LTC1558-5 Linear Technology, LTC1558-5 Datasheet - Page 6

• Manufacturer Part Number: LTC1558-5
• Description: Backup Battery Controller with Programmable Output
• Manufacturer: Linear Technology

BLOCK
SWITCHING WAVEFORMS
LTC1558-3.3/LTC1558-5
PIN
LOBAT (Pin 9): Low-Battery Detector Output. This is an
open-drain output that pulls low when the backup cell
drops below 1V. It gives early warning to the system
controller that the backup cell is getting weak. This pin is
disabled when the LTC1558 is in trickle charge mode.
6
U
FUNCTIONS
V
MAIN
BATTERY
BAT
Q
U
EXT
DIAGRAM
Simplified LTC1558 Connections in a
U
SHDN
CTL
V
SW
FB
CC
R1
R2
FOR MORE DETAILED APPLICATION SCHEMATICS
PLEASE REFER TO THE TYPICAL APPLICATIONS SECTION
Battery Backup System
U
+
V
REF
1.2V
NiCd
C
+
–
IN
W
V
REF
BACKUP
V
FB
V
MAIN SYSTEM
BAK
IN
REGULATOR
LTC1558
–
+
SW
RESET
V
W
CC
AND DEBOUNCE
LEVEL SENSE
SHUTDOWN
GAS GAUGE
CHARGER
THERMAL
TO
SYSTEM
CONTROL
LOGIC
MULTIPLE
POWER
OUTPUTS
LIMIT
1558 SW01
V
REF
BANDGAP
= 1.272V
RESET (Pin 12): System Reset, Active High. This is a TTL-
compatible output driver. It can be used to connect to
systems that require active high logic. The RESET output
will go high whenever RESET is pulled low. If RESET is
externally pulled low, RESET will go high.
N1
+
–
BACKUP
Cold Power Boot-Up (Main Battery Replaced/Turned On)
GENERATOR
RESET
DETECTOR
V
V
V
RESET
BAT
BAK
UVLO
CC
P1
1
BOOST/BACKUP
V
LOGIC
CC
/V
BAK
2
3
– 6%
RATED BATTERY TERMINAL VOLTAGE
4
1558 BD
200ms
RATED V
V
BACKUP
RESET
RESET
LOBAT
BAK
CC
VOLTAGE
1558 SW02