Pin-compatible replacement for obsolete Fairchild TMC2242 filter

It reduces the complexity of traditional analogue anti-aliasing pre-filters without compromising signal bandwidth or attenuation and will operate at up to 40 MHz clock rate with maximum ripple of ±0.02 dB and high stop band rejection of ±59.4 dB. Operation is user-selectable as 2:1 decimation or 1:2 interpolation.

The coefficients of the LF2242 are fixed, the only user programming required being the selection of mode and rounding. The asynchronous three-state output enable control simplifies interfacing to a bus.
Data input can be at up to 40 MSPS an, up to the 40 MHz I./O limit, the output sample rate can be one half, equal to, or twice the input sample rate. The output date can be either two’s complement format or inverted offset binary format. To avoid truncation errors, the output date is always internally rounded before it is latched to the output register. Rounding is user-selectable from 8- to 16-bit values.