LTC1479_15 Datasheet, PDF (16/24 Pages) Linear Technology – PowerPath Controller for Dual Battery Systems

LTC1479
APPLICATIONS INFORMATION
DCIN
Li-ION
BATTERY
PACK #1
330Ω
SW A SW B
R_SENSE
0.033Ω
SW C SW D
0.1µF
SW E SW F
R_DC2
R_DC1
DCIN
DCDIV
GA SAB GB
GC SCD GD
GE SEF GF SENSE ⁺ SENSE ^–
V_BKUP
LTC1538-AUX
TRIPLE, HIGH EFFICIENCY,
SWITCHING REGULATOR
12V AUX
5V
3.3V
BACKUP
NiCD
BACKUP
REGULATOR
Li-ION
BATTERY
PACK #2
BAT1
BAT2
V_BAT
R_B2
BDIV
R_B1
LTC1479
V_CC
V_CCP
+
2.2µF
16V
+
0.1µF
V⁺
+
1µF
50V
1mH*
SW V_GG
+
1µF
50V
GG SG
*COILCRAFT 1812LS-105 XKBC [phone]
SW G
2
5
CHGMON
GH SH
SW H
POWER
MANAGEMENT
µP
DCIN
LT1510
Li-ION BATTERY
CHARGER
1479 F08
Figure 8. Simplified Dual Li-Ion Battery Power Management System
FROM
PowerPath
CONTROLLER
5V_CC
FROM
DC/DC
BACKUP
Q1
2N7002
D2
BAS16LT1
R2
470k
(BOLD LINES INDICATE HIGH CURRENT PATHS)
ROHM
DTA144E ^R1
10k
L1*
10µH
D1
MBR0530
TO INPUT
OF DC/DC
CONVERTER
NiCD ⁺
CELL
C1
0.1µF
C2
0.1µF
4
SW
2
LBO
8
FB
LT1304
1
LBI
7
SHDN
3
I_LIM GND V_IN
6
5
R3
22k
R4
390k
1%
R5
100k
1%
5V_CC
FROM
DC/DC
C3
0.1µF
1479 F09
Figure 9. LT1304 Micropower Backup Converter Circuit
cropower DC/DC converter. As shown in Figure 9, the
LT1304 monitors the input supply voltage and activates
when it drops below 6V.
Power for the DCIN and battery monitors and the logic
supply in the LTC1479 is then obtained from the output of
the LT1304 step-up regulator.
Charger System Interface
The LTC1479 is designed to work directly with constant-
voltage (CV), constant-current (CC) battery chargers such
as the LT1510 and LT1511.
LT1510 Battery Charger Interface
As illustrated in Figure 10, the LT1510 CV/CC battery
charger, takes power from the DC adapter input through
Schottky diode D1. The output of the charger is directed to
16