Datasheet MAX7409CPA, MAX7409CUA, MAX7413CPA, MAX7413CUA, MAX7413EPA Datasheet (Maxim)

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General Description

The MAX7409/MAX7410/MAX7413/MAX7414 5th-order,
lowpass, switched-capacitor filters (SCFs) operate from
a single +5V (MAX7409/MAX7410) or +3V (MAX7413/
MAX7414) supply. These devices draw only 1.2mA of
supply current and allow corner frequencies from 1Hz
to 15kHz, making them ideal for low-power post-DAC
filtering and anti-aliasing applications. They feature a
shutdown mode, which reduces the supply current to

0.2µA.
Two clocking options are available on these devices:

self-clocking (through the use of an external capacitor)
or external clocking for tighter corner-frequency control.
An offset adjust pin allows for adjustment of the DC out­put level.

The MAX7409/MAX7413 Bessel filters provide low over­shoot and fast settling, while the MAX7410/MAX7414
Butterworth filters provide a maximally flat passband
response. Their fixed response simplifies the design
task to selecting a clock frequency.

Applications

ADC Anti-Aliasing CT2 Base Stations
DAC Postfiltering Speech Processing
Air-Bag Electronics

Features

♦ 5th-Order Lowpass Filters

Bessel Response (MAX7409/MAX7413)
Butterworth Response (MAX7410/MAX7414)

♦ Clock-Tunable Corner Frequency (1Hz to 15kHz)
♦ Single-Supply Operation

+5V (MAX7409/MAX7410)
+3V (MAX7413/MAX7414)

♦ Low Power

1.2mA (operating mode)

0.2µA (shutdown mode)

♦ Available in 8-Pin µMAX/DIP Packages
♦ Low Output Offset: ±4mV

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

________________________________________________________________

Maxim Integrated Products

1

OS

OUTV

DD

1
2

87CLK

SHDNIN

GND

COM

µMAX/DIP

TOP VIEW

3

4

6

5

MAX7409
MAX7410
MAX7413
MAX7414

Typical Operating Circuit

19-4766; Rev 1; 9/98

Pin Configuration

Ordering Information

PART FILTER RESPONSE

OPERATING

VOLTAGE (V)

MAX7409 Bessel +5
MAX7410 Butterworth +5

Selector Guide

PART

MAX7409CPA
MAX7409EUA
MAX7409EPA -40°C to +85°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

8 Plastic DIP
8 µMAX

8 Plastic DIP
MAX7410CUA
MAX7410CPA
MAX7410EUA
MAX7410EPA -40°C to +85°C

-40°C to +85°C

0°C to +70°C

0°C to +70°C 8 µMAX

8 Plastic DIP

8 µMAX

8 Plastic DIP

Ordering Information continued at end of data sheet.

MAX7413 Bessel +3
MAX7414 Butterworth +3

MAX7409CUA

0°C to +70°C 8 µMAX

V

SUPPLY

0.1µF

INPUT

CLOCK

V

DD

SHDN

IN

MAX7409
MAX7410
MAX7413

CLK

MAX7414

GND

OUT

COM

OS

OUTPUT

0.1µF

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS—MAX7409/MAX7410

(VDD= +5V, filter output measured at OUT, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,

SHDN = VDD, f

CLK

= 100kHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VDDto GND..............................................................-0.3V to +6V

IN, OUT, COM, OS, CLK, SHDN ................-0.3V to (V

DD

+ 0.3V)

OUT Short-Circuit Duration...................................................1sec

Continuous Power Dissipation (T

A

= +70°C)

8-Pin DIP (derate 9.09mW/°C above +70°C)...............727mW

8-Pin µMAX (derate 4.1mW/°C above +70°C).............330mW

Operating Temperature Ranges

MAX74 _ _C_A ...................................................0°C to +70°C

MAX74 _ _E_A ................................................-40°C to +85°C

Storage Temperature Range.............................-65°C to +160°C

Lead Temperature (soldering, 10sec).............................+300°C

C

OSC

= 1000pF (Note 3)

