MAX7422CUA+T

Overview

The MAX7422CUA+T is a fifth-order, low-pass switched-capacitor filter (SCF) from the Analog Devices MAX7418–MAX7425 series. It features an elliptic response with a transition ratio of 1.6 and operates on a single +3V supply. The device draws 3mA in operating mode and reduces to 0.2μA in shutdown mode. Corner frequencies are programmable from 1Hz to 45kHz via a 100:1 clock-to-corner ratio using either an internal oscillator or external clock. It provides 53dB stopband rejection, ±4mV output offset, and is housed in an 8-pin μMAX package.

Feature Summary

• Elliptic low-pass filter response with sharp rolloff
• Programmable corner frequency via clock input
• Low-power operation with deep shutdown mode
• Single-supply +3V compatibility

Applications

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

Procurement Notes

Verify the component matches the exact part number MAX7422CUA+T. Confirm the manufacturer is Analog Devices Inc. Ensure the suffix indicates RoHS compliance as per standard documentation practices. Check for physical damage upon receipt.

Selection Notes

Select this component when a single +3V supply is required. Choose the elliptic response for steep attenuation needs. Verify that the 100:1 clock-to-corner frequency ratio meets system timing constraints. Consider the 8-pin μMAX package size for PCB layout limitations.

Part Context

This part belongs to the MAX7418–MAX7425 family of fifth-order low-pass SCFs. While similar parts operate at +5V, the MAX7422 specifically supports +3V supplies. It shares the same pinout and general functionality as other members but differs in voltage range and specific filter characteristics like transition ratio.

Replacement Considerations

The MAX7422EUA is the industrial temperature grade equivalent (-40°C to +85°C). Other family members like MAX7418 require +5V and are not direct substitutes without supply modification.

FAQ

How is the corner frequency determined?

The corner frequency is set by the clock frequency divided by 100. It can be driven by an external clock or an internal oscillator controlled by an external capacitor.

What is the purpose of the SHDN pin?

Driving the SHDN pin low activates shutdown mode, reducing supply current to 0.2μA and placing the output in a high-impedance state.

Can the OS pin be left unconnected?

No. If offset adjustment is not needed, the OS pin must be connected to the COM pin to ensure proper operation.