MAX7422EUA+

Overview

The MAX7422EUA+ is a fifth-order, low-pass switched-capacitor filter with an elliptic response and a transition ratio of 1.6. It operates from a single +3V supply (range: 2.7V to 3.6V) and draws 2.6mA in operating mode, reducing to 0.2μA in shutdown mode. The corner frequency is adjustable from 100Hz 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 of 70dB, and a maximum capacitive load drive of 500pF. It is housed in an 8-pin μMAX package.

Feature Summary

• Elliptic filter response providing sharp rolloff with a 1.6 transition ratio for effective anti-aliasing.
• Low-power operation with a dedicated shutdown mode that reduces current consumption to 0.2μA.
• Flexible clocking options allowing for self-clocking via an external capacitor or external clock input for precise control.
• Offset adjust pin enables DC output level adjustment to accommodate various system bias requirements.

Applications

• ADC anti-aliasing
• DAC postfiltering
• CT2 base stations
• Speech processing

Procurement Notes

Verify the component against official Analog Devices documentation to confirm the specific elliptic response and +3V operating voltage. Ensure the ordering suffix matches the required temperature range and RoHS compliance status. Cross-reference the manufacturer part number with authorized distributors to validate authenticity and traceability before procurement.

Selection Notes

Select this device when a steep rolloff is required within a low-voltage, single-supply environment. The elliptic response is optimal for applications demanding high stopband rejection near the passband edge. Consider the internal oscillator convenience versus external clock precision based on the specific corner frequency stability requirements of the design.

Part Context

This component belongs to the MAX7418–MAX7425 family of fifth-order, low-pass switched-capacitor filters. While sharing similar architectures and packages, members of this series differ in filter response types (elliptic, Bessel, Butterworth) and operating voltages (+5V vs. +3V). The MAX7422 specifically combines the elliptic response with +3V single-supply operation.

Replacement Considerations

Direct substitutes within the same family include the MAX7418EUA+, which offers identical elliptic characteristics but requires a +5V supply instead of +3V. Designers must verify supply voltage compatibility and ensure that the clock-to-corner frequency scaling remains consistent if replacing with other variants in the series.

FAQ

How is the corner frequency determined for the MAX7422?

The corner frequency is set by the clock frequency divided by 100. It can be generated internally using a capacitor connected to the CLK pin or provided externally.

What is the purpose of the OS pin?

The OS (Offset Adjust) pin allows for the adjustment of the DC output level. It should be connected to COM if no offset adjustment is needed.

Does the MAX7422 support dual-supply operation?

Yes, while designed for single +3V supply, it can operate with dual supplies by connecting COM to system ground and GND to the negative supply.