dc1941d DC1941D DC1941D LTC6820 isoSPI Demoboard (DC590B required) Demonstration circuit 1941 is an isoSPI™ transceiver board, based on Linear Technology’s LTC6820. The LTC6820 provides a method of interconnecting standard serial peripheral interface (SPI) devices using a single twisted pair connection. This proprietary 2-wire interface is called isoSPI. The LTC6820 encodes SPI signals, up to 1Mbps, into a differential isoSPI signal which is transmitted via a simple pulse transformer through a twisted pair. At the other end of the twisted pair, the isoSPI signal can be translated back to SPI (using another LTC6820).