LTC1998

12

1998fa

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

© LINEAR TECHNOLOGY CORPORATION 2001

LT 0108 REV A • PRINTED IN USA

1998 TA05

LTC1998

BATT

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

REGULATOR

4

3

2

1

5

6

R4

909k

1%

R5

6.98k

1%

R6

76.8k

1%

LTC1998

BATT

BATTLO

GND

4

3

2

1

5

6

R1

619k

1%

R2

6.04k

1%

R3

383k

1%

LTC1998

BATT

BATTLO

GND

NC

R7

1M

2N7002

WINDOW LOW THRESHOLD = 2.6V

HYSTERESIS = 10mV

WINDOW HIGH THRESHOLD = 3.1V

HYSTERESIS = 10mV

1998 TA06

1998 TA03

4

3

2

1

5

6

3.3V

R1

715k

1%

R2

9.09k

1%

R3

274k

1%

OUT

LTC1998

BATT

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

BATT

BATTLO

GND

SWITCHES TO BACKUP BATTERY WHEN PRIMARY FALLS BELOW 2.7V.

SWITCHES BACK TO PRIMARY WHEN VOLTAGE RECOVERS TO ≥ 2.8V

MBRM120

1998 TA01

LTC1998

R1

1%

R2

1%

R3

1%

BATT

BATTLO

4

3

2

1

5

6

μP

GND

0.1μF

1.5V TO 4.2V

1V TO 5V

+

REGULATOR

RELATED PARTS

TYPICAL APPLICATIONS

PART NUMBER

DESCRIPTION

COMMENTS

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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

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