Universal Serial Bus (USB) is a standard developed in the mid-1990s to standardize the connection between computers and peripheral devices for communication and power supply. It replaces various early interfaces, such as serial/Parallel port, PS/2 and independent chargers for portable devices.

There are three connector sizes - standard, mini, and micro, models "A", "B", "AB" connectors and corresponding sockets, as well as the five data transmission modes summarized in Table 1:

USB type throughput direction total capacitance pins 1. X 1.5 Mbit/s (low speed) 12 Mbit/s (full speed) half duplex; Irreversible 30pF 4 2.0 480 Mbit/s (high-speed) half duplex; Irreversible 10pF 4-5 3.0 5 Gbit/s (SuperSpeed) full duplex; Irreversible 1pF 9 3.1/Gen2 10 Gbit/s (SuperSpeed+) full duplex; Irreversible 0.1-0.5pF 9 Type-C 10 Gbit/s (SuperSpeed+) full duplex; Reversible 0.1pF 24

Table 1: USB data transfer mode.

USB 3.1/Gen 2 is basically USB 3.0, doubling the speed to 10 Gbit/s. It is full duplex and irreversible, so the connector and socket must be aligned in the correct direction to be inserted. Its total capacitance is 0.1-0.5 pF.

The USB type c is 10 Gbit/s and reversible (similar to Apple's Lightning), with symmetrical 24 pins, so the connector will be connected to the first socket to try. Additional pins allow the use of C-type cables to support data protocols such as DisplayPort 1.3, PCI Express, and Base-t Ethernet. Figure 1 shows the pin diagram of the USB type C cable.

The connector and socket size of USB type C is smaller (similar to Lightning and Micro USB), making it more durable and capable of withstanding 10000 plugs and unplugs. This cable supports up to 100 W USB power mode, allowing for faster charging of smartphones and tablets. Currently, devices that can accommodate USB type C cables include Apple's 2015 MacBook, Google's Chromebook Pixel, Nokia's N1 tablet, smartphones such as OnePlus 2 and Le Superphone, as well as mobile storage devices such as LaCie and SanDisk.

Figure 1: USB type C pin diagram.

Comship has many low capacitance ESD surge suppressors for USB port protection. The recommended components for USB 3.0 are listed in Table 2, and the recommended PCB layout is shown in Figures 2 and 3. The recommended components and layout for USB 3.1 are shown in Figures 4 and 5. The recommended components for Type C are listed in Tables 3 and 3. The recommended circulating PCB layout is shown in Figure 6.

USB 2.0 D+, D - (USB 2.0 and 3.0 data cables combined into one)

Part Number VRWM IR (Max) VC Cj ESD (Contact) Package CPDQR5V0USP-HF 5 V1 μ A13V 0.6 pF ± 8 KV 0402

1-Line/Uni CPDQ5V0USP-HF 5 V1 μ A13V 0.6 pF ± 8 KV 0402

1-Line/Uni CPDQC5V0USP-HF 5 V1 μ A13V 0.6 pF ± 8 KV 0402C

1-Line/Uni CPDU5V0USP-HF 5 V1 μ A9.8V 0.5 pF ± 10 KV 0603

1-Line/Uni CPDUC5V0USP-HF 5 V1 μ A9.8V 0.5 pF ± 10 KV 0603C

1-Line/Uni CPDT-5V0UP-HF 5 V1 μ A12V 0.6 pF ± 10 KV SOT-23

2-Line/Uni

USB 3.0 Tx, Rx

Part number VRWM IR (maximum) VC Cj ESD (contact) package CPDQC5V0CSP-HF 5 V 100 A 15 V 0.3 pF ± 8 KV 0402C

1-Line/Bi CPDQC5V0USP-IPHF 5 V 100 nA 12 V 0.3 pF ± 10 KV 0402C

1 wire/Uni CPDA10R5V0P-HF 5 V 50 nA 9 V 0.25 pF ± 18 KV DFN10P

4-wire/Uni

VBUS 5V

Part number VRWM IR (maximum) VC Cj ESD (contact information) Package CPDQC5V0R-HF 5 V 90 nA 8 V 24 pF ± 30 KV 0402C

1-Line/Bi CPDUR5V0R-HF 5 V 90 nA 8 V 24 pF ± 30 KV 0603

1-Line/Bi CPDUC5V0R-HF 5 V 90 nA 8 V 24 pF ± 30 KV 0603C

1-Line/Bi CPDQR5V0HE-HF 5 V1 μ A11V 15 pF ± 30 KV 0402

1-Line/Bi CPDQC5V0HE-HF 5 V1 μ A 11 V 15 pF ± 30 KV 0402C

1-Line/Bi CPDUR5V0HE-HF 5 V1 μ A11V 15 pF ± 30 KV 0603

1-Line/Bi

Table 2: Recommended components for USB 3.0.

图2：usb 3.0建议使用三个组件的PCB布局图。

Figure 3: PCB layout diagram of two components recommended for USB 3.0.

The USB 3.1 A model has ESD requirements similar to USB 3.0 A, so the recommended PCB layout is the same, except for using ESD components with lower capacitors. The recommended USB 3.1 PCB layout is shown in Figures 4 and 5.

Figure 4: PCB layout diagram of three components recommended for USB 3.1.

Figure 5: PCB layout diagram of two components recommended for USB 3.1.

USB type C has a throughput of 10 Gbit/s, so ESD protection is crucial considering the potential impact of additional capacitance and inductance on high-speed differential pairs. Due to the reversible connector design, USB type C has higher ESD protection requirements.

In this case, the flow through design of the Comship DFN10P package simplifies PCB layout by placing the package at the high end, avoiding complex vias or loops, and saving PCB space. The recommended components for USB type C are listed in Table 3, and the recommended PCB layout is shown in Figure 6.

Part number VRWM IR (maximum) VC Cj ESD (contact) package CPDA10R5V0P-HF 5 V 50 nA 11 V 0.25 pF ± 14 KV DFN10P

4-wire/Bi CPDA10R5V0SP-HF 5 V 50 nA 12 V 0.15 pF ± 14 KV DFN10P

4-wire/Bi

Table 3: USB recommended components - C.

Figure 6: PCB layout diagram with recommended circulation design for USB type c.

Source: Electronic Design