PXIe-4154 Sourcing and Sinking Details

Because the PXIe-4154 is designed as a battery simulator, it has unique output behavior relative to other NI-DCPower instruments.

PXIe-4154 Maximum Overall Current Sourcing

The maximum cross-channel current that the PXIe-4154 can source from both channels combined is 3.1 A. Thus, the sum of the current setpoints for each channel (current limits when in constant current mode) must be ≤3.1 A.

This limit also applies if both channels are programmed with sequences in separate sessions; the sum of the maximum current setpoint from each sequence must also be ≤3.1 A.

This limitation is due to the maximum allowable current that can be drawn from the chassis. If the sum of the setpoints is >3.1 A, a software error occurs, regardless of how much current is actually flowing out of the channels.

These limitations do not apply if channel 0 is sinking current. Channel 0 can sink up to 3.1 A while channel 1 is sourcing its maximum rated current. The current sink limit is not programmable in either channel; the current setpoint only programs the current source limit. When using the channels in this configuration, set the current setpoint of channel 0 to a value less than 1.6 A.

You can then set the setpoint of channel 1 to the maximum current setpoint of 1.5 A, which results in the setpoint combination totaling less than 3.1 A. Refer to PXIe-4154 Sinking Details for more information.

PXIe-4154 Sinking Details

The two channels of the PXIe-4154 have disparate sinking capabilities.

  • Channel 0 (battery simulator) can sink up to 3.1 A continuously in the 3 A range and up to 31 mA continuously in the 30 mA range. Channel 0 can be used to emulate a discharged battery for testing battery chargers and battery charger control circuitry.
  • Channel 1 (charger simulator) has limited sink capabilities (0.1 A typical).

The current setpoint for both channels is fixed when sinking and cannot be changed programmatically, so the current limit in constant voltage mode and current level when in constant current mode only applies to currents being sourced.

Note To source maximum current on channel 1 while sinking on channel 0, program the current limit or current level of channel 0 to 1.6 A or less. Refer to the PXIe-4154 Output Current topic for more information.

PXIe-4154 Channel 0 Sink Derating

The maximum sink current while channel 0 remains in constant voltage mode derates linearly from -3.1 A in specific conditions.

This derating behavior occurs when all of the following conditions are met:

  • Channel 0 is sinking;
  • The voltage between the Output HI and Output LO terminals <1.2 V; and
  • The channel is configured for remote sense and the sense terminals are externally connected to their respective output terminals.

Refer to the following figure.

Figure 6. PXIe-4154 Quadrant Diagrams


If the programmed voltage setpoint for channel 0 is changed to a lower value than 1.2 V while sinking 3.1 A, the channel sinks the current but the output voltage is clamped to 1.2 V and the channel no longer maintains the output voltage at the programmed voltage setpoint.

If the remote sense leads are connected at a distant load, the voltage drops on the leads that connect the Output HI and Output LO terminals to the load due to the current flowing. The derating of the sink current shown in the figure starts when the voltage between the Output HI and Output LO terminals drops below 1.2 V, but, due to the voltage drop in the leads, this results in a voltage larger than 1.2 V at the load.

If the sunk current exceeds 3.1 A, the channel will operate in constant current mode.