VOS= 0 to V

DD

SHDN = GND, V

COM

= 0 to V

DD

(Note 1)

Input, COM externally driven

OS to OUT

Input, OS externally driven

fIN= 200Hz, VIN= 4Vp-p,
measurement bandwidth = 22kHz

VIN= V

COM

= V

DD

/ 2

V

COM

= V

DD

/ 2 (Note 2)

Output, COM unconnected

CONDITIONS

21 30 38f

OSC

Internal Oscillator Frequency

±0.1 ±10Input Leakage Current at OS

±0.1 ±10Input Leakage Current at COM

50 500C

L

10 1R

L

Resistive Output Load Drive

5Clock Feedthrough

110 180R

COM

Input Resistance at COM

V

COM

±0.1V

OS

2.3 2.5 2.7

100:1f

CLK

/ f

c

Clock-to-Corner Ratio

0.001 to 15f

c

Corner Frequency

V

COM

1A

OS

Offset Voltage Gain

-85

THD+N

Total Harmonic Distortion
plus Noise

10Clock-to-Corner Tempco

0.25 V

DD

-

0.25Output Voltage Range

±4 ±25V

OFFSET

Output Offset Voltage

-0.2 0 0.2

DC Insertion Gain with
Output Offset Removed

MIN TYP MAX

SYMBOLPARAMETER

V

CLK

= 0 or 5V

0.5V

IL

Clock Input Low

4.5V

IH

Clock Input High

±13.5 ±20I

CLK

Clock Output Current
(Internal Oscillator Mode)

V

V

µA

kHz

µA

µA

pF

kΩ

mVp-p

kΩ

V

V

V/V

dB

dB

mV

V

ppm/°C

kHz

UNITS

Maximum Capacitive Output
Load Drive

FILTER CHARACTERISTICS

CLOCK

MAX7409
MAX7410 -78

COM Voltage Range

2.0 2.5 3.0

Input Voltage Range at OS

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

_______________________________________________________________________________________ 3

5th-Order, Lowpass,

Switched-Capacitor Filters

ELECTRICAL CHARACTERISTICS—MAX7409/MAX7410

(VDD= +5V, filter output measured at OUT, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
SHDN = V

DD

, f

CLK

= 100kHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

ELECTRICAL CHARACTERISTICS—MAX7413/MAX7414

(VDD= +3V, filter output measured at OUT pin, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
SHDN = V

DD

, f

CLK

= 100kHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

CONDITIONS

MIN TYP MAX

SYMBOLPARAMETER

IN = COM (Note 4)

SHDN = GND

Operating mode, no load

0.5V

SDL

SHDN Input Low

4.5V

SDH

SHDN Input High

70PSRRPower-Supply Rejection Ratio

0.2 1I

SHDN

Shutdown Current

1.2 1.5Supply Current I

DD

4.5 5.5V

DD

Supply Voltage

V

V

dB

µA

mA

V

UNITS

SHDN Input Leakage Current V

SHDN

= 0 to V

DD

±0.2 ±10 µA

POWER REQUIREMENTS

SHUTDOWN

µA±0.1 ±10VOS= 0 to V

DD

Input Leakage Current at OS

µA±0.1 ±10

SHDN = GND, V

COM

= 0 to V

DD

Input Leakage Current at COM

Maximum Capacitive Output
Load Drive

UNITS

kHz

ppm/°C

V

mV
dB

dB
V/V

V

V

mVp-p

kΩ

pF

PARAMETER SYMBOL MIN TYP MAX

DC Insertion Gain with
Output Offset Removed

-0.2 0 +0.2

Output Offset Voltage V

OFFSET

±4 ±25

Output Voltage Range 0.25 V

DD

-

0.25

Clock-to-Corner Tempco 10

Total Harmonic Distortion
plus Noise

THD+N

-83

Offset Voltage Gain A

OS

1

Corner Frequency f

C

0.001 to 15

Clock-to-Corner Ratio f

CLK

/

f

C

100:1

COM Voltage Range V

COM

1.4 1.5 1.6

V

COM

±0.1

Clock Feedthrough 3
Resistance Output Load Drive R

L

10 1

C

L

50 500

CONDITIONS

V

COM

= V

DD

/ 2 (Note 2)

