4 System Level Solutions

TI offers an array of ESD diodes know as the ESD2CANxx devices to protect all different types of CAN transceivers in many different environments. They come in leaded, dual-channel packages with matched capacitance designed specifically for CAN bus ESD protection.

Here, ESD2CAN24-Q1 was paired with a TCAN1042V-Q1 CAN transceiver to demonstrate how it provides system-level ESD immunity in a 12 V automotive environment. Two boards were used for this experiment: one board with just the TCAN1042V-Q1 and the other board with both the ESD2CAN24-Q1 and the TCAN1042V-Q1.

To measure signal integrity, both boards were powered to 5 V and a 500 kHz (1Mbps) digital signal was forced on the TXD pins to simulate a HS CAN environment. An oscilloscope was connected to the CANH (line 1), CANL (line2), TXD (line 3), and RXD (line 4) to observe the results. As the results in Figure 4-2 and Figure 4-3 show, the ESD2CAN24-Q1 diode does not degrade the CANH and CANL signals at all.

To measure system-level ESD immunity, the CANH and CANL pins of both boards were struck with +/-30 kV ISO 10605 contact pulses. Since TCAN1042V-Q1 is only rated to withstand 8 kV ISO 10605 pulses, the system without a diode failed. The system with ESD2CAN24-Q1 survived since the ESD2CAN24-Q1 clamped the pulse to a low enough voltage for the transceiver to handle.