ILX Lightwave LDT-5910B 4 A 16 W Precision Thermoelectric Temperature Controller

ILX Lightwave LDT-5910B Precision Thermoelectric Temperature Controller

The ILX Lightwave LDT-5910B is a microprocessor-based precision thermoelectric temperature controller designed for laser diodes, optical detectors, electronic components, and other temperature-sensitive devices. It combines high analog stability with configurable sensor support and a bipolar thermoelectric output capable of both heating and cooling.

This particular LDT-5910B does not include the optional ILX Lightwave Model 1233 GPIB/IEEE-488.2 interface. Operation is performed locally through the instrument’s front-panel controls and large green LED display. The absence of the optional interface makes this configuration suitable for benchtop applications that do not require remote computer control.

The controller supplies up to 4 A of thermoelectric current and 16 W of typical output power. It supports compatible two-wire NTC thermistors, AD590 current-output temperature sensors, and LM335 voltage-output temperature sensors. Thermistor operation includes user-selectable 10 µA and 100 µA sensing currents for compatibility with a broad range of sensor resistances.

Typical applications include laser diode testing, laser frequency and wavelength stabilization, infrared detector cooling, temperature-dependent electronic device characterization, optical component evaluation, photonics research, and controlled laboratory experiments.

Features and Benefits of the ILX Lightwave LDT-5910B

• Precision temperature control: Provides stable thermal regulation for laser diodes, detectors, electronic devices, and related laboratory components.
• Bipolar TEC output: Supplies current in either direction for controlled heating and cooling.
• 4 A maximum output: Supports compatible thermoelectric modules requiring up to 4 A of drive current.
• 16 W typical output power: Provides practical temperature-control capacity for laser diode mounts and other supported thermal loads.
• High thermal stability: Offers short-term stability of 0.005 °C or better and long-term stability of 0.01 °C or better under the documented conditions.
• Multiple sensor types: Supports compatible two-wire thermistors, AD590 current-output sensors, and LM335 voltage-output sensors.
• Wide thermistor resistance range: Accommodates compatible thermistors from approximately 25 O to 450 kO.
• Selectable thermistor sensing current: Provides 10 µA and 100 µA settings for different resistance ranges and measurement requirements.
• Adjustable current limit: Helps protect the connected thermoelectric cooler from excessive drive current.
• Temperature limits: Supports configurable upper and lower temperature boundaries for controlled device operation.
• Closed-case calibration: Allows calibration without opening the instrument enclosure.
• Automatic parameter storage: Recalls the previous operating configuration after power is restored.
• Optional external booster support: Can operate with compatible booster hardware when output requirements exceed the internal controller capacity.
• Local front-panel control: This no-GPIB configuration provides direct manual operation without requiring a computer or automation interface.

Laser Diode Temperature Control

Laser diode output wavelength, optical power, threshold current, efficiency, and operating life can be influenced by temperature. The LDT-5910B provides controlled thermoelectric heating and cooling for compatible laser diode packages and mounts.

A temperature sensor installed near the laser diode supplies feedback to the controller. The LDT-5910B compares the measured sensor value with the selected setpoint and adjusts the bipolar TEC current to maintain the required operating temperature.

Stable temperature control is useful when characterizing laser diodes, measuring wavelength-dependent behaviour, maintaining optical power stability, or operating a laser within a controlled thermal range.

The achievable temperature depends on the thermoelectric module, device power dissipation, heatsink, ambient conditions, sensor location, insulation, thermal-interface quality, and controller settings.

Optical Detector and Electronic Device Applications

The LDT-5910B can also regulate the temperature of compatible infrared detectors, photodiodes, electronic components, and experimental assemblies. Cooling a detector can reduce thermally generated noise, while controlled heating can support temperature-dependent characterization and environmental simulation.

Electronic devices can be evaluated at selected temperatures to examine drift, sensitivity, output stability, threshold behaviour, and other temperature-dependent characteristics.

The controller should be paired with a properly sized TEC and suitable thermal hardware. The TEC, heatsink, sensor, and controlled device must form a stable thermal system for accurate regulation.

Bipolar 4 A Thermoelectric Output

The LDT-5910B uses a bipolar constant-current output capable of driving a thermoelectric module in either direction. Reversing current through the TEC allows the controller to switch between heating and cooling as required to maintain the setpoint.

