MAX7403ESA+ Maxim Integrated Products, MAX7403ESA+ Datasheet - Page 9

• Manufacturer Part Number: MAX7403ESA+
• Description: IC FILTER LOWPASS 8-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX7403ESA+

• Filter Type: Elliptic, Lowpass Switched Capacitor
• Frequency - Cutoff Or Center: 10kHz
• Number Of Filters: 1
• Max-order: 8th
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Number Of Channels: Single
• Cutoff Frequency: 10 KHz
• Supply Voltage (max): 5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 5 V
• Supply Voltage (min): 4.5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX7400/MAX7403/MAX7404/MAX7407 family of
8th-order, lowpass filters provides sharp rolloff with
good stopband rejection. All parts operate with a
100:1 clock-to-corner frequency ratio and a 10kHz
maximum corner frequency. These devices accept a
single +5V (MAX7400/MAX7403) or +3V (MAX7404/
MAX7407) supply. Figure 1 shows the functional dia-
gram.
Most switched-capacitor filters (SFCs) are designed
with biquadratic sections. Each section implements two
filtering poles, and the sections can be cascaded to
produce higher-order filters. The advantage of this
approach is ease of design. However, this type of
design is highly sensitive to component variations if any
section’s Q is high. The MAX7400 family uses an alter-
native approach, which is to emulate a passive network
using switched-capacitor integrators with summing and
scaling. The passive network can be synthesized using
CAD programs or can be found in many filter books.
Figure 2 shows a basic 8th-order ladder elliptic filter
structure.
A switched-capacitor filter that emulates a passive lad-
der filter retains many of the same advantages. The
component sensitivity of a passive ladder filter is low
when compared to a cascaded biquadratic design,
because each component affects the entire filter shape
rather than a single pole-zero pair. In other words, a
mismatched component in a biquadratic design has a
concentrated error on its respective poles, while the
same mismatch in a ladder filter design spreads its
error over all poles.
Lowpass, elliptic filters such as the MAX7400/MAX7403/
MAX7404/MAX7407 provide the steepest possible rolloff
with frequency of the four most common filter types
(Butterworth, Bessel, Chebyshev, and Elliptic). Figure 3
shows the 8th-order elliptic filter response. The high Q
value of the poles near the passband edge combined
with the stopband zeros allows for the sharp attenua-
tion characteristic of elliptic filters, making these
devices ideal for anti-aliasing and post-DAC filtering in
single-supply systems (see the Anti-Aliasing and Post-
DAC Filtering section).
In the frequency domain, the first transmission zero
causes the filter’s amplitude to drop to a minimum level.
Beyond this zero, the response rises as the frequency
increases until the next transmission zero. The stopband
begins at the stopband frequency, f
above f
S
, the filter’s gain does not exceed the gain at f
_______________________________________________________________________________________
Detailed Description
Elliptic Characteristics
S
. At frequencies
8th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
S
.
The corner frequency, f
the filter output attenuation falls just below the passband
ripple. The transition ratio is defined as the ratio of the
stopband frequency to the corner frequency:
The MAX7400/MAX7404 have a transition ratio of 1.5
and a typical stopband rejection of 82dB. The
MAX7403/MAX7407 have a transition ratio of 1.2 (pro-
viding the steepest rolloff) and a typical stopband
rejection of 60dB.
Figure 1. Functional Diagram
Figure 2. 8th-Order Ladder Filter Network
COM
CLK
IN
+
-
V
R1
IN
1
8
2
V
L1
DD
C2
CLOCK
INT
SCF
L3
C9
r = f
C
C4
BIAS
, is defined as the point where
S
/ f
MAX7400
MAX7403
MAX7404
MAX7407
C10
L5
C
OFFSET
LOGIC
ADJ
C6
C11
L7
C8
7
4
5
6
3
R2
SHDN
V
OUT
OS
GND
DD
V
0
9