u-blox LARA-R2 series System Integration Manual

Also see for LARA-R2 series: System integration manual

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u-blox LARA-R2 series System Integration Manual Manual pdf 105 page image

LARA-R2 series - System Integration ManualUBX-16010573 - R02 Objective Specification Design-inPage 105 of 1482.6.2 USB interface2.6.2.1 Guidelines for USB circuit designThe USB_D+ and USB_D- lines carry the USB serial data and signaling. The lines are used in single ended modefor 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 theUSB 2.0 specification [9] are part of the module USB pins driver and do not need to be externally provided.The USB interface of the module is enabled only if a valid voltage is detected by the VUSB_DET input (see theLARA-R2 series Data Sheet [1]). Neither the USB interface, nor the whole module is supplied by the VUSB_DETinput: the VUSB_DET senses the USB supply voltage and absorbs few microamperes.Routing the USB pins to a connector, they will be externally accessible on the application device. According toEMC/ESD requirements of the application, an additional ESD protection device with very low capacitance shouldbe provided close to accessible point on the line connected to this pin, as described in Figure 56 and Table 43.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 bymounting a very low capacitance (i.e. less or equal to 1 pF) ESD protection (e.g. Tyco ElectronicsPESD0402-140 ESD protection device) on the lines connected to these pins, close to accessible points.The USB pins of the modules can be directly connected to the USB host application processor without additionalESD protections if they are not externally accessible or according to EMC/ESD requirements.LARA-R2 seriesD+D-GND29 USB_D+28 USB_D-GNDUSB DEVICECONNECTORD1 D2VBUSLARA-R2 seriesD+D-GND29 USB_D+28 USB_D-GNDUSB HOSTPROCESSORC117 VUSB_DETC117 VUSB_DETVBUSD3Figure 56: USB Interface application circuitsReference Description Part Number - ManufacturerC1 100 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R61A104KA01 - MurataD1, D2, D3 Very Low Capacitance ESD Protection PESD0402-140 - Tyco ElectronicsTable 43: Component for USB application circuitsIf the USB interface pins are not used, they can be left unconnected on the application board, but it isrecommended providing accessible test points directly connected to VUSB_DET, USB_D+, USB_D- pins.