I’m trying to understand the nature of the VBUS pins on the DM8168 when the USB peripheral is used in host mode. The pins VDD_USBx_VBUS are listed in the terminal functions section of the datasheet as “USBx VBUS input (5 V). According to the Reference guide (SPRUGX8), page 2126, in host mode these pins are used to sense the VBUS line and check it is more than 4.4V to verify that the board is supplying power to the USB devices.
The DM8168 Datasheet electrical characteristics section doesn’t specify a separate abs max or operating range for the VBUS pins, so up until now I had assumed that the fall into the same category as the 3v3 pins. However, the evaluation board for the DM8168 connects these pins to the 5V_VBUS which agrees with the reference manual above.
Other TI parts with similar peripherals (e.g. AM3352) give abs max as -0.5 to 5.25V, but only give an operating range of 0v to 5v and don’t list the min and max voltages at which the comparator switches.
Could you please give some electrical specs for the VDD_USB1_VBUS and VDD_USB2_VBUS pins on the DM8168?
I would like to know Abs max, Vihmin and Vilmax specs and whether there are any restrictions on applying signals to these pins before the other power rails of the chip are stable.
Thanks
James
