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Effect of Merging Channels on Other Functions and Properties

Last Modified: December 3, 2020

When you merge channels of an SMU, the normal values you can specify or behaviors for certain functions and properties change accordingly.

Merging channels affects the following aspects of programming with NI-DCPower.

  • Setting current limits—For relevant functions or properties that control current, maximum current you can source increases as follows:
    Without Merged Channels With Merged Channels
    Per-Channel Maximum Per-Channel Maximum × Merge Count
    spd-note-note
    Note  

    The Current Limit Autorange and Current Level Autorange properties also account for the increased current values you can specify when channels are merged.

  • Setting programmable output resistance—Output function–dependent.

    With DC Voltage, output resistance range decreases as follows.

    With DC Current, output resistance range expands as follows.

    Output Function Without Merged Channels With Merged Channels
    DC Voltage Valid Range Valid Range / Merge Count
    DC Current Output resistance <0 Ω (-∞, Upper Negative Limit] (-∞, Upper Negative Limit / Merge Count]
    Output resistance >0 Ω [Lower Positive Limit, +∞) [Lower Positive Limit / Merge Count, +∞)
  • Operating in compliance—In addition to the normal criteria for operating in compliance, merged channels may operate in compliance when their outputs are poorly balanced, such as when one of the channels being merged is physically disconnected.

    The Query In Compliance function reports whether a channel is operating in compliance.

  • Requesting power output—Maximum power you can request from the instrument with the Requested Power Allocation property increases as follows:
    Without Merged Channels With Merged Channels
    Per-Channel Maximum Per-Channel Maximum × Merge Count
    spd-note-note
    Note  

    When merging channels, it is possible to request more DC output power with this property than the SMU can provide across all channels. In this event, the SMU does not source the requested power and NI-DCPower returns an error.


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