VIN= V

COM

= V

DD

/ 2

fIN= 200Hz, VIN= 2.5Vp-p,
measurement bandwidth = 22kHz

Input, COM externally driven

OS to OUT

Input, OS externally driven

(Note 1)

1.4 1.5 1.6

kΩInput Resistance at COM R

COM

110 180

Input Voltage Range at OS V

OS

MAX7413
MAX7414 -81

FILTER CHARACTERISTICS

VOutput, COM unconnected

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

4 _______________________________________________________________________________________

C

OSC

= 1000pF (Note 3)

CONDITIONS

21 30 38f

OSC

Internal Oscillator Frequency

MIN TYP MAX

SYMBOLPARAMETER

IN = COM (Note 4)

SHDN = GND

Operating mode, no load

V

CLK

= 0 or 3V

0.5V

SDL

SHDN Input Low

2.5V

SDH

SHDN Input High

70PSRRPower-Supply Rejection Ratio

0.2 1I

SHDN

Shutdown Current

1.2 1.5

2.7 3.6V

DD

Supply Voltage

0.5V

IL

Clock Input Low

2.5V

IH

Clock Input High

±13.5 ±20I

CLK

Clock Output Current
(Internal Oscillator Mode)

V

V

dB

µA

V

V

V

µA

kHz

UNITS

SHDN Input Leakage Current

V

SHDN

= 0 to V

DD

0.2 ±10 µA

FILTER CHARACTERISTICS

(VDD= +5V for MAX7409/MAX7410, VDD= +3V for MAX7413/MAX7414, filter output measured at OUT, 10kΩ || 50pF load to GND at
OUT, SHDN = V

DD

, f

CLK

= 100kHz, TA = T

MIN

to T

MAX

, unless otherwise noted.)

Note 1: The maximum f

C

is defined as the clock frequency f

CLK

= 100 x fCat which the peak S / (THD+N) drops to 68dB with a

sinusoidal input at 0.2f

C

.

Note 2: DC insertion gain is defined as ∆V

OUT

/ ∆VIN.

Note 3: f

OSC

(kHz) ≅ 30 x 103/ C

OSC

(pF).

Note 4: PSRR is the change in output voltage from a V

DD

of 4.5V and a VDDof 5.5V.

CLOCK

POWER REQUIREMENTS

SHUTDOWN

CONDITIONS UNITS

MIN TYP MAX

PARAMETER

mAI

DD

Supply Current

ELECTRICAL CHARACTERISTICS—MAX7413/MAX7414 (continued)

(VDD= +3V, filter output measured at OUT pin, 10kΩ || 50pF load to GND at OUT, OS = COM, 0.1µF capacitor from COM to GND,
SHDN = V

DD

, f

CLK

= 100kHz, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

fIN= 0.5f

C

-1 -0.74

fIN= f

C

-3.6 -3.0 -2.4

fIN= 4f

C

-41.0 -35

fIN= 7f

C

dB

-64.3 -58

fIN= 0.5f

C

dB

-0.3 0

fIN= 3f

C

fIN= f

C

-3.6 -3.0 -2.4

Insertion Gain Relative to
DC Gain

-47.5 -43

fIN= 5f

C

-70 -65

Insertion Gain Relative to
DC Gain

BESSEL FILTERS—MAX7409/MAX7413

BUTTERWORTH FILTERS—MAX7410/MAX7414

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

_______________________________________________________________________________________ 5

-56

-40

-48

-32

-8

0

-16

-24

8

0 1.0 1.5 2.0 2.50.5 3.0 3.5 4.0 4.5 5.0

MAX7409/MAX7413

FREQUENCY RESPONSE

(BESSEL)

