LT1512 Linear Technology, LT1512 Datasheet - Page 12

• Manufacturer Part Number: LT1512
• Description: SEPIC Constant-Current/ Constant-Voltage Battery Charger
• Manufacturer: Linear Technology

RELATED PARTS
PART NUMBER DESCRIPTION
LT1239
LTC
LT1510
LT1511
LT1513
LT1512
The circuit in Figure 6 will provide adapter current limiting
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
12
TYPICAL
®
1325
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone]
Backup Battery Management System
Microprocessor Controlled Battery Management System
1.5A Constant-Current/Constant-Voltage Battery Charger
3.0A Constant-Current/Constant-Voltage Battery Charger
with Input Current Limiting
SEPIC Constant-Current/Constant-Voltage Battery Charger Step-Up/Step-Down Charger for Up to 2A Current
ADAPTER
APPLICATION
INPUT
WALL
**
*
L1 A, L1 B ARE TWO 33 H WINDINGS ON A
COMMON CORE: COILTRONICS CTX33-3
TOKIN CERAMIC 1E225ZY5U-C203-F
FAX
: [phone]
R5
1k
R7
12k
Q1
2N3904
7
0.2
4
R6
–
2
LM301
U
TELEX
6
1N4148
+
: 499-3977
8
3
D2
Figure 6. Adding Adapter Current Limiting
1
30pF
TO FB PIN
SHUTDOWN
+
AND/OR
SYNC
C3
22 F
25V
SYSTEM
POWER
4
GND GND S
S/S
COMMENTS
Charges Backup Battery and Regulates Backup Battery Output when
Main Battery Removed
Can Charge, Discharge and Gas Gauge NiCd, NiMH and Pb-Acid Batteries
with Software Charging Profiles
Step-Down Charger for Li-Ion, NiCd and NiMH
Step-Down Charger that Allows Charging During Computer Operation and
Prevents Wall-Adapter Overload
7
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.
6
LT1512
V
V
IN
C
5
1
C5
0.1 F
•
V
I
L1 A*
FB
SW
FB
3
C4
0.22 F
8
2
24
R4
2.2 F
C2**
MBRS130LT3
•
R3
0.2
L1 B*
D1
LINEAR TECHNOLOGY CORPORATION 1996
R1
R2
LT/GP 1096 7K • PRINTED IN THE USA
0.5A
+
1512 F06
C1
22 F
25V