LPLDD-5A-24V-PID Laser Diode Driver

About the LPLDD-5A-24V-PID-H Laser Diode Driver

The LPLDD-5A-24V-PID is a professional 5 A laser diode controller with a built-in digital temperature controller utilizing the PID algorithm. Designed with a compact form factor, it seamlessly integrates into small devices like compact laser projectors. Despite its small size, the driver is able to work with Peltier modules such as 12706, 12708, 07113, and many others that draw up to 15 A of current.

Laser diode lines of any wavelength can be powered with voltages from 3 V up to 24 V. Analog input allows for the modulation of the current flowing through laser diodes up to 100 kHz. The driver is equipped with a current monitor output, providing a convenient measurement point for monitoring the diode's current flow. Two potentiometers are provided to adjust the maximum diode current and bias current. The third potentiometer is responsible for setting the setpoint temperature in the range of 0 – 40 degrees Celsius.

With the inclusion of a test jumper, the driver can be effortlessly activated without an external analog signal. To enhance usability, the driver incorporates signal diodes (LEDs) for diode enable, TEC, and warning indications.

Recommendations and requirements

• The minimum diode input voltage should be higher or equal to 7 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 - operating current
• Take great care to avoid short circuits between the + (VCC) of the power supply and -(GND) of the logic input or monitor input, as this can irreparably damage the thin logic GND paths.
• The modulation input can be utilized as a TTL input with logic levels of 0 V and 5 V, or as an analog input. Analog modulation allows adjusting output power by using specific voltage levels (e.g., 2.5 V for 50% output power, 4 V for 80% output power, etc.). This input can also be used as PWM input. The only requirement is that the base frequency of the PWM signal is in the range of 5-20 kHz.
• We recommend the use of power cables with a cross-section of at least 0.5 mm2.
• The TEC part should be connected to voltage in the 7.5 V - 24 V range, even if not used. The Peltier module can operate only in cooling mode.
• Depending on the used laser diode and PSU an additional fan might be required to ensure the proper cooling of MOSFETs. Excessive heat may damage the MOSFETs and laser diodes may be burned.

Protection

The laser diode power circuit is safeguarded against reversed polarity using a high current Schottky diode with low forward voltage, protecting the laser diode from incorrect voltage connections while minimizing heat loss.

To safeguard the analog input, a 5V1 Zener diode is incorporated to handle voltages exceeding 5 V. However, it is essential to avoid using higher voltages with this input.

A microcontroller ensures the proper operation of the entire system. It checks the connection with a thermistor at startup. If no thermistor is detected, the WARNING LED blinks, but the driver continues functioning. In the event of a lost thermistor connection during normal operation, the microcontroller shuts off the laser diode supply circuit, prevents further loading, turns off the DIODE LED, and activates the WARNING LED. The TEC line is also disabled. The same actions are taken when the thermistor temperature exceeds 50 degrees Celsius.

The laser controller includes a 2s soft-start feature designed to safeguard laser diodes from harmful switch-on effects.