MAX7405EPA+

Overview

The MAX7405EPA+ is an 8th-order, lowpass, Bessel switched-capacitor filter operating from a single +3V supply. It draws 2mA in normal mode and 0.2µA in shutdown. The corner frequency ranges from 1Hz to 5kHz via a 100:1 clock-to-corner ratio using internal or external clocks. Key parameters include ±5mV output offset, -84dB THD+N, and 60dB PSRR. It features a low-pass Bessel response for fast settling and minimal overshoot.

Feature Summary

• Provides 8th-order lowpass Bessel filtering with fast settling times suitable for multiplexed inputs.
• Features a low-power shutdown mode reducing current consumption to 0.2µA.
• Offers flexible clocking options including self-clocking via external capacitor or external clock input.

Applications

• ADC anti-aliasing
• Post-DAC filtering
• Speech processing

Procurement Notes

Verify the package type matches the required footprint, as the 'E' suffix indicates an industrial temperature range (-40°C to +85°C) while 'C' denotes commercial range. Confirm the '+' suffix ensures lead-free compliance. Cross-reference the specific ordering code against official manufacturer documentation to ensure correct voltage and temperature specifications.

Selection Notes

Select this component when a single +3V supply is available and low power consumption is critical. The fixed Bessel response simplifies design by eliminating complex pole-zero calculations. Ensure the application requires a maximum corner frequency of 5kHz and can accommodate the necessary clock frequency requirements relative to the desired cutoff.

Part Context

This device belongs to the MAX7401/MAX7405 family of switched-capacitor filters. The MAX7405 variant is specifically designed for +3V operation, whereas the MAX7401 supports +5V supplies. Both share identical electrical characteristics regarding filter order, response type, and pinout configurations within the 8-pin SOIC and PDIP packages.

Replacement Considerations

The MAX7401 serves as a direct functional substitute if the system operates on a +5V supply instead of +3V. Other members of the MAX740x series may offer different filter responses but require verification of pin compatibility and electrical parameter alignment.

FAQ

How is the corner frequency determined?

The corner frequency is set by the clock frequency divided by 100. It can be controlled via an external clock source or an internal oscillator defined by a capacitor connected between the CLK and GND pins.

What is the purpose of the OS pin?

The Offset Adjust (OS) pin allows for adjustment of the DC output level. Connecting it to the COM pin sets the default bias, while applying an external voltage enables DC level shifting.

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. Driving it high restores normal operation.