Maximum output current is 4 A. The documented compliance capability is 4 V at 4 A, and typical maximum output power is 16 W into the specified load.

Output ratings are based on operation into a 1 O load. Actual available heating and cooling performance depends on the connected thermoelectric module and complete thermal assembly.

Adjustable TEC Current Limit

The current-limit control defines the maximum drive current available to the connected thermoelectric cooler. This function helps prevent excessive current from being applied to a TEC with a lower continuous-current rating.

The controller’s current-limit range extends from 0 A to 10.0 A to support operation with an external booster, while the internal LDT-5910B output is rated for a maximum of 4 A. Current-limit accuracy is specified at ±50 mA.

When the instrument is used without a booster, the current limit should not be interpreted as increasing the internal output beyond 4 A. The selected current limit should remain within the ratings of the TEC, wiring, connector, laser diode mount, and thermal system.

The current limit should be configured before the output is enabled. If the TEC rating is unknown, the applicable device or mount documentation should be reviewed before operation.

Temperature Limit Protection

The LDT-5910B supports configurable upper and lower temperature limits. These boundaries help protect the controlled device from operation outside its intended temperature range.

Temperature limits should be selected according to the laser diode, detector, TEC, temperature sensor, mount, thermal adhesive, optical components, and surrounding hardware.

The limit settings do not replace correct thermal design. A suitable heatsink, secure sensor installation, correct TEC polarity, adequate wiring, and stable mounting remain necessary for safe operation.

Thermistor Sensor Compatibility

The controller supports compatible two-wire thermistors over a typical usable range from 25 O to 450 kO. Thermistor sensing current can be selected as either 10 µA or 100 µA.

The 100 µA setting is suitable for compatible lower-resistance thermistors, while the 10 µA setting extends measurement capability to higher resistance values and can reduce thermistor self-heating.

The sensor setting should be selected before temperature control begins. An incorrect sensor type or sensing current can produce an inaccurate displayed temperature and inappropriate TEC output.

A typical 10 kO thermistor is commonly used with laser diode mounts, but the LDT-5910B can be configured for other compatible thermistors using user-defined calibration constants.

Steinhart-Hart Thermistor Calibration

The LDT-5910B converts thermistor resistance to temperature using three user-defined constants based on the Steinhart-Hart equation. The constants are stored in internal nonvolatile memory.

This method allows the controller to be configured for thermistors with different resistance-versus-temperature characteristics. Accurate constants should be obtained from the sensor manufacturer, a calibration certificate, or a suitable thermistor calibration process.

Incorrect Steinhart-Hart coefficients can cause temperature errors even when the controller accurately measures resistance. The constants should therefore be verified before the TEC output is enabled.

AD590 Temperature Sensor Support

The LDT-5910B supports compatible AD590-series current-output temperature sensors. The documented AD590 reverse bias is +8 V DC.

A typical AD590 output is approximately 298.2 µA at 25 °C, with a nominal temperature coefficient of 1 µA/K. The controller uses a two-point calibration method for this sensor type.

The documented AD590 setting accuracy is ±0.2 °C. Actual accuracy depends on the sensor, calibration, wiring, mounting, thermal contact, and user-defined controller configuration.

LM335 Temperature Sensor Support

The controller also supports compatible LM335-series voltage-output temperature sensors. The documented LM335 bias current is 1 mA.

A typical LM335 output is approximately 2.98 V at 25 °C, with a nominal temperature coefficient of 10 mV/K. A two-point calibration method is used for the LM335 configuration.

The documented LM335 setting accuracy is ±0.2 °C. Sensor mounting and calibration should be appropriate for the controlled device and required operating range.

Temperature Range and Setpoint Control

The documented controller temperature range extends from -99 °C to +150 °C. This represents the configurable range of the instrument rather than a guarantee that every thermal system can reach these temperatures.

With a typical 10 kO thermistor, the documented operating range is -20 °C to +50 °C. The actual achievable range depends principally on the sensor, thermoelectric module, load, heatsink, ambient temperature, insulation, and thermal design.

The temperature setpoint is displayed with 0.1 °C resolution. Actual temperature measurement is available with 0.01 °C resolution.

