Characteristics table for the input voltage range of COM

and OS. Changing the voltage on COM or OS significantly

from midsupply reduces the dynamic range.

Power Supplies

The MAX7418–MAX7421 operate from a single +5V sup-

ply and the MAX7422–MAX7425 operate from a single

+3V supply. Bypass VDD to GND with a 0.1μF capacitor.

If dual supplies are required, connect COM to the system

ground and GND to the negative supply. Figure 5 shows

an example of dual-supply operation. Single-supply and

dual-supply performance are equivalent. For either single-

supply or dual-supply operation, drive CLK and SHDN

from GND (V- in dual supply operation) to VDD. Use the

MAX7418–MAX7421 for ±2.5, and use the MAX7422–

MAX7425 for ±1.5V. For ±5V dual-supply applications,

refer to the MAX291/MAX292/MAX295/MAX296 and

MAX293/MAX294/MAX297 data sheets.

Input Signal Amplitude Range

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.

Anti-Aliasing and Post-DAC Filtering

When using the MAX7418–MAX7425 for anti-aliasing or

post-DAC filtering, synchronize the DAC (or ADC) and

the filter clocks. If the clocks are not synchronized, beat

frequencies may alias into the desired passband.

Harmonic Distortion

Harmonic distortion arises from nonlinearities within the

filter. These nonlinearities generate harmonics when a

pure sine wave is applied to the filter input. Tables 1, 2,

and 3 list typical harmonic distortion values with a 10kΩ

load at TA = +25°C.

Figure 5. Dual-Supply Operation

Table 1. MAX7418/MAX7421/MAX7422/MAX7425 Typical Harmonic Distortion

FILTER

fCLK

(MHz)

fIN

(kHz)

VIN

(Vp-p)

TYPICAL HARMONIC DISTORTION (dB)

2nd

3rd

4th

5th

MAX7418

2.2

2

4

<-80

<-80

<-80

<-80

1.5

2

<-80

<-80

<-80

<-80

MAX7421

2.2

2

4

<-80

<-80

<-80

<-80

1.5

2

<-80

<-80

<-80

<-80

MAX7422

4.0

4

2

<-80

<-80

<-80

<-80

2.2

2

<-80

<-80

<-80

<-80

MAX7425

4.0

4

2

<-80

<-80

<-80

<-80

2.2

2

<-80

<-80

<-80

<-80

www.analog.com

Analog Devices │ 12

MAX7418–MAX7425

5th-Order, Lowpass,

Switched-Capacitor Filters

VDD

V+

V-

IN

CLK

GND

INPUT

OUTPUT

OUT

0.1µF

0.1µF

CLOCK

*CONNECT SHDN TO V- FOR LOW-POWER SHUTDOWN MODE.

SHDN

COM

OS

MAX7418–

MAX7425

*

V+

V-