Short-to-VBUS Protection
Protection ICs that keep USB Type-C CC and SBU pins safe when they are shorted to VBUS.
What is it?
Short-to-VBUS is a specific failure mode in USB Type-C designs. The CC and SBU pins sit right next to the VBUS pins in the connector, so a bent pin, debris or a slanted plug-in can short them to VBUS, which carries 5 V, up to 20 V with USB PD, or up to 48 V with USB PD 3.1 EPR. Without protection, that voltage can instantly destroy the IC behind those pins (CC / PD controller, MUX or audio chip). A Short-to-VBUS protection IC puts a switch in series with each line. When the connector-side voltage rises above a safe level, the switch opens within tens of nanoseconds, so the high voltage never reaches the IC, and it closes again once the fault is gone.
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 see. 24 V tolerance covers USB PD SPR (up to 20 V); EPR designs (28-48 V) need a higher rating.
- Working voltage (signal side)
- Must match the CC / SBU normal range (typically 0-5 V).
- Capacitance
- SBU carries the DisplayPort AUX channel or analog audio, not the high-speed video lanes, so a few pF is fine (MI2330G-F33: about 6 pF and 1 GHz bandwidth on SBU). The CC switch is larger because it also passes VCONN power.
- Latch / hold behaviour
- Some Short-to-VBUS parts latch when triggered (need a power cycle to recover); others recover by themselves. MI2330G-F33 turns its switches back on about 0.5 ms after the fault is removed.
- Package
- A 4-channel protector IC replaces several discrete parts. MI2330G-F33 is a 3 x 3 mm TQFN (TQFN3x3-20) placed between the connector and the CC / SBU controller.
What Magnias offers
MI2330G-F33: 4-channel USB Type-C short-to-VBUS protection for CC1 / CC2 plus SBU1 / SBU2 (or D+ / D-). It tolerates 24 V DC on the connector side, opens in about 70 ns and recovers automatically, adds IEC 61000-4-2 protection (±8 kV contact, ±15 kV air) on the connector pins, passes 600 mA VCONN through its CC switches and integrates dead-battery resistors. TQFN3x3-20, -40 to +85 °C. It is the active part for new designs; older variants are discontinued.