FlexMod P3 problems

[calsticker]

Hey all

I'm using a Flexmod p3 driver to provide current to my laser diode but I cannot get it to even provide any output.


There was only one instance where I was able to set the 0Bias and Gain where it worked perfectly and could be driven by a PWM signal afterward. However, the next day it just stopped working again.

I followed the instructions provided in the manual but the fault LED stays on no matter what I do. I set the interlock to the V+ potential and have the output wired into a multimeter. I'm able to set the 0Bias setting with M+ shorted. When I connect M+ to V+ potential to adjust the gain, after 7 seconds the fault LED turns on, or sometimes after 7 seconds the DMM would read 'overload.'

Any advice is appreciated.

Thanks

 

[Cyparagon]

What diode, what power source, what are you heat sinking the driver with, and how are you connecting your DMM? Please be specific.

 

[calsticker]

What diode, what power source, what are you heat sinking the driver with, and how are you connecting your DMM? Please be specific.

Since I'm just testing it for now, I'm using an old M140 diode that is burned out (hardly puts out 30mW). Ultimately I want it to power a S60J diode at 450mA max. The power supply I'm using now is just a DC power supply at 5V and the driver has the heat sink that came with it. I figured it should be sufficient for the current ranges I'm using. I have the dmm +/- at the output +/- of the driver.

We're using PWM signals to turn the laser on/off. When we hook it up the the DMM, we can measure the current at the values I wanted. But when I wire the outputs to the diode and send a signal, the diode blinks intensely momentarily and then the fault LED comes on. Could this be because the diode is messed up?

Also, what could cause the DMM to read overload? Is this a rapid variation in current? Sometimes the DMM will blink overload for a second and then go to the current level.

Thank you

 

[Cyparagon]

I found the problem. You're doing pretty much everything wrong

This is a linear driver. That means the Supply voltage needs to be a couple volts higher than the load voltage. Raise your input voltage to 7V or more. This also means you cannot tie M+ to V+.

The included heat sink is inadequate for most loads. You need something bigger.

Using a DMM to measure the current of linear drivers is okay, but only if you're in the proper voltage parameters.

DMM reading OL on what range? If it's the 10A range, your driver has been damaged and needs to be replaced. Under no conditions should the flexmod output >10A.

 

[calsticker]

Thanks for the reply.

The DMM is measuring at the 500mA range. We shouldn't have an output of over 500mA.

I think there is something wrong with the driver. When I set the M+ to GND, there are no issues and it runs at the preset 0Bias setting. However, when I connect it to the modulation source, the fault LED lights up. Or sometimes it will provide current, then the LED will blink after 7sec and then stay lit up after 14sec.

When I first got it, I was able to set the gain and 0Bias with no problem and connect it directly to the DMM to monitor the current output. A couple days later I went ahead and soldered on the wires and that's when these issues began.

Any help is appreciated.
Thanks

I found the problem. You're doing pretty much everything wrong

This is a linear driver. That means the Supply voltage needs to be a couple volts higher than the load voltage. Raise your input voltage to 7V or more. This also means you cannot tie M+ to V+.

The included heat sink is inadequate for most loads. You need something bigger.

Using a DMM to measure the current of linear drivers is okay, but only if you're in the proper voltage parameters.

DMM reading OL on what range? If it's the 10A range, your driver has been damaged and needs to be replaced. Under no conditions should the flexmod output >10A.

 

[Cyparagon]

Thanks for the reply.

Did you READ the reply?

 

[calsticker]

I did. I'm supplying V+ with 9V. I am able to adjust the zero bias to the output that I desire, however, when I add any voltage to the M+ signal, the fault LED blinks after 7 seconds and then after another 7 seconds, it stays on and the driver does not give out any current.

We are measuring the output of the diode using a power meter now instead of an ammeter. We can set the zero bias to give an output of 600mW so I know that the current driver is able to supply a large amount of current.

I appreciate your help, I just don't understand why the fault LED keeps triggering when we supply voltage to the M+ input.

Thank you

Did you READ the reply?

 

[Cyparagon]

What is the DMM current reading when the fault activates? What voltage are you applying to M+?