PXIe-4154 Theory of Operation

The PXIe-4154 is a high-performance DC power supply designed specifically as a battery simulator for the test and development of RFIC power amplifiers, cellular telephones, mobile radios, and other portable battery operated devices.

The PXIe-4154 has two isolated channels that operate independently from one another:

  • Channel 0 is referred to as the battery simulator
  • Channel 1 is referred to as the charger simulator

Each channel has voltage and current control loops that work together through a linear regulation state to allow the channel to operate in either constant voltage more or constant current mode.

Both channels have sense terminals on the output connector. You can use them when remote sense is enabled in constant voltage mode to compensate for current-resistance loss drop due to cables and switches in the connection path from the channel to the load. If not optimal, the sense configuration and cabling of your measurement system can potentially degrade the load regulation of the channel.

Channel 0: Battery Simulator

When operating in constant voltage mode, channel 0 emulates a battery's response. It offers two transient response speeds so you can programmatically change the voltage control loop compensation circuit and optimize the transient response based on your test setup.

Transient response is important in many battery application because a fast response helps minimize the transient voltage dip that occurs due to large load changes, such as when a cell phone transitions from standby mode, where the phone consumes current in the order of hundreds of mA, to transmission mode, where it consumes current in the order of 2 A with peak currents as high as 3 A. Minimizing these dips prevents battery-operated DUTs from triggering low-voltage shutdown circuitry and interrupting any ongoing tests.

channel 0 also offers programmable output resistance. Using the positive range of the output resistance, you can emulate a battery’s internal resistance. Using the negative range, you can compensate for voltage drops that occur between the remote sense points and the DUT terminals. This feature is achieved by sensing the sourced current and feeding this measurement back to the voltage control loop so the output voltage level changes as a function of the sourced current based on the programmed output resistance value.

channel 0 also offers programmable output resistance. Using the positive range of the output resistance, you can emulate a battery’s internal resistance. Using the negative range, you can compensate for voltage drops that occur between the remote sense points and the DUT terminals. This feature is achieved by sensing the sourced current and feeding this measurement back to the voltage control loop so the output voltage level changes as a function of the sourced current based on the programmed output resistance value.

Channel 0 can sink up to 3.1 A continuously, which allows the channel to emulate a discharged rechargeable battery for testing battery chargers and battery charger control circuitry.

Channel 1: Charger Simulator

Channel 1 emulates the output of a battery charger. It has a fixed voltage control loop compensation, so its transient response speed cannot be adjusted, and it has limited sinking capabilities (typically 0.1 A).

This is the start of your concept.

PXIe-4154 Measurement Capabilities

The measurement circuits on each channel of the PXIe-4154 can simultaneously read the voltage and current at the output terminals (local sense) or sense terminals (remote sense).

These measurements are performed on each channel by two 16-bit ADCs—one for the voltage, and one for the current—that are synchronized at all times. Both converters run at a rate of 200 kS/s when continuously acquiring. You can average multiple samples to reduce the noise and increase the resolution of your measurements.

PXIe-4154 Channel Protection Features

Both channels of the PXIe-4154 offer overvoltage and inverse voltage protection.

The overvoltage protection monitors the voltage at the Output + terminal and disconnects the PXIe-4154 circuitry from its output connector pins when this voltage is 2.5 V above the voltage setpoint. You can programmatically enable/disable this overvoltage protection.

The inverse voltage protection monitors the voltage between the Output + and Output - terminals when in local sense, or between the Sense + and Sense - terminals when in remote sense, and disconnects the PXIe-4154 circuitry from its output connector pins when this voltage is less than -0.2 V. Inverse voltage protection is always active.

Sequence Engines

Each channel on the PXIe-4154 has a dedicated sequence engine, and therefore they can be treated as separate instruments using the NI-DCPower API. Channel 0 uses Engine0 and channel 1 uses Engine1. The sequence engines enable precise control over the sourcing functionality of the instrument and enable fast, deterministic timing. Additionally, you can utilize sequencing with the measurement functionality of an instrument to achieve specific measurement timing.

A sequence is a collection of setpoints that are executed one after another. A setpoint is a single output setting for a channel. When running a sequence, you can apply output values in succession (one setpoint followed by its corresponding source delay, immediately proceeded by the next setpoint) or you can use a trigger to configure the output at a precise time.

Additional options allow for multiple executions of the sequence, synchronizing the engine at various points within its execution, and so on.