5th-Order, Lowpass, Switched-Capacitor Filters

 

Part Number	Replacement	Explanation

Description

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The MAX7418–MAX7425 5th-order, low-pass, switched-capacitor filters (SCFs) operate from a single +5V (MAX7418–MAX7421) or +3V (MAX7422–MAX7425) supply. These devices draw only 3mA of supply current and allow corner frequencies from 1Hz to 45kHz, making them ideal for low-power post-DAC filtering and anti-aliasing applications. They feature a shutdown mode that reduces supply current to 0.2µA.

Two clocking options are available: self-clocking (through the use of an external capacitor), or external clocking for tighter corner-frequency control. An offset adjust pin allows for adjustment of the DC output level.

The MAX7418/MAX7422 deliver 53dB of stopband rejection and a sharp rolloff with a 1.6 transition ratio. The MAX7421/MAX7425 achieve a sharper rolloff with a 1.25 transition ratio while still providing 37dB of stopband rejection. The MAX7419/MAX7423 Bessel filters provide low overshoot and fast settling, and the MAX7420/MAX7424 Butterworth filters provide a maximally flat passband response. Their fixed response simplifies the design task of selecting a clock frequency.

MAX7418, MAX7419, MAX7420, MAX7421, MAX7422, MAX7423, MAX7424, MAX7425: Typical Operating Circuit Enlarge+

Key Features

• 5th-Order, Lowpass Filters
  • Elliptic Response (MAX7418/MAX7421/MAX7422/MAX7425)
  • Bessel Response (MAX7419/MAX7423)
  • Butterworth Response (MAX7420/MAX7424)
• Clock-Turnable Corner Frequency (1Hz to 45kHz)
• Single-Supply Operation
  • +5V (MAX7418–MAX7421)
  • +3V (MAX7422–MAX7425)
• Low Power
  • 3mA (Operating Mode)
  • 0.2µA (Shutdown Mode)
• Available in 8-Pin µMAX® Package
• Low Output Offset: ±4mV

Applications/Uses

• ADC Anti-Aliasing
• CT2 Base Stations
• DAC Post-Filtering
• Speech Processing