Integration Manual

TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R04 Advance Information Design-in
Page 95 of 141
2.6 Data communication interfaces
2.6.1 Universal Serial Bus (USB)
2.6.1.1 Guidelines for USB circuit design
The USB_D+ and USB_D- lines carry the USB serial data and signaling. The lines are used in single ended mode
for full speed signaling handshake, as well as in differential mode for high speed signaling and data transfer.
USB pull-up or pull-down resistors and external series resistors on USB_D+ and USB_D- lines as required by the
USB 2.0 specification [6] are part of the module USB pin driver and do not need to be externally provided.
The additional VUSB_DET input pin can be optionally connected the USB VBUS supply (5.0 V typical) provided
by the host, to allow the complete bus detach functionality for further reduction of the current consumption: the
module disables the USB interface after a high-to-low logic level transition on the VUSB_DET input pin.
Routing the USB pins to a connector, they will be externally accessible on the application device. According to
EMC/ESD requirements of the application, an additional ESD protection device with very low capacitance should
be provided close to accessible point on the line connected to this pin, as described in Figure 48 and Table 32.
The USB interface pins ESD sensitivity rating is 1 kV (Human Body Model according to JESD22-A114F).
Higher protection level could be required if the lines are externally accessible and it can be achieved by
mounting a very low capacitance (i.e. less or equal to 1 pF) ESD protection (e.g. Tyco Electronics
PESD0402-140 ESD protection device) on the lines connected to these pins, close to accessible points.
The USB_D+ and USB_D- pins of the modules can be directly connected to the USB host application processor
without additional ESD protections if they are not externally accessible or according to EMC/ESD requirements.
D+
D-
GND
28
USB_D+
27
USB_D-
GND
USB DEVICE
CONNECTOR
VBUS
D+
D-
GND
28
USB_D+
27
USB_D-
GND
USB HOST
PROCESSOR
D+
D-
GND
38
USB_D+
36
USB_D-
GND
USB DEVICE
CONNECTOR
VBUS
TOBY-L2 series TOBY-L2 series
MPCI-L2 series MPCI-L2 series
D+
D-
GND
38
USB_D+
36
USB_D-
GND
USB HOST
PROCESSOR
VBUS
4
VUSB_DET
4
VUSB_DET
D1 D2
C1
D3
D1 D2
C1
Figure 48: USB Interface application circuits
Reference
Description
Part Number - Manufacturer
C1
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 - Murata
D1, D2, D3
Very Low Capacitance ESD Protection
PESD0402-140 - Tyco Electronics
Table 32: Component for USB application circuits