Temperature Accuracy

Using a typical 10 kO thermistor and the documented 100 µA sensing-current configuration, temperature accuracy is specified at ±0.2 °C at -20 °C, 0 °C, 20 °C, and 50 °C.

Temperature setpoint resolution is 0.1 °C at -20 °C, 0 °C, and 20 °C. At 50 °C, the documented resolution is 0.2 °C.

Accuracy values are relative to the calibration standard and depend on the user-defined configuration. Complete system accuracy also includes sensor tolerance, sensor calibration, wiring, mounting, thermal gradients, and the location of the sensor relative to the controlled device.

Short-Term and Long-Term Stability

Short-term temperature stability is specified at 0.005 °C or better under the documented conditions. Long-term stability is specified at 0.01 °C or better.

Temperature stability is strongly affected by the surrounding thermal environment. Room air currents can produce fluctuations of approximately 0.1 °C in an exposed mounting configuration.

For high-stability operation, the laser diode mount or controlled assembly should be protected from drafts, direct sunlight, nearby heaters, cooling fans, mechanical movement, and rapid ambient temperature changes.

Sensor placement and thermal contact are also important. A poorly installed sensor may not accurately represent the temperature of the laser diode or detector being controlled.

Low-Noise TEC Operation

TEC current ripple and noise are specified below 500 µA under the documented broadband measurement conditions. The value is measured from 10 Hz to 10 MHz at 1 A of output current.

Low TEC noise helps reduce small thermal disturbances that could influence laser wavelength, detector response, output power, or sensitive electronic measurements.

System noise can also be affected by cable routing, grounding, shielding, the TEC device, the temperature sensor, nearby electrical equipment, and the controlled mount.

Isolated Output and Grounding

The LDT-5910B output is isolated from chassis ground, allowing either output terminal to be grounded according to the application. The sensor-negative and TE-module-negative connections are internally connected.

Grounding should be planned carefully when the controller is connected to a laser diode controller, photodetector, oscilloscope, data-acquisition system, or other grounded laboratory equipment.

Unintended ground loops can create measurement noise or unwanted current paths. The complete equipment configuration should be reviewed before making external ground connections.

Front-Panel Display and Local Operation

The LDT-5910B uses a four-digit green LED display that can show temperature, TEC current, thermistor resistance, sensor values, setpoints, limits, and configuration parameters.

Maximum displayed TEC current is 4.0 A with the internal output and 10.0 A when a compatible current booster is used. TEC current resolution is 1 mA.

Maximum displayed temperature is 200.0 °C. The temperature setpoint has 0.1 °C resolution, while the measured temperature display provides 0.01 °C resolution.

This unit does not include the optional GPIB interface. All normal operating functions are configured through the front-panel controls.

Automatic Configuration Recall

During power-up, the LDT-5910B performs an indicator test, displays its firmware version, identifies the selected temperature sensor configuration, and recalls the instrument settings stored at the previous power-down.

The startup sensor codes identify the selected thermistor current or integrated-circuit sensor:

• Sensor code 01: Thermistor with 100 µA sensing current.
• Sensor code 02: Thermistor with 10 µA sensing current.
• Sensor code 03: LM335-type temperature sensor.
• Sensor code 04: AD590-type temperature sensor.

Default settings remain available in memory bin 0. Recalling this bin restores the documented factory-default configuration.

Save and Recall Parameter Configurations

The controller stores selected operating parameters in nonvolatile memory. This allows commonly used temperature-control configurations to be recalled without manually re-entering every setting.

Stored parameters can support repeated testing of the same device type or mount. Recalled settings should always be reviewed before enabling the output because temperature limits, current limits, sensor coefficients, and setpoints appropriate for one device may be unsafe for another.

Closed-Case Calibration

The LDT-5910B supports closed-case calibration, allowing calibration adjustments to be performed without opening the instrument enclosure.

Thermistors are calibrated by storing three Steinhart-Hart constants in nonvolatile memory. AD590 and LM335 sensors use a two-point calibration method.

Closed-case calibration simplifies routine maintenance and reduces the need to access internal circuits. Suitable resistance standards, voltage standards, current standards, simulated sensors, calibrated measurement equipment, and thermal references are required for formal calibration.

