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since the laser diodes only pull the current voltage they need would it be ok to drive an ir diode with any available driver(lava,rkcstr,ddl)?
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ir laser driver...
- Thread starter ndrew2505
- Start date
I have used IR diodes with DDL and rckstr drives fine. However I remember reading on here that the lavadrive won't work for IR diodes....
Found it
No, it wouldn't work.. An IR diode has a forward voltage of <2V.. The FlexDrive can't regulate the current if the output voltage is under 2.7V. That's because the current sensing IC on it is powered by the driver output and needs at least 2.7V to work. If the driver output is under 2.7V, the current sensing IC stops working, and the driver dumps a shit load of current through the load.
So in order to drive loads with a Vf of under 2V, you need to add a Si diode or two, to increase the combined Vf above 2V. This of course decreases the efficiency of the setup, due to power lost on the Si diode. But for testing that doesn't really matter..
You can just solder some Si diodes in series (just make sure their combined Vf is between 2.7-6V). I use a CREE LED and three diodes in series with it, to test my driver. But the three diodes in series were a bit too much for the FlexDrive, as it came close to, or above 6V and started blinking, especially since it was powered by my switching PSU at that time (the FlexDrive doesn't like my PSU). CREE and two Si diodes were a good approximation of a PHR tho.
Of course, when the driver works as it is supposed to, the actual Vf of the dummy doesn't have to be anywhere near the actual load's Vf, it just has to be in range.[/quote]
Should help
Found it
IgorT said:
No, it wouldn't work.. An IR diode has a forward voltage of <2V.. The FlexDrive can't regulate the current if the output voltage is under 2.7V. That's because the current sensing IC on it is powered by the driver output and needs at least 2.7V to work. If the driver output is under 2.7V, the current sensing IC stops working, and the driver dumps a shit load of current through the load.
So in order to drive loads with a Vf of under 2V, you need to add a Si diode or two, to increase the combined Vf above 2V. This of course decreases the efficiency of the setup, due to power lost on the Si diode. But for testing that doesn't really matter..
You can just solder some Si diodes in series (just make sure their combined Vf is between 2.7-6V). I use a CREE LED and three diodes in series with it, to test my driver. But the three diodes in series were a bit too much for the FlexDrive, as it came close to, or above 6V and started blinking, especially since it was powered by my switching PSU at that time (the FlexDrive doesn't like my PSU). CREE and two Si diodes were a good approximation of a PHR tho.
Of course, when the driver works as it is supposed to, the actual Vf of the dummy doesn't have to be anywhere near the actual load's Vf, it just has to be in range.[/quote]
Should help
