ESD suppressor for high-speed communication network: Proposal to those seeking electric discharge (ESD) control for automotive Ethernet!
ESD suppressor is the component used to eliminate electric discharge from the circuit and transfer it to the ground.
The internal structure of an ESD suppressor entails a cavity, the resistance of which significantly decreases when a high voltage is applied. Consequently, ESD suppressor protects the electric equipment from static electricity. In normal conditions, however, the signal is not affected as the resistance value of the ESD suppressor is very high.
How to use
Implementing an ESD suppressor is very straightforward. Connect the ESD suppressor between the signal line and ground just below the connector (IF). In the case of BCI (Bulk Connect Injection) testing, a CMNF is required in the differential signal lines to eradicate electromagnetic noise. Using an ESD suppressor between the connector and CMNF helps suppress both static electricity and electrical noise and result in high-speed communication.
Comparing with TVS Diode
There are two types of components for ESD control, ESD suppressor and TVS diode. However, in the case of BCI testing for automotive Ethernet, using a TVS diode has its limitations. On the contrary, ESD suppressors can be placed directly after the connector, as shown in diagram ESD_1. Additionally, as shown in diagram ESD_2, TVS diodes need to be placed between the CMNF and Ethernet PHY, which consequently decreases the ESD protection capability and causes communication errors. Details here.
Component placement：(ESD_1) Connector-ESD-CMNF-PHY
Component placement：(ESD_2) Connector-CMNF-ESD-PHY
Panasonic’s ESD suppressor is high withstanding type according to AEC-Q200. (in-vehicle electric equipment ESD standard ISO 10605, atmospheric discharge 25kV) Moreover, because of the small electrostatic capacitance (0.1pF) and high rated voltage (DC50V), the risk of communication errors due to noise is negligible. Therefore, Panasonic ESD suppressor is highly suitable for automotive CAN and Ethernet.
ESD Suppressor, High withstanding type.