VBUS supply current

[Dan Colob]

1. I am using a boost to power the USBD since I am using coin cell to power the whole system, what minimum and maximum supply current is needed/can be handled? 

2. What boost converter would you recommend

[ketiljo]

Not sure why you want to boost the voltage from a coin cell to power the VBUS pin. This is only needed of you're using the USB interface, and will get power from the USB host anyway

[Dan Colob]

Thats not the case for me, I will only be provided with a D+ and D- signal from an external chip that I need to connect here. Since the host is not providing the voltage, I need to figure that out myself os I am asking how I could use the coin cell. Is the USB draw the 2.4 mA listed on pg 569?

[ketiljo]

Yes, correct. 

Note that the nRF52850 us a USB device only and can not be a host.

[Dan Colob]

Sorry, I did not understand what you mean, I could feed the USB data I get into the 52840 and transmit it, right? SInce the external chip is not providing the voltage for the VNUS, that's all I need to make sure I have with a boost

[ketiljo]

Yes, the USB interface i bidirectional. But there's a difference between a host and a device. A host is usually a PC and is part of the link that initiates all communication on the bus. A device is the "slave", than can be a mouse, keyboard or whatever. A device can not communicate with another device, only a host. The nRF52840 can only be a device.

But if the chip you have can act as a host, all of good. You only need to boost the battery voltage to supply the VBUS pin.Just about anything goes here, there are tons of boost regulators around.