Datasheet

LTC1066-1
16
10661fa
1066-1 TA05
7.5V
–7.5V
7.5V
2ND ORDER BUTTERWORTH ANTI-
ALIASING FILTER PROVIDES –68dB
ATTENUATION TO INPUTS AT 2f
CLK
–7.5V
V
OUT
V
IN
f
CLK
C
F
R
F
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
C2
OUT A
–IN A
+IN A
V
–
V
+
CONNECT 1
FILTER
OUT
50/100
CLK
V
+
OUT B
+IN B
GND
FILTER
IN
COMP 2
CONNECT 2
COMP 1
V
–
0.1µF
0.1µF
0.1µF
LTC1066-1
20Ω
20Ω
R1
R2
0.1µF
C1
f
CUTOFF
= , =
f
CLK
50
f
CUTOFF
250
1
2πR
F
C
F
= 2Hz, SET R
F
= 80.6k, C
F
= 1µF AND C1 = 0.0027µF
1
2πR
F
C
F
f
–3dB
= 2•f
CUTOFF
(f
–3dB
IS THE –3dB FREQUENCY OF THE
2ND ORDER ANTI-ALIASING FILTER)
1
2π(R1 + R2)C1
= 0.707•f
–3dB
, R2 = 17.946•R1, C2 = 10•C1
FOR CUTOFF FREQUENCIES 2kHz TO 5kHz, SET R
F
= 20k,
C
F
= 1µF AND R1 + R2 ≤ 2k
FOR CUTOFF FREQUENCIES <2kHz, SET R1 + R2 = R
F
FOR EXAMPLE:
IF THE CUTOFF FREQUENCY OF LTC1066-1 IS 500Hz, THEN
f
–3dB
= 1000Hz
R1 + R2 = 80.6k, R1 = 4.22k AND R2 = 76.8k ROUNDED TO NEAREST 1% VALUE.
C2 = 0.027µF ROUNDED TO NEAREST STANDARD VALUE.
NOTE: R
F
SHOULD BE ≤100k TO MINIMIZE DC OFFSET TO ±5.5mV
DC Accurate Lowpass Filter with Input Anti-Aliasing
(f
CLK
≤ 250kHz)
TYPICAL APPLICATIO
U