VBUS design USB OTG

Apr 29, 2010 1 Replies

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Mahen K 16 years ago

The schematic below is from ISP150x application note. The OTG application uses external charge pump to source 5V@100ma in the host mode. If the OTG application role is changed from Host to Device/ Peripheral powered from the connected USB Host, the VBUS line receives

5V from the host. The charge pump is in disabled state but since its output is connected directly to the VBUS on which we have 5V supplied by the host will it not cause any damage to the charge pump IC? Any suggestions or reference schematic for interfacing external charge pump with OTG controllers.

Schematic :

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Full Application note :

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Thanks

-Mahen J

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Michael Karas 16 years ago

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Seems that you would have to look closely at how the charge pump IC works. The data sheet for the part you are using should shed some light on the characteristics of the part and whether the output of the part is susceptible to back feed when it is disabled.

- mkaras

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