MAX7409 toc01

INPUT FREQUENCY (kHz)

GAIN (dB)

fC = 1kHz

-70

-50

-60

-40

-10

0

-20

-30

10

0 1.0 1.5 2.0 2.50.5 3.0 3.5 4.0 4.5 5.0

MAX7410/MAX7414

FREQUENCY RESPONSE

(BUTTERWORTH)

MAX7409 toc02

INPUT FREQUENCY (kHz)

GAIN (dB)

fC = 1kHz

-250

-200

-100

-150

-50

0

0 0.4 0.60.2 0.8 1.0 1.2 1.4 1.6

MAX7409/MAX7413

PHASE RESPONSE

(BESSEL)

MAX7409 toc05

INPUT FREQUENCY (kHz)

PHASE SHIFT (DEGREES)

fC = 1kHz

-350

-300

-200

-250

-100

-50

-150

0

0 0.4 0.60.2 0.8 1.0 1.2 1.4 1.6

MAX7410/MAX7414

PHASE RESPONSE

(BUTTERWORTH)

MAX7409 toc06

INPUT FREQUENCY (kHz)

PHASE SHIFT (DEGREES)

fC = 1kHz

-3.2

-2.4

-3.0

-2.0

-0.8

-0.4

-1.2

-1.6

0

0 204 306 408 510102 612 714 816 9181.02k

MAX7409/MAX7413

PASSBAND FREQUENCY RESPONSE

(BESSEL)

MAX7409 toc03

INPUT FREQUENCY (Hz)

GAIN (dB)

fC = 1kHz

-3.5

-2.5

-3.0

-2.0

-0.5

0

-1.0

-1.5

0.5

0 204 306 408 510102 612 714 816 9181.02k

MAX7410/MAX7414

PASSBAND FREQUENCY RESPONSE

(BUTTERWORTH)

MAX7409 toc04

INPUT FREQUENCY (Hz)

GAIN (dB)

fC = 1kHz

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

1.19

2.5 3.53.0 4.0 4.5 5.0 5.5

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX7409 toc07

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

Typical Operating Characteristics

(VDD= +5V for MAX7409/MAX7410, VDD= +3V for MAX7413/MAX7414, f

CLK

= 100kHz, SHDN = VDD, COM = OS = VDD/ 2, TA= +25°C,

unless otherwise noted.)

LABEL

f

IN

(Hz)

f

C

(kHz)

A 200 1
B 1k 5

f

CLK

(kHz)

100
500

MEASUREMENT

BANDWIDTH (kHz)

22
80

Table A. THD+N vs. Input Signal
Amplitude Plot Characteristics

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= +5V for MAX7409/MAX7410, VDD= +3V for MAX7413/MAX7414, f

CLK

= 100kHz, SHDN = VDD, COM = OS = VDD/ 2, TA= +25°C,

unless otherwise noted.)

-90

-70

-80

-50

-60

-40

-30

-10

-20

0

0 1.0 2.0 3.0 4.0 5.00.5 1.5 2.5 3.5 4.5

MAX7409

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. INPUT SIGNAL AMPLITUDE

MAX7409 toc08

AMPLITUDE (Vp-p)

THD + NOISE (dB)

A

B

SEE TABLE A

-90

-70

-80

-50

-60

-40

-30

-10

-20

0

0 1.0 2.0 3.0 4.0 5.00.5 1.5 2.5 3.5 4.5

MAX7410

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. INPUT SIGNAL AMPLITUDE

MAX7409 toc09

AMPLITUDE (Vp-p)

THD + NOISE (dB)

A

B

SEE TABLE A

-90

-70

-80

-50

-60

-40

-30

-10

-20

0

0 0.5 1.0 1.5 2.0 2.5 3.0

MAX7413

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. INPUT SIGNAL AMPLITUDE

MAX7409 toc10

AMPLITUDE (Vp-p)

