MAX7409CUA+T

Overview

The MAX7409CUA+T is a fifth-order, lowpass switched-capacitor filter with a Bessel response. It operates from a single +5V supply and draws 1.2mA in active mode, reducing to 0.2µA in shutdown. The corner frequency is tunable between 0.001kHz and 15kHz via an internal or external clock using a fixed 100:1 ratio. Key electrical parameters include a typical output offset voltage of ±4mV, a power-supply rejection ratio of 70dB, and a maximum clock feedthrough of 5mVp-p. It is housed in an 8-pin µMAX package.

Feature Summary

• Provides a fifth-order Bessel lowpass response for fast settling and minimal overshoot
• Supports both self-clocking via external capacitor and external clock inputs
• Includes a dedicated offset adjust pin for DC level control
• Features a low-power shutdown mode to minimize current consumption

Applications

• ADC anti-aliasing filtering
• DAC post-filtering
• Speech processing systems

Procurement Notes

Verify the component against official Analog Devices documentation to confirm the specific Bessel response characteristic and +5V operating voltage requirements. Ensure that the ordering suffix matches the intended temperature range and packaging specifications before finalizing procurement decisions.

Selection Notes

Select this device when a maximally flat passband is not required and fast transient settling is critical. It is suitable for applications requiring a single +5V supply and precise corner frequency tuning through clock signal manipulation rather than passive component changes.

Part Context

This component belongs to the MAX7409/MAX7413 family of fifth-order switched-capacitor filters. While other variants like the MAX7410 offer Butterworth responses, the MAX7409 specifically provides Bessel characteristics optimized for preserving step input shapes in multiplexed data acquisition systems.

Replacement Considerations

The MAX7413 serves as a direct functional substitute but requires a +3V supply instead of +5V. Designers must verify supply voltage compatibility and ensure that the Bessel response characteristics align with the system's transient requirements.

FAQ

How is the corner frequency determined?

The corner frequency is set by dividing the clock frequency by 100, utilizing either an internal oscillator controlled by an external capacitor or an external clock source.

What is the purpose of the OS pin?

The Offset Adjust (OS) pin allows for the adjustment of the DC output level by connecting it to an external bias voltage through a resistive divider network.

How does the device handle high-frequency noise?

The fifth-order Bessel response attenuates frequencies above the corner frequency while maintaining linear phase characteristics to minimize overshoot and ringing.