12

LT1490/LT1491

14901fa LT/TP 0897 4K REV A • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 1996

PART NUMBER

DESCRIPTION

COMMENTS

LT1078/LT1079

Dual/Quad 55

µA Max, Single Supply, Precision Op Amps

Input/Output Common Mode Includes Ground, 70

and 2.5

µV/°C Drift (Max), 200kHz GBW, 0.07V/µs Slew Rate

LTC1152

Rail-to-Rail Input, Rail-to-Rail Output, Zero-Drift Amplifier

High DC Accuracy, 10

1V/

µs Slew Rate, Supply Current 2.2mA (Max), Single Supply,

Can Be Configured for C-Load

LT1178/LT1179

Dual/Quad 17

µA Max, Single Supply, Precison Op Amps

Input/Output Common Mode Includes Ground, 70

and 4

µV/°C Drift (Max), 85kHz GBW, 0.04V/µs Slew Rate

LT1366/LT1367

Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps

475

C-Load is a trademark of Linear Technology Corporation.

Ring-Tone Generator

RELATED PARTS

–

+

–

+

–

+

–

+

1490/1491 TA03

R6

10k

R2

47k

R7

16k

R8

620k

R4

1.6M

R1

33k

R3

10k

R5

100k

R10

620k

C4

0.068

µF

9

10

6

7

8

1

5

C3

0.047

µF

C5

0.01

µF

R13

130k

R12

10k

R15

47k

R14

10k

R24

420

C7

47

µF

LOAD

UP TO

TEN

PHONES

R23

4.7k

R26

2k

Q5

2N3904

Q4

2N3906

Q2

IRF9620

–180V

POWER AMPLIFIER

SMOOTHING FILTER

20Hz OSCILLATOR

CADENCE OSCILLATOR

*LED OF OPTO1 ILLUMINATES WHEN THE PHONE IS OFF THE HOOK

OFF HOOK DETECTION

R18

100

Ω

R17

620

Ω

R16

100k

Z1

15V

100k

R25

4.7k

C6

0.033

µF

R21

150

Ω

R19

620

Ω

Z2

15V

R9

300k

R11

10k

D1

1N4148

C2

0.47

µF

C1

1

µF

2

3

1/4 LT1491

1/4 LT1491

12

4

11

13

Q1

IRF628

Q3

2N3904

60V

14

1/4 LT1491

1/4 LT1491

OPTO1*

R20

100k

Linear Technology Corporation