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OSD3358-SM-RED
– User Guide
Rev. 1.0 9/19/2017
Octavo Systems LLC
Copyright 2017
4.14
4 port Evaluation board USB host
Figure 54: OSD3358-SM-RED USB host hub circuit
Figure 54 shows the 4 port USB hub U8, 4 USB ports part of X4 and X5 connectors and a
power distribution switch U15 that combine to form the USB host interface for the OSD3358-
SM-RED Board. The USB hub chip converts USB1 interface of the processor into 4
independent USB connection ports each of which have ESD protection and can be used to
connect USB peripherals simultaneously. The hub chip has UART and I2C interfaces which can
be used to configure it. Battery charging is disabled on all the ports because of the 500mA limit
that can be supplied from U15. A 24 MHz crystal is used to supply clock to the hub controller
USB2534 (U8) that is powered by SYS_VDD1_3P3V. The four ports can be used
simultaneously, however the combination of the attached peripherals cannot exceed the 500mA
current draw limit.
