5th-Order, Lowpass,

Switched-Capacitor Filters

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7

NAME

FUNCTION

1

COM

Common Input Pin. Biased internally at midsupply. Bypass COM externally to GND with a 0.1µF capacitor.

To override internal biasing, drive COM with an external supply.

2

IN

Filter Input

PIN

3

GND

Ground

4

VDD

Positive Supply Input: +5V for MAX7409/MAX7410, +3V for MAX7413/MAX7414.

8

CLK

Clock Input. Connect an external capacitor (COSC) from CLK to ground: fOSC (kHz) = 30 x 103 / COSC (pF).

To override the internal oscillator, connect CLK to an external clock: fC = fCLK /100.

7

SHDN

Shutdown Input. Drive low to enable shutdown mode; drive high or connect to VDD for normal operation.

6

OS

Offset Adjust Input. To adjust output offset, connect OS to an external supply through a resistive voltage-

divider (Figure 3). Connect OS to COM if no offset adjustment is needed. Refer to the

Offset and Common-

Mode Input Adjustment section.

5

OUT

Filter Output

Pin Description

_______________Detailed Description

The MAX7409/MAX7413 Bessel filters provide low over-

shoot and fast settling responses, and the MAX7410/

MAX7414 Butterworth filters provide a maximally flat

passband response. All parts operate with a 100:1

clock-to-corner frequency ratio and a 15kHz maximum

corner frequency.

Bessel Characteristics

Lowpass Bessel filters such as the MAX7409/MAX7413

delay all frequency components equally, preserving the

shape of step inputs (subject to the attenuation of the

higher frequencies). Bessel filters settle quickly—an

important characteristic in applications that use a multi-

plexer (mux) to select an input signal for an analog-to-

digital converter (ADC). An anti-aliasing filter placed

between the mux and the ADC must settle quickly after

a new channel is selected.

Butterworth Characteristics

Lowpass Butterworth filters such as the MAX7410/

MAX7414 provide a maximally flat passband response,

making them ideal for instrumentation applications that

require minimum deviation from the DC gain throughout

the passband.

Typical Operating Characteristics (continued)

(VDD = +5V for MAX7409/MAX7410, VDD = +3V for MAX7413/MAX7414, fCLK = 100kHz, SHDN = VDD, COM = OS = VDD / 2, TA = +25°C,

unless otherwise noted.)

-4.50

-4.00

-4.25

-3.50

-3.75

-3.25

-3.00

-40

20

40

-20

0

60

80

100

OUTPUT OFFSET VOLTAGE

vs. TEMPERATURE

TEMPERATURE (°C)

VDD = +3V

VDD = +5V

-5.0

-4.0

-4.5

-3.0

-3.5

-2.5

-2.0

2.5

3.5

4.0

3.0

4.5

5.0

5.5

OUTPUT OFFSET VOLTAGE

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)