Short-to-VBUS Protection
Specialised diodes that protect USB Type-C and other connector pins from accidental shorts to power rails.
What is it?
Short-to-VBUS is a specific failure mode in modern USB Type-C designs. A reversible Type-C connector can route VBUS (5 V or up to 24 V in PD) onto pins that normally carry low-voltage signals (CC1, CC2, SBU1, SBU2). Without protection, the 5-24 V VBUS will instantly destroy the connected IC (CC controller, MUX, or audio chip). A Short-to-VBUS diode blocks the high-voltage event in nanoseconds while presenting almost no capacitance to the normal signal.
When do you need it?
- USB Type-C CC1 / CC2 pin protection on host or device side.
- USB Type-C SBU1 / SBU2 pin protection (audio / DisplayPort alt-mode side-band).
- Any pluggable connector where high-voltage rails can be shorted to low-voltage pins (e.g., automotive infotainment connectors).
- USB-PD designs running 9 V / 15 V / 20 V — these voltages MUST be blocked from the signal side.
How to pick the right one
- Blocking voltage
- Must exceed the highest VBUS your design might encounter. 24 V minimum for USB-PD.
- Working voltage (signal side)
- Must match the CC / SBU normal range (typically 0-5 V).
- Capacitance
- Lower is better for SBU lines carrying DisplayPort or audio. <2 pF for HBR3 alt-mode.
- Latch / hold behaviour
- Some Short-to-VBUS parts latch when triggered (need power-cycle to recover); others are auto-recovering. Pick based on your fault-handling design.
- Package
- USB Type-C connectors are extremely space-constrained — DFN1006 or smaller preferred.
What Magnias offers
Magnias's flagship Short-to-VBUS device for the USB Type-C ecosystem is MI2330G-F33, a clean active part covering 24 V blocking with auto-recovery behaviour. Older MI2230 / MI2230A / MI2330A variants are EOL — please standardise on MI2330G-F33 for new designs.