4 Example Setups of Using GFO Pin in Channel Expansion Based Applications

Conceptually – channel expansion via the GFO pin is very simple. Connect GFO to the control input (some type of enable pin) of the external transceiver and use the MCU to send SPI commands to the SBC that controls when the external transceiver is on and ready to communicate. This section is going to show some real examples used in multiple systems. There are three main examples that are shown: channel expansion with a CAN FD transceiver, channel expansion with a CAN FD SBC, and channel expansion with a LIN transceiver.

First, channel expansion with a CAN FD transceiver. This example utilizes a TCAN2847-Q1 or TCAN2857-Q1 as the SBC and the TCAN1044A-Q1 as the external CAN transceiver.

Figure 4-1 CAN SBC Adding Additional CAN Channel with GFO Pin

In this instance of channel expansion, the reality is very close to the concept. The STB pin of the TCAN1044A-Q1 is controlled through the GFO pin on the TCAN2847-Q1 device while VCC2 (5V) provides power to the external CAN transceiver. Note that the TCAN2847-Q1 family of SBC devices is not required for the application; any SBC with a GFO pin can be used for channel expansion.

Second, the channel expansion can also be used to facilitate another CAN SBC such as the TCAN1162x-Q1 family of devices.

Figure 4-2 CAN SBC Adding Additional CAN SBC with GFO Pin

This is very similar to the CAN channel expansion, except nSLP is now the enable pin that GFO controls. VCC1 from the primary SBC is used to power the integrated CAN transceiver within the TCAN1162x-Q1 device with the main supply voltage coming from the battery, which is the same as the TCAN2847-Q1 in this application.

The third example is using channel expansion with a basic LIN transceiver, such as the TLIN1029A-Q1.

Figure 4-3 CAN SBC Adding LIN Transceiver with GFO Pin

The channel expansion control line is the GFO pin, and nothing else has. However, for a LIN device the main supply voltage is battery. This means the battery supply is also powering the LIN device. For another level of control, the HSS4 output of the TCAN2847-Q1 device can be used as a load switch between the LIN transceiver and the battery.

There are numerous examples, but the general idea is the same across the applications: GFO controls the enable and disable inputs to the external transceiver and the primary SBC can be used to facilitate device power if not directly powering the external transceiver.