General Description

The MAX7426/MAX7427 5th-order, lowpass, elliptic,

switched-capacitor filters (SCFs) operate from a single

+5V (MAX7426) or +3V (MAX7427) supply. The devices

draw only 0.8mA of supply current and allow corner fre-

quencies from 1Hz to 12kHz, making them ideal for

low-power post-DAC filtering and anti-aliasing applica-

tions. They can be put into a low-power mode, reducing

supply current to 0.2µA.

Two clocking options are available: self-clocking (through

the use of an external capacitor) or external clocking for

tighter cutoff-frequency control. An offset-adjust pin

allows for adjustment of the DC output level.

The MAX7426/MAX7427 deliver 37dB of stopband

rejection and a sharp rolloff with a transition ratio of

1.25. Their fixed response limits the design task to

selecting a clock frequency.

Applications

ADC Anti-Aliasing

CT2 Base Stations

Post-DAC Filtering

Speech Processing

Features

o 5th-Order, Elliptic Lowpass Filters

o Low Noise and Distortion: -80dB THD + Noise

o Clock-Tunable Corner Frequency (1Hz to 12kHz)

o Single-Supply Operation

+5V (MAX7426)

+3V (MAX7427)

o Low Power

0.8mA (Operating Mode)

0.2µA (Shutdown Mode)

o Available in 8-Pin µMAX/PDIP Packages

o Low Output Offset: ±4mV

5th-Order, Lowpass, Elliptic,

Switched-Capacitor Filters

________________________________________________________________ Maxim Integrated Products

1

OS

OUT

1

2

8

7

CLK

SHDN

IN

GND

COM

µMAX/PDIP

TOP VIEW

3

4

6

5

MAX7426

MAX7427

IN

CLK

OUT

GND

INPUT

0.1

µF

0.1

µF

CLOCK

SHDN

OUTPUT

COM

OS

MAX7426

MAX7427

Typical Operating Circuit

19-1710; Rev 0; 4/00

Pin Configuration

Ordering Information

PART

MAX7426CUA

MAX7426CPA

MAX7426EUA

-40°C to +85°C

0°C to +70°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

8 µMAX

8 Plastic DIP

8 µMAX

MAX7426EPA

-40°C to +85°C

8 Plastic DIP

PART

TRANSITION RATIO

OPERATING

VOLTAGE (V)

MAX7426

r = 1.25

+5

Selector Guide

MAX7427

r = 1.25

+3

MAX7427CUA

MAX7427CPA

MAX7427EUA

-40°C to +85°C

0°C to +70°C

0°C to +70°C

8 µMAX

8 Plastic DIP

8 µMAX

MAX7427EPA

-40°C to +85°C

8 Plastic DIP

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.