THD + NOISE (dB)

A

B

SEE TABLE A

-90

-70

-80

-50

-60

-40

-30

-10

-20

0

0 0.5 1.0 1.5 2.0 2.5 3.0

MAX7414

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. INPUT SIGNAL AMPLITUDE

MAX7409 toc11

AMPLITUDE (Vp-p)

THD + NOISE (dB)

A

B

SEE TABLE A

0

4

2

8

6

10

12

0 150 20050 100 250 300 350

INTERNAL OSCILLATOR PERIOD

vs. LARGE CAPACITANCE

MAX7409 toc14

CAPACITANCE (nF)

OSCILLATOR PERIOD (ms)

VDD = +5V

VDD = +3V

1.11

1.13

1.12

1.15

1.14

1.18

1.17

1.16

1.19

-40 0-20 20 40 60 80 100

SUPPLY CURRENT vs. TEMPERATURE

MAX7409 toc12

TEMPERATURE (°C)

SUPPLY CURENT (mA)

VDD = +5V

VDD = +3V

0

40

20

80

60

100

120

0 1500 2000500 1000 2500 3000 3500

INTERNAL OSCILLATOR PERIOD

vs. SMALL CAPACITANCE

MAX7409 toc13

CAPACITANCE (pF)

OSCILLATOR PERIOD (µs)

VDD = +5V

VDD = +3V

29.4

29.5

29.6

29.7

29.8

29.9

30.0

30.1

30.2

2.5 3.53.0 4.0 4.5 5.0 5.5

INTERNAL OSCILLATOR FREQUENCY

vs. SUPPLY VOLTAGE

MAX7409 toc15

SUPPLY VOLTAGE (V)

OSCILLATOR FREQUENCY (kHz)

C

OSC

= 1000pF

29.0

29.5

30.5

30.0

31.0

31.5

-40 0-20 20 40 60 80 100

INTERNAL OSCILLATOR FREQUENCY

vs. TEMPERATURE

MAX7409 toc16

TEMPERATURE (°C)

OSCILLATOR FREQUENCY FREQUENCY (kHz)

VDD = +5V

VDD = +3V

C

OSC

= 1000pF

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

_______________________________________________________________________________________ 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 V

DD

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

8 CLK

Clock Input. Connect an external capacitor (C

OSC

) from CLK to ground: f

OSC

(kHz) = 30 x 103/ C

OSC

(pF).

To override the internal oscillator, connect CLK to an external clock: fC= f

CLK

/100.

7

SHDN

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

6 OS

Offset Adjust Input. To adjust output offset, connect OS to an external supply through a resistive voltage­divider (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 over­shoot 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 multi­plexer (mux) to select an input signal for an analog-to­digital 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, f

CLK

= 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

MAX7409 toc17

TEMPERATURE (°C)

OFFSET VOLTAGE (mV)

VDD = +3V

VDD = +5V

-5.0

-4.0

-4.5

-3.0

-3.5

-2.5

-2.0

2.5 3.5 4.03.0 4.5 5.0 5.5

OUTPUT OFFSET VOLTAGE

vs. SUPPLY VOLTAGE

MAX7409 toc18

SUPPLY VOLTAGE (V)

DC OFFSET VOLTAGE (mV)

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

8 _______________________________________________________________________________________

The difference between Bessel and Butterworth filters
can be observed when a 1kHz square wave is applied
to the filter input (Figure 1, trace A). With the filter cutoff
frequencies set at 5kHz, trace B shows the Bessel filter
response and trace C shows the Butterworth filter
response.

Background Information

Most switched-capacitor filters (SCFs) are designed with
biquadratic sections. Each section implements two filter­ing poles, and the sections are cascaded to produce
higher-order filters. The advantage to this approach is
ease of design. However, this type of design is highly
sensitive to component variations if any section’s Q is
high. An alternative approach is to emulate a passive net­work using switched-capacitor integrators with summing
and scaling. Figure 2 shows a basic 5th-order ladder filter
structure.

