Expected Voltage Drop on the Digital Output Lines of NI-651x Devices Hardware: Digital I/O (DIO)>>Isolated>>PCI-6517, Digital I/O (DIO)>>Isolated>>PXI-6513, Digital I/O (DIO)>>Isolated>>PCI-6512, Digital I/O (DIO)>>Isolated>>PXI-6514, Digital I/O (DIO)>>Isolated>>PXI-6515, Digital I/O (DIO)>>Isolated>>PXI-6512, Digital I/O (DIO)>>Isolated>>PCI-6514, Digital I/O (DIO)>>Isolated>>PCI-6519, Digital I/O (DIO)>>Isolated>>PCI-6516, Digital I/O (DIO)>>Isolated>>PCI-6515, Digital I/O (DIO)>>Isolated>>PCI-6518, Digital I/O (DIO)>>Isolated>>PCI-6513
Problem: I am using an NI-651x digital board, one of the 30 V bank isolated industrial devices. These devices require an external power supply for sourcing and sinking output signals. What kind of voltage drop can I expect between Vcc and PX.X for sourcing outputs or PX.X and Ground for sinking outputs? Solution: The NI-6512/6514/6516/6518 devices offer digital output lines for sourcing current. The following block diagram shows how the output line is switched and how to connect a load.
Notice that the connection between PX.X and Vcc is made by a Darlington Driver. This driver chip will introduce a voltage drop between its connecting terminals. The drop is not constant and is a function of the current being sourced. The voltage drop will not exceed the following specifications:
The NI-6513/6515/6517/6519 devices offer digital output lines for sinking current. The following block diagram shows how the output line is switched and how to connect a load.
Notice that the connection between PX.X and Ground is made by another Darlington Driver. This is a different chip but will also introduce a voltage drop between its connecting terminals based on the current being accepted. The voltage drop will not exceed the following specifications:
Related Links: Digital I/O Help for 6509/651x/6520/6521/6528 Devices(August 2005) Attachments:  - sinking_output.GIF - sourcing_output.GIF
Report Date: 04/09/2007 Last Updated: 04/11/2007 Document ID: 488H147E |
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