Currently, there are many manufacturers in China that produce type-C SMT male connectors. They can not only process and produce various C-type USB interfaces for various mobile phone brands, but also independently design and produce products with C-type USB interfaces, such as chargers. We all know that the C-type USB interface can transmit large amounts of current and can achieve fast charging for electronic devices. In order to improve the safety of using type-c SMT male heads, overvoltage protection needs to be designed.

The method of implementing overvoltage protection for type-c SMD male head is very simple, simply placing an overvoltage protection chip on the pin circuit. When a voltage above the chip threshold is detected on these circuits, the internal high-voltage power switch can be disconnected, while the rest of the system is isolated from the high-voltage state present on the connector. The overvoltage protection method for CC and SBU channels is similar to this principle, but the channel functions are different and need to be handled separately.

The CC channel is a configuration channel for type-c chip male connectors, which includes functions such as detecting positive and negative plugs, detecting USB connections, identifying available voltage and current, establishing and managing connections between USB devices and VBUs, etc. The power switch tubes on the CC channel are powered by batteries. Under normal power supply conditions, the power switch tubes connected in series on the CC channel are conductive like wires and will not affect the configuration of the type-c chip male CC channel. However, if the power supply is insufficient, the power switch will automatically disconnect, causing the detection function of the CC channel to be blocked, thereby affecting the current transmission of the C-type USB interface and causing devices such as chargers to be unable to charge. To solve the overvoltage protection problem of switch tube disconnection, it is also possible to establish a connection between the USB device and VBUS, and continue to charge the battery, in front of the power switch tube and pull-down resistor RD. This RD resistor is effective when the power switch is disconnected, and the input is serial RD to ground; When the switch tube is connected, RD becomes invalid and the input terminal is disconnected from the ground.

Implementing ESD protection for all USB systems is a good design practice. In addition to the ESD risks that affect all USB systems, USB type-c also introduces some unique failure modes. These modes are due to a combination of two factors: USB PD high-power transmission and compact geometry.

Traditional USB systems can use USB PD to achieve high-power transmission, as long as they use USB 2.0 or 3.0 communication protocols. However, the risk of failure in non USB type-C applications is to some extent mitigated by the looser geometry of traditional USB connectors.

The USB type-c connector has a gap between one quarter of the pins of the A-type connector. The reduced pin spacing increases the possibility of twisting cables or disassembling connectors while receiving high currents/voltages, which can lead to catastrophic short circuits. The accumulation of debris inside the connector may have similar catastrophic effects.

In addition, the popularity of type-c has also led to a wide range of third-party cables and power adapters. Many of them cannot handle high currents supported by USB type-c and USB PD standards.

Compared to other versions of USB technology, compact connectors, fragments, and mechanical stresses that do not comply with the coupling of high current/voltage cables increase the risk of short circuits in USB type-C systems. If a short circuit occurs between adjacent VBUS and CC or SBU pins of a connector, downstream circuits may be damaged by a 20 volt surge.

In short, a USB C-type system with a USB PD can carry 20 volts and 5 amps. Combining compact connectors and sockets with narrow pin spacing, such high voltage and current amplifies the risk of short circuits (especially on CC and SBU pins adjacent to VBUS rails), making OVP protection necessary. Discrete components can be used to achieve comprehensive ESD and OVP for USB type-c systems, but this approach can generate solutions for dozens of components that may struggle to adapt to BOM and the space allocated to the solution. The alternative method of integrating ESD and OVP circuits into a single chip greatly simplifies the design and reduces the size of the solution.