A switched-capacitor filter such as the MAX7409/
MAX7410/MAX7413/MAX7414 emulates a passive ladder
filter. The filter’s component sensitivity is low when com­pared to a cascaded biquad design, because each
component affects the entire filter shape, not just one
pole-zero pair. In other words, a mismatched component
in a biquad design will have a concentrated error on its
respective poles, while the same mismatch in a ladder
filter design results in an error distributed over all poles.

Clock Signal

External Clock

The MAX7409/MAX7410/MAX7413/MAX7414 family of
SCFs is designed for use with external clocks that have
a 50% ±10% duty cycle. When using an external clock
with these devices, drive CLK with a CMOS gate pow­ered from 0 to VDD. Varying the rate of the external
clock adjusts the corner frequency of the filter as fol­lows:

fC= f

CLK

/ 100

Internal Clock

When using the internal oscillator, connect a capacitor
(C

OSC

) between CLK and ground. The value of the

capacitor determines the oscillator frequency as follows:

f

OSC

(kHz) = 30 x 103/ C

OSC

(pF)

Minimize the stray capacitance at CLK so that it does
not affect the internal oscillator frequency. Vary the rate
of the internal oscillator to adjust the filter’s corner fre­quency by a 100:1 clock-to-corner frequency ratio. For
example, an internal oscillator frequency of 100kHz
produces a nominal corner frequency of 1kHz.

Input Impedance vs. Clock Frequencies

The MAX7409/MAX7410/MAX7413/MAX7414’s input
impedance is effectively that of a switched-capacitor
resistor (see the following equation), and is inversely
proportional to frequency. The input impedance values
determined below represent the average input imped­ance, since the input current is not continuous. As a
rule, use a driver with an output impedance less than
10% of the filter’s input impedance. Estimate the input
impedance of the filter using the following formula:

ZIN= 1 / ( f

CLK

x 2.1pF)

For example, an f

CLK

of 100kHz results in an input

impedance of 4.8MΩ.

L4

C5C3

C1

V

IN

+

-

R

L

L2

R

S

Figure 2. 5th-Order Ladder Filter Network

A

2V/div

2V/div

2V/div

C

A: 1kHz INPUT SIGNAL
B: MAX7409 BESSEL FILTER RESPONSE; f

C

= 5kHz

C: MAX7410 BUTTERWORTH FILTER RESPONSE; f

C

= 5kHz

B

200µs/div

Figure 1. Bessel vs. Butterworth Filter Response

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

_______________________________________________________________________________________ 9

Low-Power Shutdown Mode

These devices feature a shutdown mode that is activat­ed by driving SHDN low. In shutdown mode, the filter’s
supply current reduces to 0.2µA and its output becomes
high impedance. For normal operation, drive SHDN
high or connect it to VDD.

__________Applications Information

Offset and Common-Mode

Input Adjustment

The COM pin sets the common-mode input voltage and
is biased at mid-supply with an internal resistor-divider.
If the application does not require offset adjustment,
connect OS to COM. For applications requiring offset
adjustment, apply an external bias voltage through a
resistor-divider network to OS such as shown in Fig­ure 3. For applications that require DC level shifting,
adjust OS with respect to COM. (Note: OS should not
be left unconnected.) The output voltage is represent­ed by this equation:

V

OUT

= (VIN- V

COM

) + V

OS

with V

COM

= VDD/ 2 (typical), and where (VIN- V

COM

)
is lowpass filtered by the SCF, and OS is added at the
output stage. See the

Electrical Characteristics

for the
voltage range of COM and OS. Changing the voltage
on COM or OS significantly from midsupply reduces
the filter’s dynamic range.

