11
LTC1062
1062fd
7th Order 100Hz Lowpass Filter with Continuous Output Filtering, Output Buffering and Gain Adjustment
FB
AGND
V
–
DIVIDER
RATIO
B
OUT
OUT
V
+
C
OSC
1
2
3
4
8
7
6
5
LTC1062
1µF
V
IN
2.6k
–5V
5V
5V
1062 TA13
10kHz
CLK IN
DC GAIN
1
10
R3
∞
3.57k
R4
0
32.4k
R1
14.3k
46k
R2
53.6k
274k
C1
0.1µF
0.01µF
C2
0.033µF
0.02µF
THE LTC1052 IS CONNECTED AS A 2ND ORDER SALLEN AND KEY LOWPASS FILTER WITH A CUTOFF
FREQUENCY EQUAL TO THE CUTOFF FREQUENCY OF THE LTC1062. THE ADDITIONAL FILTERING
ELIMINATES ANY 10kHz CLOCK FEEDTHROUGH PLUS DECREASES THE WIDEBAND NOISE OF THE FILTER
DC OUTPUT OFFSET (REFERRED TO A DC GAIN OF UNITY) = 5µV MAX
WIDEBAND NOISE (REFERRED TO A DC GAIN OF UNITY) = 60µV
RMS
R1
–
+
3
0.1µF
0.1µF
V
OUT
2
7
5V
6
8
4
1
C2
–5V
C1
R3
R4
R2
LTC1052
OUTPUT FILTER COMPONENT VALUES
Single 5V Supply 5th Order LP Filter
FB
AGND
V
–
DIVIDER
RATIO
B
OUT
OUT
V
+
C
OSC
1
2
3
4
8
7
6
5
LTC1062
1062 TA14
C C
V
IN
R
5V
10µF
SOLID
TANTALUM
5V
25k
5V
CLK
FOR A 10Hz FILTER: R = 29.4k, C = 1µF, f
CLK
= 1kHz
THE FILTER IS MAXIMALLY FLAT FOR
DC ACCURATE
OUTPUT
BUFFERED
OUTPUT
25k
12R
+
1
2πRC
=
f
C
1.84
TYPICAL APPLICATIO S
U
