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Model 52400 Series High Precision Source Measure Unit
Key Features
  • Hybrid compatible PXI
  • Four quadrant operation
  • High source/measurement resolution
    (multiple ranges)
  • Low output noise
  • High measurement speed (100k s/S)
  • High output slew rate
  • Optional measurement log
  • DIO/Trigger bits
  • Output profiling by hardware sequencer
  • Programmable output resistance
  • Floating & Guarding output
  • 16 Control Bandwidth Selection
  • Master / Slave operation
  • Driver with LabView/LabWindows & C/C# API
  • Softpanel GUI

Data Sheet

Chroma 52411 Dual Independent & Isolated Source Measure Unit
Product Details


  • Semiconductor Test
  • LED / Laser Diode Test
  • Battery Test
  • Transistor Test
  • Solar Cell Test
  • Electric Vehicle Test
  • Avionics Test
  • Power Electronics Test
  • Sensor Test


The Chroma 52400 series is a hybrid compatible PXI based SMU (Source Measurement Unit) card which can be used in both PXI and PXIe chassis. It is designed for highly accurate source or load simulation with precision voltage and current measurements.

SMU combines four-quadrant-source with precision and high speed measurement. This unique capability makes a SMU the ideal instrument in many parametric test applications ranging from ICs, two-leaded components such as sensors, LEDs, laser diodes, transistors, to solar cells, batteries and many other electronic devices.

To meet various test requirements, the 52400 series has 16 control bandwidths allowing user selection of a stable operation, multi-ranges combined with 18 bit DAC/ADC to provide the best programming and measurement resolution and accuracy available at a sampling rate of up to 100k s/S. Special programmable output resistance allows users to set as internal series resistance of a battery making Chroma 52400 series SMU an ideal tool acting as a battery simulator.

±force, ±sense and ±guards lines are standard to avoid leakage current and reduce settling time, especially for the mobile IC and Sensor test applications requiring very low current.

The 52400 series has a patented hardware sequence engine that uses deterministic timing to control each SMU. This sequencer comes with built-in 32k readings storage memory, allowing for cross module/card synchronization and latency free output control and measurement. This measurement is possible as no PC communication is required during a test process.

The C, C#, LabView, LabWindows APIs plus versatile soft front panels are offered as standard accessories. The back connectors are compatible with both PXI and PXIe chassis. All of these features enable easy integration to PXI or PXIe systems designed for any application.



All Chroma 52400 series SMUs are designed for four quadrant operation for use by applications that require voltage/current source or load simulation. During a load operation, the module is limited by the PXI chassis' standard of 20W heat dissipation per slot. This limit is noted as the imbalance in the quadrant diagrams for higher power models.

The diagram below shows the quadrants of all Chroma 52400 SMU series.

52400 quadrant diagram



SMU output waveformTo reduce test times, Chroma's SMUs are designed for fast response providing a high speed output voltage and current. The impedance of the DUT, the fixture and/or cabling may potentially cause the entire control loop instability under voltage or current output mode. An unstable loop may cause saturation, oscillation, or even damage the DUT. As a result, the user may be required to add a capacitor or an inductor on the test fixture to regain stability of the system.

The 52400 series SMUs provide 16 user selectable control bandwidths eliminating the need for additional physical capacitors or inductors strategically placed at the DUT. The Chroma Bandwidth selection can be part of the test parameters in a test script where the value can be adjusted to accommodate the DUT.



hardware sequencerThe Chroma Hardware Sequencer is a powerful tool that can predefine commands as instrument executable steps. This allows latency free control and measurement since no PC interaction is required during execution. The sequence optimizes the module's performance for applications like semiconductor test where speed and timing control are critical.

In this mode, once the instrument receives the start trigger, it will execute the commands in the sequencer table line by line or as defined upon trigger. Screen capture shown on the right is an example of a sequence profile setting by using Soft Front Panel provided by Chroma.



Guarding is an important technique for very-low current measurements. Guarding reduces Leakage Current error and decreases Settling Time. It keeps the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. It also eliminates the cable capacitance between source measure unit (SMU) and DUT for faster and more accurate measurements.

Guarding for low current applications



Master/Slave operationFor maximum flexibility, Chroma 52400 series SMUs allow Master/Slave operation when higher current under FVMI mode is required. To ensure accurate current sharing between modules, and maximum performance, Chroma SMUs allow only similar models paralleled for higher current/ power.

Current sharing is achieved by one channel operating as the Master under FVMI mode while the Slaves operate in FIMV mode. The Master channel is programmed in voltage mode while the Slaves are set to current mode. The Slaves will follow the Master's set voltage.

The figure to the right displays a blocked diagram for parallel configuration.



Soft PanelTo integrate the 52400 series SMU systems, a versatile Soft Front Panel is provided as a standard accessory which allows users to conduct verification test or debugging. This Soft Front Panel provides GUI to set the SMU output mode, range and level. The measured voltage or current reading will be shown after output is turned on. For modules that have duel output channels, both channels can be controlled by the same soft front panel.

This Soft Front Panel also includes the control for hardware sequence setting described above. Users can save unlimited predefined profiles to the PC which can be recalled later for varying applications.



Application Notes
Application Note   Using a Source Measure Unit as a Device Power Supply for Semiconductor Testing

This document is going to explain why Source Measure Unit (SMU) is an ideal Device Power Supply (DPS) for semiconductors testing.

SMUs are optimized for both speed and precision, repeatability, and they offer faster rise time and much lower measurement uncertainty than typical power supplies. Due to the combination of source and measurement into a single unit, many advantages are found during semiconductor testing. The high level of integration and remarkable flexibility make the SMUs ideal and economical for semiconductor testing.


Application Note   Optimal SMU Response by Large Selectable Control Bandwidths for Capacitive Loads

Typically, SMUs are considered the user’s DUT as part of the control loop. It is difficult for the designer to guess what exact load a user will need to measure. Some capacitive loads can cause ringing in the transient response of the device and make the system unstable.

The “Optimized Control Bandwidth” offers much better settling times with no overshoot. It therefore provides the SMU output an optimized response.

Chroma SMUs provide 16-step programmable slew rate. Users can select the control loop for optimal SMU responses to electrical loads and obtain an ideal response with minimum rise times and without overshoot or oscillations.


Application Note   Guarding : Guard Shield Used For Low Current (nano-Amp) Measurement

Guarding - A technique that reduces leakage current errors and decreases response time. It keeps the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. It also eliminates the cable capacitance between source measure unit (SMU) and DUT for faster and accurate measurements. 

A guard is a low-impedance point in the circuit that’s at the same potential as the high-impedance lead in the circuit. In a guarded measurement, because the shield is driven to the same potential as the force high terminal of the SMU (Source Measure Unit), no current flows through the insulation medium; therefore, eliminates leakage current effects.


Application Note   Guarding: Enhance DC Transmission Speed for Very Low-current Measurement

Guarding - A technique that reduces leakage current error and decreases settling time. It keeps the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. It also eliminates the cable capacitance between source measure unit (SMU) and DUT for faster and accurate measurements. This document describes how to reduce settling time for very-low current measurement. 




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