USB at 4,91 volt

[Tispe]

I am measuring 4.91 volts on my USB. Is this normal?

My hardware device consist of MCU and ICs. The IC's require 5 volts to operate. Some of the IC's are analog-to-digital converters. My ADC readings are off 0.02-0.5 volts then the actual measured value (I use two multimeters confirming).

When my ADCs are getting an input near the supply voltage the reading is off 0.5 volts. When the ADCs are getting an input of 1,5 volt my ADCs are off 0.02 volts.

I suspect the USB supply voltage is to blame.. How can I get a steady 5volts++ on my USB port? or get it from DC/DC...

[Jan Axelson]

Use a step-up voltage regulator.

The allowed voltage at the hub's downstream port can be as low as 4.75V for a high-power (500 mA) port or 4.4V for a low-power (100 mA) port.

Jan