Datasheet

14 Maxim Integrated
Digitally-Programmed, Dual
2nd-Order Continuous Lowpass Filter
MAX270/MAX271
Figure 5. Cascading Filter Sections
Figure 6. Independent f
C
Programming without a µP
OUTBINA
58
OUPUT f
C
= 1kHz
80dB/dec. ROLLOFF
OUTA
INB
3
7
SHDN
4
+5V
-5V
V+
2
MAX270
A0
D5
D6
D4
D3
D2
D1
D0
12
V-
6
11
10
OP IN
20
GND
9
16
15
17
18
19
14
13
WR
CS
INPUT
SIGNAL
OUTBOP OUT
D6
MAX270
MAX690
WR
GND
FILTER SECTION A
+5V
OUTB
INB
V--5V
INA
SHDNSIGNAL B
SIGNAL A
+5V
OUTA
100kI
6
D6
D5
100kI
100k
I
4.7k
I
5
D5
D4
100k
I
4
D4
D3
100k
I
3
D3
D2
100kI
2
D2
D1
100k
I
1
D1
D0
A0
CS
100k
I
0
D0
PFO
WDI
RESET
VBATTV
OUT
V
CC
GND
PFI
0.1µF
0.1µF
+5V
0
1
2
34
5
V
CC
OC
8D
74HC373
1Q
TO D0
TO D1
TO D2
TO D3 TO D4
TO D5
+5V
+5V
GND
4Q
4D
3D
3Q
2Q
2D
1D
7D
7Q
6Q
6D
5D
5Q
C
V++5V
6
TO D6
8Q
FILTER SECTION B
STRAP PINS HIGH/LOW TO SET FILTER t
C
DATA.
FILTER DATA RELOADED ON EACH POWER-UP.