General

1. Are there CE / UL certificates for your devices?

Our devices do not come with a CE or UL certification. This is because our controllers are only ever components that the customer integrates into their system. There are a variety of applications and therefore different requirements concerning applicable directives. For example, the electromagnetic compatibility depends largely on the wiring, and this is application specific.
However, we have many customers who have successfully attained such certifications for their systems, which have our devices integrated inside.
You can find our certificates on the following page on our website: Certificates.

2. Why are my parameters not being saved?

Parameter changes are not permanently stored until saved to flash. How and when this happens can depend on device and firmware version, please refer to the documentation.

3. Why is the COM port inaccessible?

Check whether another application or instance of the Configuration/Service software is already using the port.

4. Which firmware version is compatible with my controller hardware version?

Compatibility information is documented in the software release notes of the device.

5. What is the input voltage I need for my setup?

Depends on controller model and required output voltage. Refer to the datasheet limits and ensure adequate margin for the required output voltage.

6. Is a defective unit covered by warranty?

Warranty coverage depends on warranty status and fault. Out-of-warranty units may incur repair and analysis charges.
See RMA

7. Can digital sensors (I²C/SPI) be connected directly to the controller?

Some devices expose pins that can be used to connect to such a sensor as part of a custom firmware project. Contact our support for inquiries.

8. What does a specific error code mean, and how can it be resolved?

The user manuals feature a chapter explaining the error codes. The required action depends on the specific error number.

9. How can the controller be remotely controlled?

Controllers support communication through the MeCom protocol over supported interfaces. APIs and protocol documentation are free of charge.

10. How should exported configuration files be interpreted?

Configuration files contain parameter values exported from the controller. They are intended to allow you to save and load your set of settings for your application. Values can be read in the file itself but that’s not the primary intended use.

11. Why should I use the sink temperature measurement?

The thermal modeling depends on heatsink temperature. You can set this to a fixed value if you have a stable heatsink (e.g. liquid-chilled plate), but incorrect assumptions about this can lead to unexpected thermal runaway. Having a heatsink temperature measurement will improve control and make validation easier.

12. What power supply and cable thickness is required for my setup?

This depends on the output current and voltage you need to cover in your application, the input voltage you wish to use and the efficiency of the device.

13. How should current limits, voltage limits, and ramps be configured?

Configure limits according to the load’s ratings and application requirements (whichever is stricter).

14. Where can I download the correct documentation, manuals, or application notes?

All files are available on the Meerstetter Engineering website (in the download page or in the specific product pages), including for older firmware or hardware versions.

15. What files or data does support need for proper diagnosis?

Typically: configuration file export, firmware version, software version, device type, serial number, screenshots, trace/log files, and a description of the issue.

16. How should a device be returned correctly with the RMA process?

Please contact support to do a pre-RMA diagnosis, open a case and obtain an RMA number, which will need to be written on the package.


TEC Controller & Peltier Elements

1. How do I connect my Peltier element to the TEC Controllers? (Wiring of the Peltier element)

Usually Peltier elements have a red (positive) and black (negative) cable connected. If you supply the Peltier element with positive current at the red cable, the cold side is the one with the marking of the manufacturer.

2. Is it possible to switch from heating to cooling and vice versa with a TEC Controllers, without changing the mechanical setup?

Yes, since the TEC Controllers have bipolar outputs they can switch between heating and cooling by changing the direction of the output current.

3. What does the hardware configuration NTC56K mean? I would like to use an NTC10K thermistor.

The NTC56K configuration means that the TEC controller can measure a maximum resistance of 56kΩ. Since NTC thermistors have a greater resistance at colder temperatures, this limits the minimum measurable temperature. For a typical NTC thermistor with 10kΩ@25°C this limit is reached at about -10°C. Please refer to the corresponding datasheet of the TEC Controller to learn more about the possible temperature ranges.

4. I ordered a TEC-1089-SV-PT100. Can I use NTC sensors?

The hardware configuration designator PT100 means that the controller's input circuitry is configured for Pt100 sensors. NTC sensors cannot be used with that configuration. If you would like to change the configuration, please contact us to return the TEC Controller.

5. TEC Measurement Input Sensitivity

The measurement input of the TEC Controller is very sensitive to external voltage, also to ground connections. Please make sure that the measurement connections are connected to a potential free thermistor and that they have no contact to an external voltage.

