MAX261ACNG Maxim Integrated Products, MAX261ACNG Datasheet - Page 19

• Manufacturer Part Number: MAX261ACNG
• Description: Active Filter
• Manufacturer: Maxim Integrated Products

Specifications of MAX261ACNG

• Number Of Channels: 2
• Cutoff Frequency: 57 KHz
• Supply Voltage (max): 12.6 V
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Supply Voltage (min): 4.74 V
• Package / Case: PDIP N-24
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 13. Second-Order Lowpass Characteristics
H
f
The procedure for most filter designs is to first convert
the required frequency response specifications to f
and Qs for the appropriate number of second-order
sections that implement the filter. This can be done by
using design equations or tables in available liter-
ature, or can be conveniently calculated using Maxim's
filter design software. Once the f
found, the next step is to turn them into the digital pro-
gram coefficients required by the MAX260/MAX261/
MAX262. An operating mode and clock frequency (or
clock/center frequency ratio) must also be selected.
Next, if the sample rate (f
significant errors, the selected f
corrected to account for sampling effects by using
Figure 20 or Maxim's design software. In most cases,
the sampling errors are small enough to require no cor-
rection, i.e., less than 1%. In any case, with or without
correction, the required f
ed from Tables 2 and 3. Maxim's filter design software
0
G s
OAP
( )
= ω
0
=
= Allpass output gain for DC < f < f
/ 2π
0.707 H
H
H
f
fp
C
OAP
OP
H
=
=
H
OLP
OLP
OP
=
f
f
O
O
s
s
H
2
2
X
OLP
1
Filter Design Procedure
______________________________________________________________________________________
−
+
−



1
s
s
X
2
(
(
−
ω
ω
Q
1
Q
1
2
o
o
2
0
CLK
Q
LOWPASS OUTPUT
1
s and Qs can then be select-
1
/
/
2
f(LOG SCALE)
−
Q
Q
1

 +

/2) is low enough to cause
)
)
4
Q
+
+
1
f
2
P
0
0



ω
ω
1
s and Qs have been
s and Qs should be
o
o
−
2
2
f
2
C
Q
1
2
CLK
Microprocessor Programmable

 +

2
/ 4
1
0
s
Universal Active Filters
Figure 14. Second-Order Highpass Characteristics
Figure 15. Second-Order Notch Characteristics
Table 6. Cascading Identical Bandpass
Filter Sections
Note: B = individual stage bandwidth, Q = individual
stage Q.
TOTAL SECTIONS
0.707 H
f
fp
H
C
OP
1
2
3
4
5
H
=
=
H
OHP
OHP
OP
=
f
f
H
H
O
O
H
ON2
ON1
H
ON
X
OHP
1





−



X
1
2
Q
1
−
Q
1
2
f
C
TOTAL B.W.
2
HIGHPASS OUTPUT
Q
1
1
f(LOG SCALE)
1.000 B
0.644 B
0.510 B
0.435 B
0.386 B
f(LOG SCALE)
2
−
1

 +

f
N
4
f
P
Q
1
2



1
−
2
Q
1
2

 +

2
TOTAL Q
1.00 Q
1.55 Q
1.96 Q
2.30 Q
2.60 Q
1





19