Old 05-15-2012, 06:52 PM #1
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Default Voltage spike when switching on (micro flex V5 driver)

Hi All,

I notice that when I turn on my driver by hitting a switch attached to my battery I get a transient voltage spike... this is bad for my application because I want the light output to be well controlled and a super bright spike at the beginning is very undesirable. Anyone have any suggestions on eliminating this? I was thinking maybe an inductor between the two leads of the diode so that the transient spike would be shorted... but there are problems with doing that.. like the discharge.

Anyway, if anyone has a simple solution I'd appreciate it.


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Old 05-15-2012, 07:14 PM #2
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Default Re: Voltage spike when switching on (micro flex V5 driver)

No, an inductor would make things much worse!

Do NOT do that.

However, try adding more filter capacitance on the output of the driver. That may solve your issue.
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Old 05-16-2012, 06:28 PM #3
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Default Re: Voltage spike when switching on (micro flex V5 driver)

How did you measure the spike?

If you're using an inductor, you want it in series. Using it in parallel would give you no output and potentially ruin the driver.
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Old 05-17-2012, 02:59 AM #4
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Default Re: Voltage spike when switching on (micro flex V5 driver)

Yeah, inductor in series - what I wrote was wrong.

Measured the spike using an oscilliscope - spike is clearly there based on LD output too though. If I just hold it in front of a power meter and flip it on I get Overload message then a second later a reading (overload isn't because it's actually brighter than the power meter can handle but just because it auto-ranges and it doesn't adjust before it reduces power). I might just move to a lower power blue LD to reduce risk.
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Old 05-17-2012, 03:50 AM #5
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Default Re: Voltage spike when switching on (micro flex V5 driver)

Duration and magnitude? Could you get a screen shot? Was a load attached when you took your reading?
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Old 05-17-2012, 04:02 AM #6
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Default Re: Voltage spike when switching on (micro flex V5 driver)

Yeah I had six diodes(.7v drop/each) + 1 ohm resistor (5W because i had one laying around) -- I'll see at the lab tomorrow if I can get a screenshot, shouldn't be a problem but that driver is soldered directly to diode now, I'll see if it's reproducible on the other drivers (if not i should just toss the driver I suppose)
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