6. Does the TEC Controller have a built-in power supply?

No, an external power supply is needed to operate the TEC Controller. Please refer to the compendium for more information.

7. What is the maximum operating temperature of the TEC Controllers?

The components on the TEC Controller have a maximum allowed operation temperature of 85 °C. "Device Temperature" is measured between the power components and the base plate. The derating in the datasheet refers to this temperature and has a reserve of 10 °C.
"System Base Plate" refers to the heat sink or metal plate, where the TEC Controller is mounted on. As a rule of thumb, if the system base plate does not exceed 30 °C and if the controller is thermally and mechanically well fixed, then the "Device Temperature" reaches a temperature of 60 °C max.
Therefore, the TEC Controller can be operated at an ambient temperature of up to 85 °C and a cold system base plate (non-condensing).

8. Where are the temperature sensors connected to the TEC Controller?

The temperature sensors are connected to X7 (TEC Controller Setup Guide Page 9). More information here.

9. Is it possible to drive defined current shapes (temperature profiles) using scripting?

The TEC Controllers support scripting over the communication protocol. Every parameter can be set to a specific value using the commands SET_FLOAT and SET_INT. Please refer to the document TEC-Family MeCom Communication Protocol (PDF) to see all parameters. Another possibility is to define a lookup table which is then interpreted by the TEC Controller. Please refer to the TEC Application Note - Thermocycling.

10. Is it possible to drive multistage Peltier elements with the TEC Controllers?

Yes, this is possible from the TEC Controller Software v3.xx and higher without any adjustments.

11. Do you sell temperature sensors? Are there any sensors provided along with your TEC Controllers?

No, we do not sell temperature sensors nor are they included with our TEC Controllers. Please refer to our temperature sensors suggestions.

12. Do your TEC Controllers work with a PWM signal at the output? What about EMI?

Other TEC Controllers use the power input directly to generate a PWM signal for the Peltier element, which produces interferences and is not efficient. We generate direct current (DC) using switched-mode power supply (SMPS) instead, for ripple free output current and higher efficiency. More information on this topic.

13. What is the maximum power I should operate a Peltier element at?

When outlining the system, the current for the Peltier element should be between 0.3 and 0.7 times Imax. (Imax is given by the datasheet of the Peltier element.) More information about choosing the right Peltier element.

14. Is it possible to operate multiple Peltier elements in parallel or in series per channel?

Yes, this is possible. More information on this topic.

15. Is it possible to use two different temperature sensor configurations for a two-channel TEC Controller?

No, for both channels the same sensor configuration is used, which is defined in the hardware configuration upon ordering.

16. Is it possible to use Meerstetter TEC Controllers and Laser diode drivers with LabVIEW?

Yes, it is possible for TEC Controllers. You can download the LabVIEW VI TEC LabVIEW Control Software (ZIP). However, we don't support LabVIEW for Laser diode drivers.

17. Is it possible to use Meerstetter TEC Controllers and Laser diode drivers with Python?

Yes, it is possible. You can use a Python interface for the MeCom communication protocol to control and monitor Meerstetter TEC Controllers or Laser diode drivers. This package allows the remote control of multiple TEC Controllers or Laser diode drivers, for example by using a Raspberry Pi. More information and download on GitHub.

18. Is it possible to control Meerstetter TEC Controllers and Laser diode drivers via terminal commands?

Yes, the controllers and drivers can be used with e.g. HyperTerminal. Please refer to the Communication Protocol download section.

19. Do I need the a PC software to control the TEC Controller or Laser diode drivers?

Direct USB operation and MeCom communication require no PC software to be running. The TEC Controller resp. Laser diode driver will appear as a virtual COM port (USB Serial Port) on the PC. There is also the possibility to implement the communication using the RS485 protocol. More information about communication protocols.

20. Do you have 3D models / STEP files?

Yes, STEP files can be found in the download section.

21. Can I control Meerstetter devices with a Programmable Logic Controller (PLC)?

Yes, most PLCs will provide a way that makes it possible for it to communicate with our devices. Some PLCs may be able to make use of one of our API options (C/C++, C# .NET, Python) and others may offer the possibility of sending command strings directly to connected devices. For the latter option you can use our MeCom Command Tool web application to easily generate command strings that you can just copy and paste directly into your PLC control software.

