MAX7409CPA+

Overview

The MAX7409CPA+ 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 from 1Hz to 15kHz via an external clock or internal oscillator set by a capacitor on the CLK pin. Key electrical parameters include a maximum output offset voltage of ±25mV, a typical THD+N of -83dB, and a power-supply rejection ratio of 70dB. It is housed in an 8-pin Plastic DIP package.

Feature Summary

• Provides a fifth-order Bessel lowpass response for fast settling and minimal overshoot.
• Features a low-power shutdown mode that reduces current consumption significantly.
• Supports both self-clocking via an external capacitor and external clock inputs.
• Includes an offset adjust pin for DC output level tuning.

Applications

• ADC anti-aliasing
• DAC postfiltering
• Speech processing

Procurement Notes

Verify the component against official Analog Devices documentation to confirm the specific Bessel response characteristic and +5V operating voltage. Ensure the 8-pin PDIP package matches the design requirements. Cross-reference the ordering information to validate the temperature range and suffix details before finalizing procurement.

Selection Notes

Select this device when a maximally flat passband is not required, but rather fast settling time after channel switching is critical. The fixed Bessel response simplifies design compared to programmable filters. Verify that the available clock frequency range supports the desired corner frequency span up to 15kHz within the system constraints.

Part Context

This component belongs to the MAX7409/MAX7410/MAX7413/MAX7414 family of switched-capacitor filters. While other variants offer Butterworth responses or different supply voltages, the MAX7409 specifically provides the Bessel response optimized for multiplexed signal paths requiring rapid stabilization.

Replacement Considerations

The MAX7410 serves as a functional alternative if a Butterworth response is preferred over the Bessel characteristic. Other members of the MAX74xx series may require different supply voltages or offer varying package options, necessitating careful verification of pin compatibility and performance specifications.

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 generated internally using a capacitor connected to the CLK pin.

What is the purpose of the OS pin?

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

How does the shutdown mode function?

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