DESCRIPTION
The main difference between the SA5217 and the SA5214 is that the SA5217 does not make the output of A1 and input of A2 accessible; instead, it brings out the output of A2 and the input of A8 thus activating the on-chip Schmitt trigger function by connecting two external capacitors. The result is that a much longer string of 1s and 0s, in the bit stream, can be tolerated. This ”system on a chip” features an auto-zeroed first stage with noise shaping, a symmetrical limiting second stage, and a matched rise/fall time TTL output buffer. The system is user-configurable to provide adjustable input threshold and hysteresis. The threshold capability allows the user to maximize signal-to-noise ratio, thereby insuring a low Bit Error Rate (BER). An auto-zero loop can be used to replace two input coupling capacitors with a single Auto Zero (AZ) capacitor. A signal absent flag indicates when signals are below threshold. The low signal condition forces the TTL output to the last logic state.
Philips