22. Can several TEC Controllers be connected to one PC at the same time?

Yes, you can. To do this, connect the first device to your PC with the suitable USB cable and open the TEC Configuration Software or the TEC Service Software. To connect additional devices, repeat these steps for each device. Open the software for each device in a new window on your PC. The software now shows which device is connected to each of the open windows (in the TEC Configuration Software at the bottom of the status bar; in the TEC Service Software in the monitor tab)

The software can also be configured to only connect to a device with a specific address. The corresponding settings in the TEC Configuration Software are also described in the user manual of the software in the chapter «2.3.1.1 Addressing Specific TEC Controllers».

23. Why does my temperature reading show unrealistic or unstable values?

This may be caused by incorrect sensor wiring, sensor type, parameters, or intermittent contact.

24. Which temperature sensor type should be used (NTC, PT100, PT1000)?

This depends on the application requirements. For many applications, NTC is the choice that is easiest to implement at system-level and it provides good regulation performance.

25. How should PID parameters be tuned to avoid oscillation?

You can use the built-in autotuning function as the starting point.

26. Why does the output current or voltage of the TEC Controller stop before the limit I set?

In temperature control mode, the internal thermal model sets the output current and may stop before the limits if that’s the optimal choice. Alternatively, if either the voltage or the current limit is reached first, that will start limiting the other value as well.

27. How should the NTC calibration curve points be configured?

The temperature/resistance points should cover the intended operating range and match the sensor datasheet (which may provide them as a table or as a formula).

28. How should the coarse temperature ramp be configured?

You should choose a value that your thermal system is able to track and not faster than needed for your application, slower ramping can improve settling behaviour.


Laser Diode Drivers

1. Why does the laser driver measure current when no current is flowing?

Depending on the device, some reasons are possible that are within normal behaviour. A unipolar current measurement for large values might not be calibrated to measure accurately around 0A, thus showing a value that is close to it but not zero. Additionally, some pulse LDDs that work by chopping may only measure the current flowing internally, meaning they may show a measured current even during the pulse off phase.

2. What is a Laser Diode Driver?

A Laser Diode Driver (LDD) is an electronic current source designed to power laser diodes safely and repeatably. Unlike a generic voltage supply, an LDD regulates current, the key operating variable for laser diodes, so that optical output wavelength is stable and the diode is protected from transient and over-current events. Quality LDDs combine precise current regulation with protection, monitoring, and control interfaces so the laser can be integrated into a larger instrument or machine.

On the Meerstetter product line, LDDs are positioned as OEM current sources for CW, modulated, and QCW (and selected pulsed) operation, used across medical, spectroscopy, quantum, fiber-communication, and other high-tech applications. They emphasize stable output current, temperature stability, versatile interfaces, and quick system integration supported by free configuration software.

At a high level, an LDD typically provides:

  • Programmable constant current (and often constant optical power via a monitor photodiode feedback).
  • Closed-loop regulation with fast control to keep current at setpoint under supply/load variations.
  • Safety features such as current limits, interlock, fault monitoring, and fast shutoff to protect the diode.
  • Interfaces (e.g., USB, RS-485, CAN on Meerstetter models) and firmware features for configuration and automation.

Meerstetter's portfolio ranges from low-power modules (e.g., LDD-1321, 0-1.5 A / 0-14 V) to high-power modules (e.g., LDD-1303 up to 0-20 A / 1-120 V).

3. How does a Laser Diode Driver work?

Principle: An LDD implements a closed-loop current regulation architecture. The driver measures output current through a precision sense element, compares it to the commanded setpoint, and then changes the compliance voltage (output voltage) to minimize the error. The power is delivered by a switching power stage (in some designs also a linear stage to minimize noise). This yields a stable, low-ripple current into the diode over dynamic operating conditions.

Power-conversion topology: Modern high-power LDDs typically employ efficient switch-mode stages. For instance, Meerstetter's LDD-1303 uses a buck-boost topology, enabling compliance voltages below, equal to, or above the input supply. This allows the LDD-1303 to drive up to 120 V compliance from a single 48 V supply (up to 60 V supply possible). This is useful when a single driver must accommodate a variety of diodes or diode strings.

