LTC1562 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1562' PDF : 28 Pages View PDF
LTC1562
TYPICAL APPLICATIONS (Basic)
Dual 4th Order Lowpass Filters
RIN1
VIN2
5V
0.1µF
RIN3
VIN1
RIN2
1
20
INV B
INV C
RQ1
2
19 RQ2
V1 B
V1 C
R21
3
V2 B
18 R22
V2 C
5 V+ LTC1562 V– 16
6
SHDN
15
AGND
0.1µF
8
V2 A
R23
9
V1 A
13
V2 D
12 R24
V1 D
RQ3
10
INV A
11 RQ4
INV D
RIN4
1562 TA03a
VOUT2
–5V
VOUT1
SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.
PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V –
Amplitude Response
10
0
–10
–20
–30
–40
–50
–60
–70
–80
10k
BUTTERWORTH
f –3dB = 100kHz
100k
FREQUENCY (Hz)
1M
1562 TA03b
Quick Design Formulas for Some Popular Response Types:
R21, R23, RIN1, RIN3 =
Butterworth
(Maximally Flat Passband)
for fC 10kHz to 140kHz
10k
100kHz
ƒC
2
Chebyshev
(Equiripple Passband)
for fC 20kHz to 120kHz
14.24k
100kHz
ƒC
2
RQ1, RQ3 =
R22, R24, RIN2, RIN4 =
5.412k
100kHz
ƒC
10k
100kHz
ƒC
2
7.26k
100kHz
ƒC
7.097k
100kHz
ƒC
2
RQ2, RQ4 =
13.07k
100kHz
ƒC
17.53k
100kHz
ƒC
Bessel
(Good Transient Response)
for fC 10kHz to 70kHz
3.951k
100kHz
ƒC
2
5.066k
100kHz
ƒC
4.966k
100kHz
ƒC
2
3.679k
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.
Example: Butterworth response, fC = 50kHz. from the formulas above, R21 = R23 = RIN1 = RIN3 = 10k(100kHz/50kHz)2
= 40k. RQ1 = RQ3 = 5.412k(100kHz/50kHz) = 10.82k. R22 = R24 = RIN2 = RIN4 = 10k(100kHz/50kHz)2 = 40k.
RQ2 = RQ4 = 13.07k(100kHz/50kHz) = 26.14k. Use nearest 1% values.
1562 TA03 TABLE
14
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