External Booster Support

Compatible booster modules can be added when an application requires more temperature-control output than the internal 4 A, 16 W capability provides.

The controller can display as much as 10.0 A when an appropriate booster is installed. A dedicated rear-panel signal identifies the presence of a booster in a compatible system.

A booster should not be assumed to be included with the LDT-5910B. Compatibility, output capability, cabling, cooling, load requirements, and associated safety limits should be confirmed separately.

No GPIB Interface Configuration

The ILX Lightwave Model 1233 GPIB/IEEE-488.2 interface was an optional addition to the LDT-5910B. The supplied product configuration does not include this option.

Without the Model 1233 interface, the LDT-5910B does not provide GPIB remote programming or automated IEEE-488.2 control. Temperature settings, sensor selection, current limits, temperature limits, calibration functions, and output operation are controlled locally.

The absence of GPIB does not affect the core temperature-control output, sensor compatibility, closed-case calibration, or front-panel operation.

Typical Applications

• Laser diode temperature stabilization
• Laser wavelength and frequency stabilization
• Laser diode characterization
• Infrared detector cooling
• Photodiode temperature control
• Electronic device thermal characterization
• Temperature-dependent optical testing
• Laboratory photonics experiments
• Laser diode mount control
• Optical component production testing
• Research and development
• Manual benchtop temperature-control applications

Product Overview

Brand	ILX Lightwave
Model	LDT-5910B
Product Category	Precision Thermoelectric Temperature Controller
Output Type	Bipolar constant-current TEC output
Maximum Internal Current	4 A
Maximum Internal Power	16 W typical
Supported Sensors	Two-wire thermistor, AD590, and LM335
Control Interface	Local front-panel control
GPIB Interface	Not installed
Primary Application	Precision temperature control of laser diodes, detectors, and temperature-sensitive devices

 

TEC Output Specifications

Specification	Details
Output Type	Bipolar constant-current source
Compliance Voltage	4 V at 4 A
Maximum Internal Output Current	4 A
Maximum Output Power	16 W typical
Output Rating Condition	Specified into a 1 O load
Current-Limit Control Range	0 A to 10.0 A for internal and compatible boosted configurations
Current-Limit Accuracy	±50 mA
Ripple and Noise	Less than 500 µA under the documented conditions

 

Temperature Control Specifications

Specification	Details
Controller Temperature Range	-99 °C to +150 °C
Typical 10 kO Thermistor Range	-20 °C to +50 °C
Short-Term Stability	0.005 °C or better
Long-Term Stability	0.01 °C or better
Supported Sensor Types	Two-wire thermistor, LM335 voltage-output sensor, and AD590 current-output sensor
LM335 Setting Accuracy	±0.2 °C
AD590 Setting Accuracy	±0.2 °C

 

Thermistor Temperature Accuracy

Temperature	Resolution	Accuracy
-20 °C	0.1 °C	±0.2 °C
0 °C	0.1 °C	±0.2 °C
20 °C	0.1 °C	±0.2 °C
50 °C	0.2 °C	±0.2 °C

 

Temperature Sensor Specifications

Specification	Details
Usable Thermistor Range	Approximately 25 O to 450 kO
Thermistor Sensing Current	10 µA or 100 µA, user selectable
Thermistor Calibration	Three user-defined Steinhart-Hart constants stored in nonvolatile memory
LM335 Typical Output at 25 °C	2.98 V
LM335 Temperature Coefficient	10 mV/K
LM335 Bias	1 mA
AD590 Typical Output at 25 °C	298.2 µA
AD590 Temperature Coefficient	1 µA/K
AD590 Reverse Bias	+8 V DC
LM335 and AD590 Calibration	Two-point calibration

 

Display Specifications

Specification	Details
Display Type	Four-digit green LED
Maximum Current Reading	4.0 A with the internal output or 10.0 A with a compatible booster
Maximum Temperature Reading	200.0 °C
Current Resolution	1.0 mA
Temperature Setpoint Resolution	0.1 °C
Temperature Measurement Resolution	0.01 °C

 

