diagram and Applications Information sections for
further details.
4
LTC1479
TYPICAL PERFORMANCE CHARACTERISTICS
DCIN Supply Current
350
300
DCIN SUPPLY CURRENT (µA)
BAT1 SUPPLY CURRENT (µA)
250
200
150
100
50
0
0
5
20
30
15
25
10
DCIN SUPPLY VOLTAGE (V)
35
250
200
150
100
50
0
0
5
20
30
15
25
10
BAT1 SUPPLY VOLTAGE (V)
35
BAT2 SUPPLY CURRENT (µA)
MODE 1, DCDIV = 1.5V
NO OTHER POWER
T
J
= 25°C
V
BKUP
Supply Current
70
60
50
40
30
20
10
0
0
5
20
30
15
25
V
BKUP
SUPPLY VOLTAGE (V)
10
35
MODE 8
NO OTHER POWER
T
J
= 25°C
V
BKUP
SUPPLY CURRENT (µA)
V
GG
SUPPLY VOLTAGE (V)
V
CC
Supply Voltage
4.0
3.9
V
CC
SUPPLY VOLTAGE (V)
MODE 1
V
DCIN
= 24V
3.8
3.7
3.6
3.5
3.4
3.3
50
100
25
75
– 50 – 25
0
JUNCTION TEMPERATURE (°C)
V
CCP
SUPPLY VOLTAGE (V)
U W
1479 G01
BAT1 Supply Current
350
300
MODE 5
NO OTHER POWER
T
J
= 25°C
350
300
250
200
150
100
50
0
BAT2 Supply Current
MODE 6
NO OTHER POWER
T
J
= 25°C
0
5
20
30
15
25
10
BAT2 SUPPLY VOLTAGE (V)
35
1479 G02
1479 G03
V
GG
Supply Voltage
44
42
40
38
36
34
32
30
50
100
25
75
– 50 – 25
0
JUNCTION TEMPERATURE (°C)
MODE 1
V
DCIN
= 24V
125
1479 G04
1479 G05
V
CCP
Supply Voltage
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
50
100
25
75
– 50 – 25
0
JUNCTION TEMPERATURE (°C)
MODE 1
V
DCIN
= 24V
125
125
1479 G06
1479 G07
5
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