ZHCSEG6F December 2015 – May 2025 TCAN330 , TCAN330G , TCAN332 , TCAN332G , TCAN334 , TCAN334G , TCAN337 , TCAN337G
PRODUCTION DATA
The CAN bus has two logical states during operation: recessive and dominant. See Figure 6-3 and Figure 6-4.
Recessive bus state is when the high resistive internal input resistors of each node receiver bias the bus to a common mode of about 1.85V across the bus termination resistors. Recessive is equivalent to logic high and is typically a differential voltage on the bus of about 0V. Recessive state is also the idle state.
Dominant bus state is when the bus is driven differentially by one or more drivers. Current is induced to flow through the termination resistors and generate a differential voltage on the bus. Dominant is equivalent to logic low and is a differential voltage on the bus greater than the minimum threshold for a CAN dominant. A dominant state overwrites the recessive state.
During arbitration, multiple CAN nodes may transmit a dominant bit at the same time. In this case, the differential voltage of the bus is greater than the differential voltage of a single driver.
The host microprocessor of the CAN node uses the TXD terminal to drive the bus, and receives data from the bus on the RXD pin.
Transceivers with low power Standby Mode have a third bus state where the bus terminals are weakly biased to ground via the high resistance internal resistors of the receiver. See Figure 6-3 and Figure 6-4.
Figure 6-3 Bus
States (Physical Bit Representation)
The devices have four main operating modes:
| S | Device MODE | DRIVER | RECEIVER | RXD PIN |
|---|---|---|---|---|
| HIGH | Reduced Power Silent (Listen) Mode | Disabled (OFF)(2) | Enabled (ON) | Mirrors Bus State(1) |
| LOW/NC | Normal Mode | Enabled (ON) | Enabled (ON) |
| STB | Device MODE | DRIVER | RECEIVER | RXD Terminal |
|---|---|---|---|---|
| HIGH | Ultra Low Current Standby Mode | Disabled (OFF)(2) | Low Power Receiver and Bus Monitor Enabled (ON) | High (Recessive) until WUP, then filtered mirrors of Bus State (1) |
| LOW/NC | Normal Mode | Enabled (ON) | Enabled (ON) | Mirrors Bus State (1) |