LT1512
14
1512fc
For more information www.linear.com/LT1512
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
LINEAR TECHNOLOGY CORPORATION 2008
LT 0315 REV C • PRINTED IN USA
relaTeD parTs
Typical applicaTion
PART NUMBER DESCRIPTION COMMENTS
LT1239 Backup Battery Management System Charges Backup Battery and Regulates Backup Battery Output when
Main Battery Removed
LT C
®
1325 Microprocessor Controlled Battery Management System Can Charge, Discharge and Gas Gauge NiCd, NiMH and Pb-Acid Batteries
with Software Charging Profiles
LT1510 1.5A Constant-Current/Constant-V
oltage Battery Charger Step-Down Charger for Li-Ion, NiCd and NiMH
LT1511 3.0A Constant-Current/Constant-Voltage Battery Charger
with Input Current Limiting
Step-Down Charger that Allows Charging During Computer Operation and
Prevents
Wall-Adapter Overload
LT1513 SEPIC Constant-Current/Constant-Voltage Battery Charger Step-Up/Step-Down Charger for Up to 2A Current
LTC4020 55V Buck-Boost Multi-Chemistry Battery Charger 4.5V to 55V input, up to 20+A charge current, up to 55V output/charge
voltage, Li-Ion and SLA battery termination algorithms on board
The circuit in Figure 6 will provide adapter current limit-
ing to ensure that the battery charger never overloads
the adapter. In addition, it adjusts charging current to a
lower
value if other system power increases to the point
where the adapter would be overloaded. This allows the
LT1512 to charge the battery at the maximum possible
rate without concern about varying system power levels.
The LM301 op amp used here is unusual in that it can
operate with its inputs at a voltage equal to the positive
supply voltage.
Figure 6. Adding Adapter Current Limiting
LT1512
I
FB
V
C
V
IN
L1 A*
L1 B*
0.5A
1
1
3
2
2
3
8
8
5
•
•
4
4
6
7
7
6
TO FB PIN
D2
1N4148
GND
GND S
FB
1512 F06
V
SW
SYNC
AND/OR
SHUTDOWN
WALL
ADAPTER
INPUT
S/S
C3
22µF
25V
SYSTEM
POWER
C2**
2.2µF
C5
0.1µF
R5
1k
R7
12k
Q1
2N3904
*
**
L1 A, L1 B ARE TWO 33µH WINDINGS ON A
COMMON CORE: COILTRONICS CTX33-3
TOKIN CERAMIC 1E225ZY5U-C203-F
C4
0.22µF
R4
24Ω
+
R1
R2
R3
0.2Ω
C1
22µF
25V
+
D1
MBRS130LT3
R6
0.2Ω
+
–
30pF
LM301
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com/LT1512
