MAX7490CEE+T Maxim Integrated Products, MAX7490CEE+T Datasheet - Page 12

• Manufacturer Part Number: MAX7490CEE+T
• Description: IC FILTER SW CAP DUAL 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX7490CEE+T

• Filter Type: Universal Switched Capacitor
• Frequency - Cutoff Or Center: 40kHz
• Number Of Filters: 2
• Max-order: 2nd
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Dual Universal Switched-Capacitor Filters
Mode 2 Design Equations
Figure 5 shows the configuration of Mode 2N. This
mode extends the topology of Mode 3A to Mode 2,
where the highpass and lowpass outputs are summed
through two external resistors, R
lowpass notch filter that has higher frequency than the
one in Mode 2. Mode 2 is most useful in lowpass elliptic
designs. When cascading the sections of the
MAX7490/MAX7491, the highpass and lowpass outputs
can be summed directly into the inverting input of the
next section. Only one external op amp is needed.
Figure 5. Mode 2N, 2nd-Order Filter Providing a Lowpass Notch Output
12
f
f
Q
H
H
H
H
O
n
OLP
OBP
ON
ON
=
=
=
______________________________________________________________________________________
R
1
R
2
f
f
CLK
100
(
CLK
100
2
(
3
=
f
=
at f
→
−
−
1
R
R
R
R
0
+
1
=
1
2
3
Hz
1
f
R
R
⎛
⎜
⎝
CLK
V
+
IN
2
4
R
)
R
R
4
=
R
2
4
+
/ )
−
4
R
2
R
R
R1
1
2
2
=
COM
⎞
⎟
⎠
⎛
⎜
⎝
R
−
R
R
4
1
R
2
+
4
R
R4
R3
R2
2
⎞
⎟
⎠
H
and R
HP/N
L
+
, to create a
Σ
Mode 2N
S
-
C
C
∫
R
H
Mode 2N Design Equations
Figure 4. Mode 2, 2nd-Order Filter Providing a Highpass
Notch, Bandpass, and Lowpass Outputs
f
f
Q
H
O
n
BP
V IN
ON
=
=
=
∫
R
R
1
f
R1
f
100
CLK
(
CLK
100
3
2
f
COM
→
1
0
+
Hz
1
1
LP
R
R
+
+
R4
R3
R2
4
2
)
R
R
R
R
R
=
L
H
4
L
2
COM
⎛
⎜
⎝
R
R
G
H
HP/N
+
R
R
+
R
G
L
G
Σ
⎞
⎟
⎠
S
-
⎛
⎜
⎝
C
C
R
R
2
1
⎞
⎟
⎠
∫
⎛
⎜
⎝
LOWPASS
NOTCH
OUTPUT
R
4
R
+
4
R
BP
2
∫
⎞
⎟
⎠
LP