The EMS3010 provides bidirectional SPI communications between two isolated devices through a single twisted-pair connection. Each EMS3010 encodes logic states into signals that are transmitted across an isolation barrier to another EMS3010. The receiving EMS3010 decodes the transmission and drives the slave bus to the appropriate logic states. The isolation barrier can be bridged by a simple pulse transformer to achieve hundreds of volts of isolation.

The EMS3010 drives differential signals using matched source and sink currents, eliminating the requirement for a transformer center tap and reducing EMI. Precision window comparators in the receiver detect the differential signals. The drive currents and the comparator thresholds are set by a simple external resistor divider, allowing the system to be optimized for required cable lengths and desired signal-to-noise performance.