MAX7423EUA+T

Overview

The MAX7423EUA+T is a fifth-order, low-pass switched-capacitor filter (SCF) from the MAX7418–MAX7425 series. It features a Bessel response optimized for low overshoot and fast settling times. The device operates on a single +3V supply with a typical operating current of 3mA and a shutdown current of 0.2μA. It supports corner frequencies ranging from 1Hz to 45kHz via a 100:1 clock-to-corner ratio. Key electrical parameters include a maximum output offset voltage of ±25mV, a power-supply rejection ratio (PSRR) of 70dB, and an internal oscillator frequency constant of 110x10³/COSC(kHz).

Feature Summary

• Bessel filter response providing linear phase characteristics and minimal step-response overshoot.
• Low-power operation with a dedicated shutdown mode reducing supply current to microampere levels.
• Flexible clocking options supporting both external clock inputs and internal oscillator configurations.

Applications

• Anti-aliasing filters in multiplexed analog-to-digital converter (ADC) systems requiring rapid channel settling.
• Post-DAC filtering to smooth digital-to-analog converted signals.
• Speech processing circuits where signal waveform preservation is critical.

Procurement Notes

Verify the component authenticity by checking the manufacturer's marking against official datasheet specifications. Confirm the package type matches the required footprint and ensure the temperature range suffix aligns with environmental requirements. Cross-reference the ordering information to validate the specific variant before procurement.

Selection Notes

Select this component when a maximally flat passband or steep rolloff is not required, but rather a linear phase response is needed to preserve signal shape. Ensure the system can provide a stable clock signal within the 100:1 ratio constraint. Verify that the single +3V supply voltage meets the application's power budget and that the 8-pin μMAX package fits the design constraints.

Part Context

This part belongs to the MAX7418–MAX7425 family of fifth-order low-pass switched-capacitor filters. While other variants in the series offer Elliptic or Butterworth responses, the MAX7423 specifically provides a Bessel characteristic. It shares the same physical package and pinout as its siblings but differs in internal filter topology and frequency response behavior.

Replacement Considerations

Direct functional replacements within the same family include the MAX7419EUA, which offers identical Bessel characteristics but operates at +5V instead of +3V. For applications requiring different roll-off characteristics, consider the MAX7422EUA (Elliptic r=1.6) or MAX7424EUA (Butterworth), provided the supply voltage and response requirements are adjusted accordingly.

FAQ

How is the corner frequency determined for the MAX7423?

The corner frequency is set by the clock frequency divided by 100. This can be achieved using an external clock source or an internal oscillator defined by an external capacitor connected to the CLK pin.

What is the purpose of the OS pin on the MAX7423?

The Offset Adjust (OS) pin allows for DC level shifting. By connecting it to an external bias voltage through a resistive divider, users can adjust the DC output level relative to the Common Mode (COM) pin.

Can the MAX7423 operate with dual supplies?

Yes, while designed for single-supply operation (+3V), it can be used with dual supplies by connecting COM to system ground and GND to the negative supply rail.