21. LPLDD-5A-24V-PID

Product Description

This is the 4th version of the professional driver for laser diodes with a built-in digital temperature controller using the PID algorithm. Its size allows for mounting it in small devices such as compact laser projectors. The driver is available in two versions. One includes the heatsink, the second one is without it and is dedicated to users who would like to use their own heatsink or optic plate.

The logic part of the driver is powered from TEC line, it allows to use 3.3 V PSU to power the infrared diodes without the big amount of dissipated heat. TEC part should be connected even if not used to the voltage in 7.5 V - 24 V range.

Despite its small size, the driver is able to work with thermocouples (Peltier modules) such as 12706, 12708, 07113, and many others that draw up to 15 A of current. Despite the high current, thanks to using PWM the controller does not heat up. Used PID algorithm learns the behavior of the system, hence quicker reacts to changes in temperature and provides higher accuracy of stabilization. The driver easily handles all laser diodes of up to 5 W, and at the customer's request, it is possible to customize the driver up to 10 A version. Separate laser diode supply voltage input and TEC input enable the selection of any components the driver can work with. Analog input allows for the modulation of the current flowing through the diode up to 100 kHz. Two potentiometers are used to set the values of maximum diode current and bias current. The third potentiometer is responsible for setting the setpoint temperature in the range of 0 to 40 degrees Celsius. The possibility to power laser diodes of any wavelength and control the Peltier modules with a rated voltage from 7.5 to 24 V and current up to 15 A make this driver truly unique and extremely versatile. Diode line can be powered with voltages from 3 V up to 24 V so it makes it fully functional for any kind of laser diode.

Main features

Screw connectors - smaller size easy to connect the wires

Test jumper - the possibility of switching on the driver without external analog signal

Current monitor output - the convenient place to measure the current flowing through the diode

Signal diodes: diode enable, TEC, warning

Labels on the board - more intuitive and easier to set

High TEC current - up to 15 A

Added labels on the board - more intuitive and easier to set

Technical Data

TEC maximum current15 A
TEC supply voltage7.5 - 24 V
Maximum diode current5 A
Current set by default~2000 mA
Laser diode supply voltage3.3 - 24 V
Modulation voltage (analog)0 - 5 V
Maximum modulation frequency100 kHz
Current monitor100 mV / 1 A
Soft startYES - 2000 ms
Temperature sensor10k NTC thermistor
Temperature stabilization accuracy+-0,1*C
TEC indicatorYES - blue LED diode
Laser diode indicatorYES - red LED diode
Over temperature protectionYES >50*C
Board dimensions58 mm x 45 mm
Mounting holes distance38 mm x 48 mm
Transistor typeN-MOSFET
Maximum heat dissipated40 W

How to connect the LPLDD 5A PID

Connecting "Test jumper" allows to switch on the driver without external analog signal.

While Offset jumper is not connected the Offset trimmer is not working.

Temperature trimmer allows setting the working point of TEC in the range of 0-40 degrees Celcius.

How to power supply the LPLDD 5A PID

Thanks to the dual power line of the driver it is possible to the power supply the driver in a various way. In order to power, the logic part of a driver TEC line must be always connected to proper voltage 7.5 - 24 V. Laser diode part cannot work alone.

  • Laser diode driver with TEC and two PSU.

If the driver is working with TEC, the double power supply can be used. The one for laser diode should be 3.3-24 V, meanwhile the second for TEC should be 7.5-24 V. Analog modulation should be 0-5 V.

  • Laser diode driver with TEC and one PSU.

If 7.5-24 V PSU is used, it can power supply both, laser diode as well as TEC. Analog modulation should be 0-5 V.

Connecting TEC to the driver

If one connects the TEC accordingly to the picture below, the side with the label will be cold during the driver’s work. If one connects the cables in the reverse order, the side without the label will be cold.

Checking the current set on the driver

The driver is fitted with a current monitor. Safe test of the current can be made without using a laser diode. Instead of using the laser diode, use a test load resistor (0.5-1 Ω 5 W) with a silicon diode then check/set the current using the current monitor. Regulate the current with "Current trimmer". Each 100 mV measured by voltmeter/oscilloscope means 1 A will be flowing through the laser diode.

It is also possible to check/set the current with the use of a laser diode. In such a situation, the measurement is the same as before.

We recommend to check/set the current using the test load resistor because it is much safer and will not harm the laser diode.

Recommendations and requirements

The minimum diode input voltage should be higher or equal to 3.3 V, in other situations it is given by the formula:

Vin = 0,4* I + Vd + 0,6 V

Vin - input voltage
Vd - diode working voltage
I - desired maximum current

Modulation input can be used as TTL input with its logic levels of 0 V and 5 V or as an analog input. Analog modulation means that by using 2.5 V on ANG input you get 50% of the current flowing through the laser diode, analogically by using 4 V you get 80% of the current, etc.

You should be very careful not to cause a short circuit between the + (VCC) of the power supply and - (GND) of the analog input, as a thin GND analog path can be irreparably damaged.

The MOSFET/MOSFETs must be isolated from the heatsink/plate with silicon pad as well as the plastic sleeve. A short circuit between MOSFET and heatsink/plate can damage the driver and can be dangerous for the Laser Diode.

We recommend the use of power cables with the cross-section of at least 0.5 mm2.


The circuit responsible for powering a laser diode is protected against reversed polarity. The high current Schottky diode of an extremely low forward voltage secures the laser diode against connecting reversed voltage with the aim of protecting frequently the most expensive part of the entire device - a laser diode. In turn, the low forward voltage does not cause excessive heat loss during normal operation.

The analog input is protected by a 5V1 Zener diode on occasion there appears the voltage higher than 5V. Despite everything, this input should not be used with higher voltages.

A microcontroller ensures the proper operation of the entire system.

At the start, the microcontroller is checking the connection with a thermistor. If there is no thermistor used the WARNING LED is blinking but the driver is still working. If the connection with the thermistor is lost during normal work, the microcontroller turns off the laser diode supply circuit and does not allow for its further load, it also switches off the DIODE LED and switch on WARNING LED. The TEC line is also switched off. The same situation happens when the thermistor reaches the temperature above 50 degrees Celsius

The driver is fitted with a two-second soft-start designed to protect the laser diode against switch-on effects.

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