MAX7408 Maxim, MAX7408 Datasheet - Page 10

• Manufacturer Part Number: MAX7408
• Description: 5th-Order / Lowpass / Elliptic / Switched-Capacitor Filters
• Manufacturer: Maxim

5th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
Figure 4. Dual-Supply Operation
Characteristics table for the input voltage range of COM
and OS. Changing the voltage on COM or OS signifi-
cantly from mid-supply reduces the dynamic range.
The MAX7408/MAX7411 operate from a single +5V
supply and the MAX7412/MAX7415 operate from a sin-
gle +3V supply. Bypass V
capacitor. If dual supplies are required, connect COM
10
Table 1. Typical Harmonic Distortion
V+
V-
*CONNECT SHDN TO V- FOR LOW-POWER SHUTDOWN MODE.
MAX7408
MAX7411
MAX7412
MAX7415
______________________________________________________________________________________
FILTER
CLOCK
INPUT
IN
CLK
(kHz)
f
500
100
500
100
500
100
500
100
CLK
MAX7408
MAX7411
MAX7412
MAX7415
V
GND
V+
DD
V-
DD
to GND with a 0.1µF
SHDN
COM
OUT
OS
Power Supplies
*
0.1 F
OUTPUT
(Hz)
200
200
200
200
f
1k
1k
1k
1k
IN
0.1 F
(Vp-p)
V
4
4
2
2
to the system ground and GND to the negative supply.
Figure 4 shows an example of dual-supply operation.
Single-supply and dual-supply performance are equiv-
alent. For either single-supply or dual-supply operation,
drive CLK and SHDN from GND (V- in dual supply
operation) to V
±2.5, and use the MAX7412/MAX7415 for ±1.5V. For
±5V dual-supply applications, see the MAX291/
MAX292/MAX295/MAX296 and MAX293/MAX294/
MAX297 data sheets.
The optimal input signal range is determined by observ-
ing the voltage level at which the signal-to-noise plus
distortion (SINAD) ratio is maximized for a given corner
frequency. The Typical Operating Characteristics show
the THD+Noise response as the input signal’s peak-to-
peak amplitude is varied.
When using the MAX7408/MAX7411/MAX7412/
MAX7415 for anti-aliasing or post-DAC filtering, syn-
chronize the DAC (or ADC) and the filter clocks. If the
clocks are not synchronized, beat frequencies may
alias into the desired passband.
Harmonic distortion arises from nonlinearities within the
filter. These nonlinearities generate harmonics when a
pure sine wave is applied to the filter input. Table 1 lists
typical harmonic distortion values with a 10kΩ load at
T
IN
A
= +25°C.
Anti-Aliasing and Post-DAC Filtering
-85.5
-88.2
-86.6
-88.2
2nd
-90
-88
-87
-90
TYPICAL HARMONIC DISTORTION (dB)
DD
Input Signal Amplitude Range
. Use the MAX7408/MAX7411 for
-78.4
-83.1
-93.1
-85.1
3rd
-80
-86
-86
-87
Harmonic Distortion
-92.8
-88.9
4th
-93
-92
-92
-90
-90
-90
-86.9
-89.5
-85.6
-85.7
5th
-88
-88
-90
-90