Usb 2.0 Signal Descriptions; Signal Groups; Overcurrent Protection - Intel Quark SoC X1000 Design Manual

5.2

USB 2.0 Signal Descriptions

5.2.1

Signal Groups

Table 21. Signal Groups
Group
DATA
OVERCURRENT
POWER_EN
Note: The connectors must meet the USB2.0 Connector Specification.
5.2.2

Overcurrent Protection

®
Intel Quark™ SoC X1000 has implemented two USB overcurrent signals. The 2
overcurrent pins are connected to the two host USB 2.0 ports. Each of the OC pins
needs to be connected to an external over current protection circuit, see
an example. Each USB port may draw up to 500 mA. The overcurrent protection
circuitry needs to be able to support at least 2 A to ensure proper functionality of USB
compliant devices. However, if a fault device is plugged into the USB port it should
trigger an overcurrent when current drawn is more than 500 mA. Designer must
balance between optimum cost and protection level.
When the current rating of the protection circuit has been decided, it is crucial to
ensure that the overcurrent layout is designed to support the amount of current
expected. For example when the overcurrent circuit is designed to support up to 2A the
overcurrent trace layout should be using a big fat trace or plane that can sustain at
least 2A of current. Failure to design the trace to support high current may cause the
trace on motherboard to burn out and cause permanent damage to the protection
circuit. The overcurrent signals require a pull-up to the 3.3 V Suspend Rail with 8.2 k
to 10 k resistor.
®
Intel Quark™ SoC X1000
PDG
48
®
Intel Quark™ SoC X1000—Universal Serial Bus 2.0 Design Guidelines
Signal Name
USBH0_DP, USBH0_DN
USBH1_DP, USBH1_DN Universal Serial Bus Port Differential Pairs
USBD_DP, USBD_DN
USBH0_OC_B
Overcurrent Indicators
USBH1_OC_B
USBH0_PWR_EN
Power Enables to Platform Regulators
USBH1_PWR_EN
Description
Figure 25
June 2014
Order Number: 330258-002US
for