Power Supplies

The MAX7409/MAX7410 operate from a single +5V
supply and the MAX7413/MAX7414 operate from a sin­gle +3V supply. Bypass VDDto GND with a 0.1µF
capacitor. If dual supplies are required (±2.5V for
MAX7409/MAX7410, ±1.5V for MAX7413/MAX7414),
connect COM to system ground and connect GND to
the negative supply. Figure 4 shows an example of
dual-supply operation. Single- and dual-supply perfor­mance are equivalent. For either single- or dual-supply
operation, drive CLK and SHDN from GND (V- in dual­supply operation) to VDD. For ±5V dual-supply applica­tions, use the MAX291–MAX297.

Input Signal Amplitude Range

The optimal input signal range is determined by
observing the voltage level at which the Total Harmonic
Distortion + Noise is minimized for a given corner fre­quency. The

Typical Operating Characteristics

show
graphs of the devices’ Total Harmonic Distortion plus
Noise Response as the input signal’s peak-to-peak
amplitude is varied.

Anti-Aliasing and DAC Postfiltering

When using these devices for anti-aliasing or DAC
postfiltering, synchronize the DAC (or ADC) and the fil­ter clocks. If the clocks are not synchronized, beat fre­quencies will 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. Table 1 lists
typical harmonic-distortion values for the MAX7410/
MAX7414 with a 10kΩ load at TA= +25°C. Table 2 lists
typical harmonic-distortion values for the MAX7409/
MAX7413 with a 10kΩ load at TA= +25°C.

V

DD

V

SUPPLY

IN

CLK

GND

INPUT

OUTPUT

50k

50k

50k

OUT

0.1µF

0.1µF

0.1µF

CLOCK

SHDN

COM

OS

MAX7409
MAX7410

MAX7413
MAX7414

Figure 3. Offset Adjustment Circuit

V

DD

V+

V-

IN

CLK

GND

INPUT

OUTPUTOUT

0.1µF

CLOCK

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

SHDN

COM

OS

0.1µF

MAX7409
MAX7410
MAX7413
MAX7414

*

V+

V-

Figure 4. Dual-Supply Operation

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

10 ______________________________________________________________________________________

Table 2. MAX7409/MAX7413 Typical Harmonic Distortion

5th

3rd

-88.3

-87.9

-88.8

-86.9

-81

-85.4

-91.1-79

-87.9

-87.3

-86.4

-86

100

500

2

200

MAX7413

1k

100

500

f

CLK

(kHz)

4th

2nd

-88.4

-88.8

TYPICAL HARMONIC DISTORTION (dB)

-83.5

-82.5

4

200

1k

MAX7409

V

IN

(Vp-p)

f

IN

(Hz)

FILTER

Table 1. MAX7410/MAX7414 Typical Harmonic Distortion

5th

3rd

-86.4

-87.6

-88.5

-85.5

-74

-78

-82-67

-85.8

-87.1

-86.1

-85.3

100

500

2

200

MAX7414

1k

100

500

f

CLK

(kHz)

4th

2nd

-88.7

-86.7

TYPICAL HARMONIC DISTORTION (dB)

-84

-85

4

200

1k

MAX7410

V

IN

(Vp-p)

f

IN

(Hz)

FILTER

TRANSISTOR COUNT: 1457

Chip Information

Ordering Information (continued)

PART TEMP. RANGE PIN-PACKAGE

MAX7413CPA 0°C to +70°C 8 Plastic DIP

MAX7413EPA
MAX7414CUA
MAX7414CPA
MAX7414EUA -40°C to +85°C

0°C to +70°C

0°C to +70°C

-40°C to +85°C 8 Plastic DIP
8 µMAX
8 Plastic DIP
8 µMAX

MAX7414EPA -40°C to +85°C 8 Plastic DIP

MAX7413CUA

0°C to +70°C 8 µMAX

MAX7413EUA -40°C to +85°C 8 µMAX

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,

Switched-Capacitor Filters

______________________________________________________________________________________ 11

________________________________________________________Package Information

8LUMAXD.EPS

MAX7409/MAX7410/MAX7413/MAX7414

5th-Order, Lowpass,
Switched-Capacitor Filters

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

12

____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Package Information (continued)

PDIPN.EPS