I am trying to interface a 4-20mA two wire pressure transmitter ( loop powered ) to a USB data logger. The transmitter needs 9-32V excitation. I an trying to get this from the USB 5V dc and step it up to 15V with a Murata convertor (MEV3S0515SC).

The transmitter needs 5mA and so with 15V this will be 0.075W.

The covertor has about 80% efficiency and so the input power at 5V level will be 0.09W

ANd hence the power drawn from the USB port will be about 20mA. Is this calculation right or do I need to add some more power value for the convertor to work ?

If the above is correct , will this be OK to load the USB port ( I have no information how much my Sony notebook can source) ?

And do I need to filter noise when using such convertors ?

Thanks

Raghu