Rear-Panel TEC Connection

Connection	15-Pin D-Sub Assignment
TE Module Positive	Pins 1 and 2
TE Module Negative	Pins 3 and 4
TE Module Shield	Pin 5
Sensor Shield	Pin 6
Sensor Positive	Pin 7
Sensor Negative	Pin 8
Analog Ground	Pin 9
Control Signal	Pin 10
Voltage Limit	Pin 11
Current Limit	Pin 12
Temperature Limit	Pin 13
Booster Present	Pin 14
Digital Ground	Pin 15

 

General Specifications

Specification	Details
Warm-Up Time	One hour for rated accuracy
Operating Temperature	0 °C to 50 °C
Storage Temperature	-40 °C to 70 °C
AC Input Configurations	90 V to 105 V, 105 V to 125 V, or 210 V to 250 V AC, jumper selectable
Line Frequency	50 Hz to 60 Hz
Dimensions	88 mm high x 212 mm wide x 269 mm deep
GPIB Interface	Not installed on this unit

 

Compatible Accessories

Accessory	Model	Application
Single-Instrument Rack Kit	124	Half-width rack mount and filler panel installation
Dual Rack-Mount Kit	122	Rack flanges and enclosure interlocking hardware
Laser Diode Mount	4412	Compatible laser diode mounting and temperature-control platform
Unterminated Interconnect Cable	501	Connection between the temperature controller and a custom TEC or sensor assembly
Calibrated 10 kO Thermistor	510	Calibrated temperature sensing
Uncalibrated 10 kO Thermistor	520	General compatible thermistor sensing
AD590LH Sensor	530	Uncalibrated current-output temperature sensor
LM335 Sensor	540	Uncalibrated voltage-output temperature sensor

 

Connection and Operating Considerations

The thermoelectric module polarity, temperature sensor type, sensor polarity, sensor coefficients, maximum TEC current, voltage requirements, and safe device temperature range must be verified before the output is enabled.

The output should be turned off before a laser diode mount, detector assembly, temperature sensor, or thermoelectric module is connected or disconnected. The current limit should be set to a safe value before enabling output.

Many thermoelectric coolers used in commercial laser diode packages should not be operated continuously above 1 A. The actual TEC manufacturer specification should always determine the permitted current.

Connections can be made through the rear-panel binding posts or the 15-pin D-sub connector. Properly sized conductors should be used for the TEC current, and sensor wiring should be protected from electrical noise and heat-producing conductors.

The heatsink must be capable of dissipating heat from the controlled device, TEC, and electrical losses. Inadequate heatsinking can prevent the system from reaching the setpoint and may increase the risk of thermal damage.

Comprehensive Functional and Performance Testing

The ILX Lightwave LDT-5910B receives comprehensive functional and performance testing before shipment. Testing may include startup, LED display operation, front-panel controls, sensor selection, parameter storage, setup recall, TEC output control, current limiting, temperature limits, and output enable or disable functions.

TEC testing may include bipolar current output, operation into a controlled load, current display, thermal response, heating and cooling direction, compliance behaviour, and current-limit operation.

Sensor testing may include the 10 µA and 100 µA thermistor ranges, resistance-to-temperature conversion, AD590 mode, LM335 mode, sensor display, and calibration-parameter access.

This configuration may also be checked to verify that the optional Model 1233 GPIB interface is not installed. The rear panel, binding posts, D-sub connector, power inlet, voltage configuration, enclosure, ventilation openings, and identification labels may be inspected.

The exact testing scope depends on the available TEC loads, laser diode mounts, thermistors, sensor simulators, temperature references, current standards, interconnect cables, and calibration equipment.

Calibration Before Shipment

When technically applicable and selected, the ILX Lightwave LDT-5910B can be calibrated before shipment. Calibration may include TEC current output, current display, current-limit accuracy, temperature measurement, thermistor resistance measurement, temperature setpoint, AD590 response, LM335 response, and closed-case calibration functions.

Thermistor calibration requires suitable precision resistance standards or a calibrated thermistor simulation system. AD590 and LM335 calibration requires appropriate current or voltage standards and a documented two-point procedure.

A complete temperature-control verification may also use a compatible laser diode mount, thermoelectric module, calibrated temperature sensor, thermal load, and environmental monitoring equipment.

Buyers requiring formal calibration should specify the sensor type, thermistor resistance range, sensing current, temperature points, TEC current points,