Datasheet

16
LTC1562
1562fa
(Basic)
TYPICAL APPLICATIONS
U
Amplitude Response
8th Order Bandpass Filter, Single 5V Supply,
–3dB Bandwidth =
Center Frequency
10
R21 = R23 = 10.6k
Quick Design Formulas for Center Frequency f
C
(Recommended Range 40kHz to 140kHz):
2
100kHz
ƒ
C
R
Q1
= R
Q3
= 164.6k
100kHz
ƒ
C
100kHz
ƒ
C
+ 319kHz
R
Q2
= R
Q4
= 143.2k
R
IN2
= R
IN4
=
100kHz
ƒ
C
+ 294kHz
100kHz
ƒ
C
+ 286kHz
R22 = R24 = 9.7k
100kHz
ƒ
C
100kHz
ƒ
C
C
IN1
= C
IN3
= 159pF
2
10k
R
Q1
R22R
Q1
C
IN1
(10k)(10.6pF)
Notes: R
Q1
, R22 and C
IN1
should be rounded to the nearest standard finite-tolerance value before using these
values in the later formulas.
Example: Center frequency f
C
of 80kHz. The formulas give R21 = R23 = 16.56k, nearest standard 1% value 16.5k.
R
Q1
= R
Q3
= 51.56k, nearest 1% value 51.1k. R22 = R24 = 15.15k, nearest 1% value 15k. R
Q2
= R
Q4
= 47.86k,
nearest 1% value 47.5k. C
IN1
= C
IN2
= 31.11pF using 51.1k for R
Q1
, nearest standard 5% capacitor value 33pF.
This and the 1% value R22 = 15k also go into the calculation for R
IN2
= R
IN4
= 65.20k, nearest 1% value 64.9k.
1562 TA07 TABLE
1
2
3
5
6
8
9
10
20
19
18
16
15
13
12
11
INV B
V1 B
V2 B
V
+
SHDN
V2 A
V1 A
INV A
INV C
V1 C
V2 C
V
–
AGND
V2 D
V1 D
INV D
LTC1562
R
IN2
R
IN4
V
IN
V
OUT
1562 TA07a
5V
R
Q1
R21
R23
0.1µF
1µF
R
Q3
C
IN3
C
IN1
R24
R
Q4
R
Q2
R22
SCHEMATIC INCLUDES PIN NUMBERS FOR 20-PIN PACKAGE.
PINS 4, 7, 14, 17 (NOT SHOWN) ALSO CONNECT TO V
–
FREQUENCY (kHz)
40
GAIN (dB)
–30
–10
10
104
1562 TA07b
–50
–70
–40
–20
0
–60
–80
–90
56
72
88
48 112
64
80
96
120
f
CENTER
= 80kHz