MAX7421CUA+

Overview

The MAX7421CUA+ is a fifth-order, low-pass switched-capacitor filter (SCF) from the Analog Devices/MAXIM MAX7418–MAX7425 family. It features an elliptic response with a sharp rolloff transition ratio of 1.25 and typically provides 37dB of stopband rejection. Designed for single +5V supply operation, it draws 3mA in operating mode and reduces to 0.2μA in shutdown mode. The corner frequency is adjustable from 1Hz to 45kHz via a 100:1 clock-to-corner ratio using either an internal oscillator or external clock. Key electrical parameters include a typical output offset voltage of ±4mV, a power-supply rejection ratio (PSRR) of 70dB, and a total harmonic distortion plus noise (THD+N) of -78dB at 2kHz input.

Feature Summary

• Elliptic low-pass filter response providing steep rolloff characteristics suitable for anti-aliasing applications
• Clock-tunable corner frequency allowing precise control over the passband edge
• Integrated shutdown mode significantly reducing power consumption when inactive
• Low output offset voltage minimizing DC error in signal processing chains

Applications

• ADC anti-aliasing filtering
• DAC post-filtering
• CT2 base stations
• Speech processing

Procurement Notes

Verify the specific suffix 'CUA+' corresponds to the commercial temperature range and RoHS compliance status required for your design. Confirm package availability as distribution channels may vary. Ensure the ordering code matches the exact device variant needed for production integration.

Selection Notes

Select this component when a sharp elliptic rolloff is required for single-supply +5V systems. Consider the MAX7419 or MAX7420 if Bessel or Butterworth responses are preferred for phase linearity or flatness. Verify that the clock frequency requirements align with the 100:1 tuning ratio and available clock sources.

Part Context

This part belongs to the MAX7418–MAX7425 series of fifth-order switched-capacitor filters. It shares the same 8-pin μMAX package and pinout with other variants in the family, differing primarily in filter response type and operating voltage. The MAX7421 specifically offers the elliptic response with a 1.25 transition ratio optimized for high attenuation near the cutoff.

Replacement Considerations

Public confirmed substitute part numbers are not provided in the source documentation.