Datasheet
LTC1998
12
1998fb
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2001
LT 0809 REV B • PRINTED IN USA
1998 TA05
LTC1998
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
4
3
2
1
5
6
GND
R1
787k
1%
R2
68.1k
1%
R3
147k
1%
+
Si2301
CRITICAL
CIRCUITRY
NONCRITICAL
CIRCUITRY
LOW THRESHOLD = 2.7V
HYSTERESIS = 100mV
Li-Ion
REGULATOR
4
3
2
1
5
6
R4
909k
1%
R5
6.98k
1%
R6
76.8k
1%
LTC1998
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
GND
4
3
2
1
5
6
R1
619k
1%
R2
6.04k
1%
R3
383k
1%
LTC1998
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
GND
V
IN
NC
V
+
R7
1M
2N7002
WINDOW LOW THRESHOLD = 2.6V
HYSTERESIS = 10mV
WINDOW HIGH THRESHOLD = 3.1V
HYSTERESIS = 10mV
1998 TA06
V
OUT
V
OUT
= V
+
WHEN
2.6V ≤ V
IN
≤ 3.1V
1998 TA03
4
3
2
1
5
6
3.3V
R1
715k
1%
R2
9.09k
1%
R3
274k
1%
OUT
LTC1998
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
GND
LOW THRESHOLD = 2.9V
HYSTERESIS = 15mV
1998 TA04
4
3
2
1
5
6
R1
787k
1%
R4
1M
R2
68.1k
1%
R3
147k
1%
+
+
3V
BACKUP
BATTERY
2.5V TO 4.2V
BAT54C
BAT54C
Si2301
Si2301
LTC1998
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
GND
V
OUT
SWITCHES TO BACKUP BATTERY WHEN PRIMARY FALLS BELOW 2.7V.
SWITCHES BACK TO PRIMARY WHEN VOLTAGE RECOVERS TO ≥ 2.8V
Li-Ion
MBRM120
1998 TA01
LTC1998
R1
1%
R2
1%
R3
1%
V
H.A
V
TH.A
BATT
V
LOGIC
BATTLO
4
3
2
1
5
6
μP
Li-Ion
GND
0.1μF
V
BATT
=
1.5V TO 4.2V
V
LOGIC
=
1V TO 5V
+
REGULATOR
RELATED PARTS
TYPICAL APPLICATIONS
PART NUMBER DESCRIPTION COMMENTS
LTC1440/LTC1540 Micropower Comparator with 1% Reference 1.182V ±1% Reference, ±10mV (Max) Input Offset
LTC1441/LTC1442 Micropower Dual Comparator with 1% Reference 1.182V ±1% Reference (LTC1442)
LTC1443/LTC1444/LTC1445 Micropower Quad Comparator with 1% Reference LTC1443 has 1.182V Reference, LTC1444/LTC1445 have 1.221V
Reference and Adjustable Hysteresis
Micropower 2.9V V
CC
Threshold
Detector with 15mV Hysteresis
Low Battery Load Reduction Circuit
Backup Battery Switchover Circuit
High Accuracy Window Comparator
with Dual Hysteresis
Single Li-Ion Cell Low Battery Detector