The 33990 is a serial transceiver designed to provide bi-directional halfduplex communication meeting the automotive SAE Standard J-1850 Class B Data Communication Network Interface specification. It is designed to interface directly to on-board vehicle microcontrollers and serves to transmit and receive data on a single-wire bus at data rates of 10.4 kbps using Variable Pulse Width Modulation (VPWM). The 33990 operates directly from a vehicle's 12 V battery system and functions in a logic fashion as an I/O interface between the microcontroller's 5.0 V CMOS logic level swings and the required 0 V to 7.0 V waveshaped signal swings of the bus. The bus output driver is short circuit current limited. Features