Minimum Current Specification For The PXIe-4330

Updated Jul 12, 2018

Reported In

Hardware

  • PXIe-4330

Issue Details

I am looking through the PXIe-4330 manual and I noticed that it states there is a minimum current value of 29mA set for the device. Does this mean the device can't source less that the 29mA stated?

Solution

No, this is the minimum guaranteed amount of current the device will source. If the impedance of the output circuit requires for a current less than 29mA to be sourced, this is the amount of current that will be sourced from the device. However, if the impedance of the output circuitry causes the current draw to be larger than the current that the power supply of the device can source, the device will automatically lower the output voltage in order to guarantee the 29mA minimum current is sourced.

Example:

Given Ohm's law: V = IR
Where V the voltage output from the PXIe-4330, I the output current and R the equivalent resistance of the output circuitry.

For a value of 1kΩ for R and 10V for V, the required current will be 10mA and that is the amount of current that will be sourced.

For a value of 100Ω for R and 10V for V, the required current will be 100mA. If the power supply is not able to source 100mA it will reduce the voltage, so that at least 29mA are sourced, so the output voltage can be reduced to up to 2.9V, in order to guarantee the 29mA current are supplied.

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