topic Re: LPC18xx USB0_ID Pull up resistor value in LPC Microcontrollers

LPC18xx USB0_ID Pull up resistor value

lpcware — Wed, 15 Jun 2016 18:17:17 GMT

Content originally posted in LPCWare by nallison on Sun Nov 29 17:51:49 MST 2015
Hello,

We're using the LPC1830 and our test engineer wants to know the value of the internal pull-up resistor on the USB0_ID pin. Refer e.g. UM10430, Table 170, page 325 where it says:

Quote:
USB0_ID
Indicates to the transceiver whether connected as an A-device
(USB0_ID LOW) or B-device (USB0_ID HIGH). For use with
OTG, this pin has an internal pull-up resistor

I have looked through the datasheet and user manual but found no numerical value for this pull-up resistor. A brief search of the USB IF spec documents did not give me any data either.

Please direct me to the documentation that specifies the pull-up value for the LPC1830.

Thank you
Neil

Re: LPC18xx USB0_ID Pull up resistor value

lpcware — Wed, 15 Jun 2016 18:17:18 GMT

Content originally posted in LPCWare by MikeSimmonds on Sun Nov 29 21:31:28 MST 2015
As a generalisation to the OP's question, is there any technique to physically measure this and other unspecified values?
NB: I am not a hardware engineer.

EDIT: Or to calculate the desired value from other known values and/or measurements?

Mike.

Re: LPC18xx USB0_ID Pull up resistor value

lpcware — Wed, 15 Jun 2016 18:17:19 GMT

Content originally posted in LPCWare by lpcmunich on Wed Dec 02 09:31:12 MST 2015
Hi Guys,
In general, these pull-ups are not passive resistors but active current sources.
Typically delivers around 50µA when enabled, refer Ipu vs Vi characteristics in the data sheet (Electrical pin characteristics).