Dual drivers, and new revision quad drivers in stock

[-bart-]

First of all make sure all your diodes are isolated from each other.
Or they should at least have a common gnd. Otherwise things will surely go bad.

[nuphotonix]

Wth the quad driver its a no brainer I thought. I only have to worry about the current values and the amout of heat the FET have to eat

[Badpip]

Yes, you can adjust with the diodes connected. Just make sure to turn the trimmers fully down first (CCW).

You can measure the current by checking the voltage between the A pad and testpad on each channel. 0.1V = 1A, 0.2V = 2A etc.

/Thomas

[andy_con]

any update on a single driver?

[nuphotonix]

OK... my 650nm laser is a c-mount type and has a postage size peilter cooler under it. this is the only laser that has a TEC in it. Can I use the Quad driver to run the TEC? If so.. how?

[Badpip]

OK... my 650nm laser is a c-mount type and has a postage size peilter cooler under it. this is the only laser that has a TEC in it. Can I use the Quad driver to run the TEC? If so.. how?

It's possible, but you need to know the current rating of the peltier.

I have seen people use the drivers for open loop temperature control, but it's not something I would recommend - first of all, you can't connect the thermistor anywhere, so temperature stability will be low. This is not critical for a direct diode module though.
You have to let the modulation signal for the diode control the peltier as well - this means that it will turn on and off with the diode - pulsed operation.

Peltier manufacturers generally advice against pulses, as they can shorten the lifespan - I have seen papers disproving this claim though, so it's kind of a grey zone.

Cheers,
Thomas

[absolom7691]

It's possible, but you need to know the current rating of the peltier.

I have seen people use the drivers for open loop temperature control, but it's not something I would recommend - first of all, you can't connect the thermistor anywhere, so temperature stability will be low. This is not critical for a direct diode module though.
You have to let the modulation signal for the diode control the peltier as well - this means that it will turn on and off with the diode - pulsed operation.

Peltier manufacturers generally advice against pulses, as they can shorten the lifespan - I have seen papers disproving this claim though, so it's kind of a grey zone.

Cheers,
Thomas

He could turn the bias up so that when the laser is off, there is still current going to to the TEC. That's what I intend to do on my setup. When the modulation is at 0v, the TEC will still be running at about .25A. This will keep it cool so when the laser turns on, the initial cooling time for the TEC is minimized. I wonder if that will help the pulses shortening the life of the TEC.

[Badpip]

He could turn the bias up so that when the laser is off, there is still current going to to the TEC. That's what I intend to do on my setup. When the modulation is at 0v, the TEC will still be running at about .25A. This will keep it cool so when the laser turns on, the initial cooling time for the TEC is minimized. I wonder if that will help the pulses shortening the life of the TEC.

Yes, that should give a lot less thermal stress.

But again - the pulses might not be a big deal - I have seen people wire the peltier in series with the LD

A voltage divider with a thermistor and a resistor on the input might work too.

/Thomas

[absolom7691]

I have seen people wire the peltier in series with the LD

Interesting and scary way to current limit the diode!

[megaton]

Hi Thomas

Drivers are here.

Thanks and cheers,
Ed