3.6 Physical Layer Interface
For compatibility purposes with the PCA82C200, the SJA1000 includes an analog receive input comparator circuit. This integrated comparator can be used if the transceiver function is realized with discrete components.
If an external integrated transceiver circuit is used and the comparator bypass function is
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not enabled in the Clock Divider Register, the RX1 input has to be connected to a reference voltage of 2.5V (reference voltage output of existing transceiver circuits). Figure 6 shows the equivalent circuits for both configurations: CBP = active and CBP = inactive. Additionally the path for the wake-up signal is drawn. For all new applications where an integrated transceiver circuit is used, it is recommended to activate the comparator bypass function of the SJA1000 (Figure 7). If this function is enabled, a schmitt-trigger input is used and the internal propagation delay tD2 is much shorter as the delay tD1. of the receive comparator. This has a positive impact on the maximum bus length [6]. Additionally, it will reduce the supply current in sleep mode significantly.
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