Operating modes:

  • Constant Current (CC): The driver regulates current to the programmed value; optical output follows the laser's L-I (Light vs Current Intensity) behavior.
  • Constant Optical Power (CP): With a monitor photodiode, the driver adjusts current to maintain a set optical power instead of electrical power (within the driver’s current limits).
  • CW, modulated, QCW/pulsed: Meerstetter's product family supports continuous operation and controlled modulation/pulsing (within each model's timing limits and rise/fall capabilities).

Control and integration: Meerstetter devices expose digital interfaces (e.g., USB, RS-232, RS-485) and free PC software for configuration and monitoring, making it straightforward to embed drivers into instruments and production equipment. Once configured, the devices can run standalone without any interaction required.

Protection: LDDs enforce current limits, handle faults (e.g., over-temperature, open load), and provide interlock and temperature inputs for the diode assembly. For example, the LDD-1303 includes two laser-diode temperature inputs and integrated safety functions; its digital control firmware is upgradeable.

4. What issues do Laser Diode Drivers address?

Laser diodes are fragile optoelectronic components. An LDD mitigates the following challenges:

  • Over-current and transient protection: Prevents destructive inrush, overshoot, or spikes at start-up and during modulation; enforces hard/soft current limits and interlocks.
  • Stable optical output: Maintains a steady drive current so output power and wavelength remain consistent over time.
  • Thermal/load variability: Compensates for changes in laser forward voltage and ambient conditions so that the electrical operating point remains within safe limits.
  • Application-level control: Enables precise laser output control through analog or digital modulation (CW, QCW, or pulsed), ensuring the required optical power, pulse shape, and timing for application-specific operation.
  • System integration and serviceability: Digital telemetry (current, voltage, status, temperatures) and PC tools simplify set-up, diagnostics, and field updates.

Bottom line: Using a dedicated LDD maximizes laser uptime and longevity, improves measurement/process repeatability, and shortens integration time compared to ad-hoc or generic supplies.

5. What are the typical applications of Laser Diode Drivers?

Meerstetter highlights deployment in medicine, spectroscopy, quantum applications, fiber communication, and more, reflecting the breadth of use cases that need precise current control and robust protection.

Representative application families include:

  • Medical and life sciences
    • Dermatology/therapy sources requiring controlled dose delivery.
    • Ophthalmic and surgical modules where safety interlocks and repeatability are mandatory.
    • Bio-instrumentation (e.g., flow cytometry, fluorescence excitation) that benefits from low noise and power stabilization.
  • Scientific instruments & metrology
    • Spectroscopy setups (gas, Raman, absorption) where drive current stability translates to measurement stability.
    • Interferometry and precision reference sources needing drift-minimized operation during long runs.
  • Quantum/advanced research
    • Cooling/trapping beams and atom optics requiring quiet CW currents or carefully shaped pulses for experiments.
  • Fiber-optic communications
    • DFB/FP lasers driven in CC or CP mode for transmitter stability; bias control plus high-speed external modulation where applicable.
  • Industrial processing & manufacturing
    • Material processing (marking, micro-machining) using high-power diode stacks or fiber-coupled modules.
    • Inspection, alignment, and machine-vision lighting with controlled intensity and rapid enable/disable.
  • Sensing, ranging, and LIDAR
    • Pulsed/QCW operation with controlled pulse trains and system interlocks for eye-safety and reliability.

6. What types of Laser Diode Drivers exist, and how do they differ?

There are multiple ways to classify LDDs. The distinctions below help with selection and system architecture.

A) By regulation topology

  • Switch-mode (SMPS) drivers
    • Use high-efficiency switching conversion with output filtering.
    • Benefits: high power density, broad current/voltage capability, lower thermal load.
    • Modern Meerstetter high-power models are switch-mode, e.g., the LDD-1303 with buck-boost conversion for flexible compliance relative to input.
    • Tradeoffs include EMI considerations (mitigated by proper layout and filters).
  • Linear drivers
    • Use a linear pass element for minimal spectral noise at the expense of efficiency.
    • Best for low-power, ultra-low-noise niches.
    • If a linear LDD is required, verify model-specific availability.

B) By control mode

  • Constant Current (CC)
    • The driver holds the current at the setpoint.
    • Optical power follows device characteristics and temperature.
    • This is the universal default in LDD operation.
  • Constant Power (CP)
    • With a monitor photodiode, the driver regulates optical power by adjusting current in closed loop.
    • Maximum current limits remain enforced.
    • Useful when output intensity stability matters more than a fixed current.
    • Meerstetter offers LPC (Light Power Control) options, depending on model availability.

