Datasheet
16
LT1490A/LT1491A
sn1490, 14901afbs
LT/TP 0105 REV B • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2000
Ring-Tone Generator
RELATED PARTS
–
+
–
+
–
+
–
+
1490A TA03
R6
10k
R2
47k
R7
16k
R8
620k
R4
1.6M
R1
33k
R3
10k
R5
100k
R10
620k
C4
0.068µF
9
10
6
7
8
1
5
C3
0.047µF
C5
0.01µF
R13
130k
R12
10k
R15
47k
R14
10k
R24
420
C7
47µF
LOAD
UP TO
TEN
PHONES
R23
4.7k
R26
2k
Q5
2N3904
Q4
2N3906
Q2
IRF9620
–180V
POWER AMPLIFIER
SMOOTHING FILTER
20Hz OSCILLATORCADENCE OSCILLATOR
*LED OF OPTO1 ILLUMINATES WHEN THE PHONE IS OFF THE HOOK
SEE DESIGN NOTE DN134 FOR A DISCUSSION OF THE CIRCUIT
R18
100Ω
R17
620Ω
R16
100k
Z1
15V
100k
R25
4.7k
C6
0.033µF
R21
150Ω
R19
620Ω
Z2
15V
R9
300k
R11
10k
D1
1N4148
C2
0.47µF
C1
1µF
2
3
1/4 LT1491A
1/4 LT1491A
12
4
11
13
Q1
IRF628
Q3
2N3904
60V
14
1/4 LT1491A
OPTO1*
R20
100k
1/4 LT1491A
PART NUMBER DESCRIPTION COMMENTS
LT1366/LT1367 Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps 475µV V
OS(MAX)
, 500V/mV A
VOL(MIN)
, 400kHz GBW
LT1636 Single Over-The-Top Micropower Rail-to-Rail Input and Output 55µA Supply Current, V
CM
Extends 44V above V
EE
,
Op Amp Independent of V
CC
, MSOP Package, Shutdown Function
LT1638/LT1639 Dual/Quad 1.2MHz Over-The-Top Micropower, Rail-to-Rail 0.4V/µs Slew Rate, 230µA Supply Current per Amplifier
Input and Output Op Amps
LT1782 Micropower, Over-The-Top, SOT-23, Rail-to-Rail SOT-23, 800µV V
OS(MAX)
, I
S
=55µA (Max),
Input and Output Op Amp Gain-Bandwidth = 200kHz, Shutdown Pin
LT1783 1.2MHz, Over-The-Top, Micropower, Rail-to-Rail SOT-23, 800µV V
OS(MAX)
, I
S
=300µA (Max),
Input and Output Op Amp Gain-Bandwidth = 1.2MHz, Shutdown Pin
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
TYPICAL APPLICATIO
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