LTC1562 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1562' PDF : 28 Pages View PDF
TYPICAL APPLICATIONS (Basic)
8th Order Lowpass Filters
RIN1
VIN
5V
0.1µF
RIN2
1
20
RQ1
INV B
2
INV C
19
V1 B
V1 C
R21
3
V2 B
18
V2 C
5 V+ LTC1562 V– 16
6
15
SHDN
AGND
R23
8
13
V2 A
V2 D
9
V1 A
12
V1 D
RQ3
10
INV A
11
INV D
RIN4
RIN3
RQ2
R22
–5V
0.1µF
R24
RQ4
SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.
PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V –
VOUT
1562 TA04a
LTC1562
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
10k
Amplitude Response
CHEBYSHEV
fC = 100kHz
100k
FREQUENCY (Hz)
500k
1562 TA04b
Quick Design Formulas for Some Popular Response Types:
Butterworth
(Maximally Flat Passband)
for fC 10kHz to 140kHz
R21 = RIN1 =
10k
100kHz
ƒC
2
Chebyshev
(Equiripple Passband)
for fC 20kHz to 120kHz
R21
=
7.51k
100kHz
ƒC
2
, RIN1 = 2.2R21*
Bessel
(Good Transient Response)
for fC 10kHz to 70kHz
R21 =
RIN1
=
2.61k
100kHz
ƒC
2
RQ1
=
6.01k
100kHz
ƒC
R22 =
RIN2
=
10k
100kHz
ƒC
2
RQ1
=
119.3k
100kHz
ƒC
100kHz
ƒC + 560kHz
R22 = RIN2 =
14.99k
100kHz
ƒC
2
RQ1
=
3.63k
100kHz
ƒC
R22
=
RIN2
= 2.07k
100kHz
ƒC
2
RQ2
=
9k
100kHz
ƒC
R23 = RIN3 =
10k
100kHz
ƒC
2
RQ2
=
279.9k
100kHz
ƒC
100kHz
ƒC + 2440kHz
R23 = RIN3 =
7.15k
100kHz
ƒC
2
RQ2
=
5.58k
100kHz
ƒC
R23 =
RIN3
=
2.96k
100kHz
ƒC
2
RQ3
=
5.1k
100kHz
ƒC
R24 =
RIN4
=
10k
100kHz
ƒC
2
RQ3
=
118.1k
100kHz
ƒC
100kHz
ƒC + 530kHz
R24
=
26.7k
100kHz
ƒC
2
,
RIN4
=
R24*
2.2
RQ3
=
3.05k
100kHz
ƒC
R24
=
RIN4
= 3.14k
100kHz
ƒC
2
RQ4
=
25.63k
100kHz
ƒC
RQ4
=
8.75k
100kHz
ƒC
RQ4
=
2.84k
100kHz
ƒC
Notes: fC is the cutoff frequency: For Butterworth and Bessel, response is 3dB down at fC. For Chebyshev filters with
± 0.1dB passband ripple up to 0.95 fC, use LTC1562 “A” grade. *The resistor values marked with an asterisk (*) in the
Chebyshev formulas (R21 and R24) should be rounded to the nearest standard finite-tolerance value before computing
the values dependent on them (RIN1 and RIN4 respectively).
Example: Chebyshev response, fC = 100kHz. The formulas above give R21 = 7.51k, nearest standard 1% value 7.50k.
Using this 1% value gives RIN1 = 16.5k, already a standard 1% value. RQ1 = 18.075k, nearest 1% value 18.2k.
R22 = RIN2 = 14.99k, nearest 1% value 15k. RQ2 = 11.02k, nearest 1% value 11k. R23 = RIN3 = 7.15k, already a
standard 1% value. RQ3 = 18.75k, nearest 1% value 18.7k. R24 = 26.7k, already a standard 1% value. This gives
RIN4 = 12.14k, nearest 1% value 12.1k. RQ4 = 8.75k, nearest 1% value 8.66k.
1562 TA04 TABLE
15
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