General Description

The MAX7490/MAX7491 consist of two identical low-

2nd-order switched-capacitor building blocks. Each of

the two filter sections, together with two to four external

resistors, can generate all standard 2nd-order func-

tions: bandpass, lowpass, highpass, and notch (band

reject). Three of these functions are simultaneously

available. Fourth-order filters can be obtained by cas-

cading the two 2nd-order filter sections. Similarly, high-

er order filters can easily be created by cascading

multiple MAX7490/MAX7491s.

Two clocking options are available: self-clocking

(through the use of an external capacitor) or external

clocking for tighter cutoff frequency control. The clock-

to-center frequency ratio is 100:1. Sampling is done at

twice the clock frequency, further separating the cutoff

frequency and Nyquist frequency.

The MAX7490/MAX7491 have an internal rail splitter

that establishes a precise common voltage needed for

single-supply operation. The MAX7490 operates from a

single +5V supply and the MAX7491 operates from a

single +3V supply. Both devices feature a low-power

shutdown mode and come in a 16-pin QSOP package.

________________________Applications

Tunable Active Filters

Multipole Filters

ADC Anti-Aliasing

Post-DAC Filtering

Adaptive Filtering

Phase-Locked Loops (PLLs)

Set-Top Boxes

Features

o Dual 2nd-Order Filter in a 16-Pin QSOP Package

o High Accuracy

Q Accuracy: ±0.2%

Clock-to-Center Frequency Error: ±0.2%

o Rail-to-Rail Input and Output Operation

o Single-Supply Operation: +5V (MAX7490)

or +3V (MAX7491)

o Internal or External Clock

o Highpass, Lowpass, Bandpass, and Notch Filters

o Clock-to-Center Frequency Ratio of 100:1

o Internal Sampling-to-Center Frequency Ratio

of 200:1

o Center Frequency up to 40kHz

o Easily Cascaded for Multipole Filters

o Low-Power Shutdown: <1µA Supply Current

Dual Universal Switched-Capacitor Filters

________________________________________________________________ Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

LPA

LPB

BPB

NB/HPB

INVB

SB

COM

EXTCLK

CLK

TOP VIEW

MAX7490

MAX7491

QSOP

BPA

NA/HPA

SHDN

INVA

SA

GND

Pin Configuration

19-1768; Rev 0; 7/00

For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

Ordering Information

Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.

PART

TEMP. RANGE

PIN-

PACKAGE

SUPPLY

VOLTAGE

(+V)

MAX7490CEE

0

°C to +70°C

16 QSOP

5

MAX7490EEE

-40

°C to +85°C

16 QSOP

5

MAX7491CEE

0

°C to +70°C

16 QSOP

3

MAX7491EEE

-40

°C to +85°C

16 QSOP

3

Typical Application Circuit appears at end of data sheet.