C) By operating regime

  • CW (continuous wave)
    • Long-duration, steady operation.
    • Core requirement is current stability and thermal management.
  • Modulated/QCW/pulsed
    • Drivers support time-varying current, from slow analog dimming to microsecond-class pulses.
    • LDD-1303 provides internal signal generators for modulation and pulse features.
    • LDD-1125 explicitly supports CW, QCW, and pulsed modes.
    • Always verify pulse width, rise/fall time, and duty-cycle limits.

D) By power class

  • Low-power modules
    • Smaller current/voltage range for compact instruments.
    • Example: LDD-1321.
  • High-power modules
    • High current and/or high compliance voltage for diode bars and diode strings.
    • Examples: LDD-1137 and LDD-1303.

E) By form factor

  • OEM Modules
    • Compact, integration-ready drivers designed to be embedded into larger systems.
    • Operate with external DC supplies and require appropriate cooling.
    • Provide digital communication interfaces and PC software for setup.
    • All Meerstetter units presented on the product page fall under this category.
  • Benchtop Drivers
    • Standalone instruments with integrated user interfaces, monitoring, and configuration features.
    • Intended for laboratory use, prototyping, testing, and characterization.

7. Which electrical parameters are crucial when selecting a Laser Diode Driver?

Device selection is an exercise in matching electrical, thermal, safety, and integration requirements. The following parameters are the core checklist.

A) Output capability and compliance

  • Maximum output current
    • Must exceed the laser's required operating and peak/QCW current with margin.
    • An overview of the available output capabilities can be found on the LDD product page.
  • Compliance voltage (max output voltage)
    • Must exceed diode forward voltage (or series string sum) plus cabling losses.
    • If your application has varying or high compliance requirements, a buck-boost driver such as the LDD-1303 can source up to 120 V compliance from a 48 V supply.
  • Output power envelope
    • The product of laser current and compliance voltage dictates the electrical power delivered to the load.
    • Higher output currents require larger wire diameters and additional thermal considerations.

B) Input supply and power architecture

  • DC input range
    • Verify compatibility with the available supply voltage.
    • Models supporting 48 V DC operation can be powered directly from standard industrial supplies.
  • Supply vs. compliance voltage planning
    • Ensure sufficient input headroom when using buck-only drivers.
    • Alternatively, leverage buck-boost technology (e.g., LDD-1303) for additional flexibility.

C) Control behavior and timing

  • CW stability and resolution
    • Define the required output current resolution and acceptable ripple.
    • Verify compliance with the required stability specifications.
  • Modulation/QCW/pulse capability
    • Verify minimum/maximum pulse width, rise/fall time, and repetition-rate limits.
    • For embedded waveform generation, consider devices with internal signal generators or dedicated pulse support.
  • Light power control (LPC) option
    • If optical power regulation is required, verify availability of the LPC option.
    • Ensure compatibility with the selected monitor photodiode and feedback circuitry.

D) Protections, monitoring, and laser safety

  • Hardware and software current limits
    • Configurable limits help prevent accidental over-drive conditions.
  • Interlock and enable logic
    • Verify compatibility with machine safety requirements, including door switches, shutters, and readiness signals.
  • Temperature monitoring
    • Check availability of temperature sensor inputs as needed.
    • Can be used to implement over-temperature warnings and automatic shutdown functions.
  • Fault handling and safe shutdown
    • Confirm driver behavior on open-load, short-circuit, bus-voltage, or over-temperature fault conditions.
    • Important characteristics include fast current cut-off, fault latching, and status reporting.

E) Interfaces and software

  • Digital control and telemetry
    • Verify support for the required communication interfaces.
    • USB and RS-485 are common on Meerstetter LDDs.
    • PC software simplifies setup, monitoring, logging, and maintenance.
  • Analog I/O
    • Verify availability of analog setpoint inputs and monitoring outputs if required by the system architecture.

F) Mechanical, thermal, and integration details

  • Form factor and cooling
    • Verify that the driver dimensions fit the available installation space.
    • Ensure adequate heatsinking and airflow for worst-case operating conditions.
  • Wiring and EMI/ESD practice
    • Keep laser-diode wiring as short as possible.
    • Consult the product documentation for pin assignments and grounding concepts.
    • Verify compatibility with chassis-ground and protective-earth requirements.