LTC1514-3.3/LTC1514-5
APPLICATIONS INFORMATION
resistor divider (see Figure 2). Since the low-battery
comparator is kept alive in shutdown, it may be used to
protect batteries against deep discharge by shutting
down the power supply when the battery voltage gets too
low. The open-drain comparator output allows for flex-
ible interfacing between the LBO output and external
logic. LBO pull-up resistors in the 50k to 1M range are
recommended.
TYPICAL APPLICATIONS
N
3.3V Step-Up/Step-Down Supply with Power Good Output
ON OFF
POWER GOOD
100k LTC1514-3.3
1
SHDN V
OUT
2
LBO
V
IN
3V V
TRIP
3
C1
+
LBI
499k
4
C1
–
GND
1%
806k
1%
Low Power Battery Backup Supply with Autoswitchover and No Reverse Current
MAIN
5V SUPPLY
BACKED-UP
CIRCUITRY
499k
TP0610T
1
1.5M
1%
499k
1%
2
4.6V V
TRIP
3
499k
4
LTC1514-5
SHDN
LBO
LBI
GND
V
OUT
V
IN
C1
+
C1
–
Battery/External Power Autoswitch Regulator
6V
WALL
ADAPTER
INPUT
1M
1%
ON OFF
MBR0520L
LTC1514-5
1
2
3
SHDN
LBO
LBI
GND
V
OUT
V
IN
C1
+
C1
–
8
7
6
5
0.22µF
499k
1%
4
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
W
U
U
U
8
7
6
5
0.22µF
+
10µF
V
IN
2V TO 8V
V
OUT
= 3.3V
±
4%
I
OUT
= 15mA, V
IN
> 2V
I
OUT
= 50mA, V
IN
> 3V
+
10µF
1514 TA05
BAT54
5V BACKUP SUPPLY
I
OUT
= 15mA
TRICKLE CHARGE
AND LTC1514 I
DD
10µF
0.1µF
8
7
6
5
+
+
10µF
1514 TA03
3-CELL
NiCd BATTERY
499k
EXTERNAL
POWER GOOD
+
22µF
3-CELL
NiCd
BATTERY
5V
+
CHARGE PATH
10µF
1514 TA06
7
LINER [ LINEAR TECHNOLOGY ]
