EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Freshman on May 29, 2024, 12:09:02 pm
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In this device checklist link: https://ww1.microchip.com/downloads...lateral/SchematicChecklistUSB2512BQFNRevA.pdf
I see there are three different modes of configuring the VBUS_DET pin.
My questions are :
1. Does the self-powered, bus-powered, etc.. mean that the "Hub" is being self-powered or bus-powered? Or does it mean the "device" connected is self powered or bus powered?
2. What is the purpose of VBUS_DET pin and what advantages are there in each configuration mode?
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1. This is obviously for the hub side. The diagrams don't even include the device ports.
2. In the bus powered VBUS_DET is used to detect the actual bus voltage via a resistive divider. In the self powered mode it is just connected to the common 3.3V supply.
The first case is when you use this as a regular hub with a USB connector on the host side. The second case is when you connect this hub to an MCU on the same board, for example. In this case there is not really a VBUS between the MCU and the hub.
The device side VBUS is completely separate from any of this.