The power networks in automotive systems experience harsh conditions because of crank drops and inductive spikes and ESD events and occasional load-dump surges.
The following guide explains how to select the correct Diodes Incorporated device and how a seasoned Diodes Incorporated Distributor assists with fast delivery. The selection of TVS diodes for protection purposes equals the importance of the converter they protect. The first requirement demands you to identify all potential threats which affect your system.
Identify events affecting your operations.
The 12V battery rail experiences two main types of transients during cranking and ISO-style events and alternator load-dump occurrences. The main threats to signal lines (LIN, CAN, FlexRay, 100BASE-T1) come from ESD and fast EFT events. The protection requirements for your line depend on its operation as either a unidirectional battery network or its need for bidirectional data transfer through AC-coupled lines.
Select components based on their operating voltage ranges
The three essential parameters for TVS diodes include reverse standoff voltage (V_RM) and breakdown voltage (V_BR) and clamping voltage (V_C).
· The minimum reverse standoff voltage (V_RM) needs to exceed your system's worst-case operating voltage (e.g. 16 V+ for "12 V" systems and 32 V+ for "24 V" systems).
· The breakdown voltage (V_BR) of the device needs to be higher than the voltage at which it starts conducting to protect downstream components.
· The clamping voltage at I_PP shows the highest stress point which your load will face during a surge event so you need to match this value with the absolute maximum ratings of your protected ICs.
Determine voltage margins
The TVS rating system displays 10/1000 µs values yet battery events and load-dump occurrences in real-world scenarios extend beyond this duration and create more intense stress conditions. The selection process for TVS devices needs packages with high surge energy ratings because these devices offer complete protection against both long battery events and load-dump conditions.
Return path design
The operational effectiveness of TVS diodes depends on their return path design. The TVS diode should be placed near the surge source and the leads should remain short and wide while the ground path should have minimal inductance (chassis-referenced when needed). The distance between components through thin wires determines the amount of voltage increase that occurs because of inductive effects.
Waveform testing
The design requires testing under artificial supply sags and quick transients and ESD events. The protected node needs to be monitored through a scope to check V_C while tracking temperature increases at the junction and inspecting any potential failures in downstream components. The selection of a higher package class or a device with lower dynamic resistance becomes necessary when the clamp voltage exceeds acceptable levels.
AERI operates as a Diodes Incorporated distributor which enables customers to obtain exact order codes and photos and date codes and pack status before purchasing while also providing automotive-grade screening when needed. The selection requires particular threat elements and appropriate energy levels and correct layout arrangements and evidence-based product selection.
