lpcware

LPC4357: Problem with USB0 in DFU mode

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by boscfab on Fri Nov 15 02:57:17 MST 2013
Hello ,
I'm trying to run my card with LPC4357 in BOOT mode for programming in DFU mode.
In my card I applied "exactly" the recommendations outlined in the document AN11392 (fig2) for USB0_VBUS, but when I turn on my card , the voltage on this pin drops to 0.4 V.
I tried to remove the 24k resistor .
I turned on the board in BOOT mode DFU , I connected the USB cable to the PC and then I connected an ammeter to measure the current that absorbs USB0_VBUS pin of the MCU.
In this sequence the DFU mode works correctly and I measured a current of about 3.4 mA which is absorbed by only the pin USB0_VBUS.
By this measure I think that the solution contained in the document AN11392 ( fig2 ) for USB0_VBUS is not correct.

I searched on the MCU data sheet but I have not found any indication of the minimum operating current of the pin USB0_VBUS .......

Does anyone have any suggestions on what I can do to fix this?
I have to use port USB0 only in Device mode .

Thank you,

Fabio

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