FAQ1113

Answer

Both laser drivers are viable options for driving 4 A to your laser diode, and there are a number of points to consider before deciding which driver is best for your application.

Both drivers accept external modulation inputs, both have laser safety features to protect your investment, and both can be operated in either Constant Current or Constant Power mode.

Compared to the MPL drivers, the PLD drivers are physically smaller. The PLD series drivers are electrically more efficient, and are driven with a 5 V power supply. For added versatility the laser and PLD driver can be driven with separate power supplies, thereby accommodating compliance voltage values as high as ~28 V. The modulation bandwidth of the PLD drivers is higher than the MPL drivers, and so the output current noise is also somewhat higher. Another key difference: if the driver reaches the user-defined limit current the PLD safely switches off the laser by shorting the laser diode anode and cathode.

The MPL drivers have a lower modulation bandwidth, and also lower noise level on the output current. They require a power supply voltage of 12 – 15 V, and are not as electrically efficient as the PLD drivers because the limit circuit continuously draws current, even if the laser drive current is off. The continuous-draw of the limit circuit increases power consumption and requires the MPL be adequately heat-sinked even in cases where the laser output is on only intermittently. If the driver reaches the user-defined current limit setting, the output current is clamped at the limit setting but the laser is not switched off.

To find out more about the differences between the two product families, here are links to the datasheets:
MPL Series Datasheet
PLD Series Datasheet

In both cases a suitable heatsink is required – be sure to check that you are operating within the capabilities of the driver using the Safe Operating Area calculator: Safe Operating Area Calculator for Laser Drivers