LT1490/LT1491
U
TYPICAL APPLICATION
Ring-Tone Generator
60V
R16
100k
R2
47k
Q1
R3
R5
IRF628
R6
Q3
2N3904
10k
100k
10k
C3
C2
0.047µF
0.47µF
R17
620Ω
Z1
15V
100k
5
R9
300k
R11
+
10k
10
9
3
2
7
D1
1N4148
1/4 LT1491
+
+
1
6
8
R1
33k
1/4 LT1491
1/4 LT1491
–
4
13
12
R7
16k
–
C4
0.068µF
–
–
14
C7
R18
1/4 LT1491
100Ω
+
R26
2k
R24
420
R23
4.7k
R12
10k
R14
10k
R4
R8
620k
C1
1µF
11
47µF
R10
620k
1.6M
SMOOTHING FILTER
OPTO1*
R25
4.7k
R13
130k
R15
47k
C5
0.01µF
CADENCE OSCILLATOR
20Hz OSCILLATOR
Q5
2N3904
UP TO
LOAD TEN
PHONES
Z2
15V
R19
620Ω
Q4
2N3906
Q2
IRF9620
R21
150Ω
*LED OF OPTO1 ILLUMINATES WHEN THE PHONE IS OFF THE HOOK
OFF HOOK DETECTION
C6
0.033µF
POWER AMPLIFIER
R20
100k
–180V
1490/1491 TA03
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
Input/Output Common Mode Includes Ground, 70µV V
LT1078/LT1079
Dual/Quad 55µA Max, Single Supply, Precision Op Amps
OS(MAX)
and 2.5µV/°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, 10µV V , 100nV/°C, 1MHz GBW,
OS(MAX)
1V/µs Slew Rate, Supply Current 2.2mA (Max), Single Supply,
Can Be Configured for C-LoadTM Operation
LT1178/LT1179
LT1366/LT1367
Dual/Quad 17µA Max, Single Supply, Precison Op Amps
Input/Output Common Mode Includes Ground, 70µV V
OS(MAX)
and 4µV/°C Drift (Max), 85kHz GBW, 0.04V/µs Slew Rate
Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps
475µV V , 500V/mV A , 400kHz GBW
OS(MAX)
VOL(MIN)
C-Load is a trademark of Linear Technology Corporation.
14901fa LT/TP 0897 4K REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1996
Linear Technology Corporation
●
1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900
12
●
●
FAX: (408) 434-0507 TELEX: 499-3977 www.linear-tech.com
Linear [ Linear ]
