45 kHz Bessel low-pass — the linear-phase choice for anti-aliasing
The Maxim Integrated MAX7419EUA+T is a 5th-order Bessel low-pass switched-capacitor filter with a fixed cutoff frequency of 45 kHz. The Bessel response gives near-constant group delay in the passband, so a pulse or data waveform keeps its shape — useful ahead of an ADC or after a DAC where phase distortion would smear the signal edges. The 5th-order roll-off provides sharp attenuation beyond 45 kHz while maintaining the linear-phase characteristic that a Butterworth or Chebyshev filter sacrifices.
Supply rail and package — what fits the board
If your system is 3.3 V, you need a separate 5 V rail or a charge pump. The package is an 8-uMAX/uSOP (3.00 mm wide MSOP/TSSOP footprint), which is compact enough for dense mixed-signal layouts but leaves room for the external capacitor that sets the switched-capacitor clock frequency. Surface-mount only — no through-hole option.