MAX7421CUA+T

Overview

The MAX7421CUA+T is a fifth-order, low-pass switched-capacitor filter (SCF) from the MAX7418–MAX7425 series. It features an elliptic response with a sharp rolloff transition ratio of 1.25 and provides 37dB of stopband rejection. The device operates on a single +5V supply, drawing 3mA in active mode and 0.2μA in shutdown mode. It supports corner frequencies from 1Hz to 45kHz via a 100:1 clock-to-corner frequency ratio. The component is housed in an 8-pin μMAX package and functions within a temperature range of 0°C to +70°C.

Feature Summary

• Elliptic low-pass filter response with a 1.25 transition ratio for steep rolloff
• Switched-capacitor architecture supporting both internal oscillator and external clocking
• Low-power operation with dedicated shutdown mode reducing current to 0.2μA
• Integrated offset adjust pin for DC output level tuning

Applications

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

Procurement Notes

Verify that the ordering suffix '+T' corresponds to tape-and-reel packaging as specified by Analog Devices/Maxim Integrated. Confirm the 'C' suffix indicates the commercial temperature range of 0°C to +70°C. Ensure the RoHS status aligns with project requirements, noting that '+' typically denotes compliance. Cross-reference the manufacturer's official documentation for any specific handling or storage instructions related to the μMAX package.

Selection Notes

Select the MAX7421CUA+T when a sharp elliptic rolloff with a 1.25 transition ratio is required. This part is suitable for applications needing 37dB stopband rejection while operating from a single +5V supply. Consider this model over Bessel or Butterworth variants if phase linearity or passband flatness is less critical than attenuation speed. Verify that the 100:1 clock-to-corner frequency ratio meets the system's timing constraints.

Part Context

The MAX7421CUA+T belongs to the MAX7418–MAX7425 family of fifth-order, low-pass switched-capacitor filters. These devices emulate passive ladder networks using switched-capacitor integrators to minimize component sensitivity compared to cascaded biquadratic designs. The MAX7421 specifically offers an elliptic response optimized for sharp rolloff characteristics, distinguishing it from the Bessel and Butterworth variants within the same series.

Replacement Considerations

The MAX7425 serves as a direct functional substitute within the same series, offering identical elliptic characteristics but operating at +3V instead of +5V. For systems requiring a +5V supply with a different rolloff profile, the MAX7418 provides a similar elliptic response but with a 1.6 transition ratio and higher stopband rejection.