How to Make TVS Effective in Circuit Application
TVS devices shall be used on all data and power lines located on I/O connectors in and out of PCB. Make the TVS device as close to the noise source as possible to ensure that the surge voltage can be clamped before the pulse is coupled to the adjacent PCB wire.
How to make TVS effective in circuit application? The wiring of printed circuit board and the selection of circuit components are very important. Through the reasonable placement of TVS position, grounding selection, parasitic inductance and loop area processing, the scientific and reasonable PCB wiring and TVS tube selection can make TVS more efficient.
PCB Layout Guide
position
TVS devices shall be used on all data and power lines located on I/O connectors in and out of PCB. Make the TVS device as close to the noise source as possible to ensure that the surge voltage can be clamped before the pulse is coupled to the adjacent PCB wire. In addition, shorter TVS conductor shall be used for PCB to reduce surge energy consumption. Put sensitive wires in the center to avoid ESD during processing.
Grounding selection
If possible, the protection circuit shall shunt the surge voltage to the reference or case grounding. Shunting the surge voltage directly to the signal grounding of the integrated circuit will cause grounding rebound. The clamping performance of TVS diodes on a single grounded PCB can be improved by reducing the impedance with relatively short and wide grounding wires.
Parasitic inductance
The parasitic inductance of PCB layout and integrated circuit package will cause obvious overshoot of TVS clamping voltage. The inductance of PCB can be reduced by using short wires and multi-layer discrete grounding and power boards. Small SMT can reduce the inductance of the package.
Loop area
Reducing the loop area formed by high-speed data and grounding wires can reduce the impact of radiation and RF. Especially when the conductor is long, an effective way to alleviate the loop problem is to include a ground plate in the PCB design, increase the TVS tube, and provide isolation for separation intervals between integrated circuits. But it will increase the loop area.
