TLE8250G

Functional Description

Data Sheet

7

Rev. 1.0, 2010-06-02

The TLE8250G is a High Speed CAN transceiver, operating as an interface between the CAN controller and the

physical bus medium. A HS CAN network is a two wire, differential network which allows data transmission rates

up to 1 MBaud. Characteristic for a HS CAN network are the two signal states on the CAN bus: “Dominant” and

“Recessive” (see Figure 3).

The pins CANH and CANL are the interface to the CAN bus and both pins operate as an input and as an output.

The pins RxD and TxD are the interface to the microcontroller. The pin TxD is the serial data input from the CAN

controller, the pin RxD is the serial data output to the CAN controller. As shown in Figure 1, the HS CAN

transceiver TLE8250G has a receive and a transmit unit, allowing the transceiver to send data to the bus medium

and monitor the data from the bus medium at the same time. The HS CAN transceiver TLE8250G converts the

serial data stream available on the transmit data input TxD, into a differential output signal on CAN bus, provided

by the pins CANH and CANL. The receiver stage of the TLE8250G monitors the data on the CAN bus and converts

them to a serial, single ended signal on the RxD output pin. A logical “Low” signal on the TxD pin creates a

“Dominant” signal on the CAN bus, followed by a logical “Low” signal on the RxD pin (see Figure 3). The feature,

broadcasting data to the CAN bus and listening to the data traffic on the CAN bus simultaneous is essential to

support the bit to bit arbitration inside CAN networks.

The voltage levels for HS CAN transceivers are defined by the ISO 11898-2 and the ISO 11898-5 standards. If a

data bit is “Dominant” or “Recessive” depends on the voltage difference between pins CANH and CANL:

V

In comparison to other differential network protocols the differential signal on a CAN network can only be larger or

equal to 0 V. To transmit a “Dominant” signal to the CAN bus the differential signal

V

To receive a “Recessive” signal from the CAN bus the differential

V

Partially supplied CAN networks are networks where the CAN bus participants have different power supply

conditions. Some nodes are connected to the power supply, some other nodes are disconnected from the power

supply. Regardless, if the CAN bus participant is supplied or not supplied, each participant connected to the

common bus media must not disturb the communication. The TLE8250G is designed to support partially supplied

networks. In Power Down mode, the receiver input resistors are switched off and the transceiver input is high

resistive.