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apchar
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Join Date: Jun 2010
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Need to Pump 2 A Through an LED for 40nsec

06/21/2010 11:32 PM

I want to pump a 2 amp 40 nsec pulse through an IR LED (Vishay TSHF5210) every 10msec or so. I have to keep the driver cheap & simple because I'm cheap & simple. I hope I can find something in an SOIC package since I can't see anything smaller.

I was going to use a MOSFET driven with a MOSFET driver but I notice that MOSFET drivers contain MOSFETS so why bother with the MOSFET that would be driven by the MOSFET driver if I can drive the LED directly with the MOSFET driver.

There are a few MOSFET driver chips that can handle the current and speed that are relatively cheap (< $2). I know it's not the usual application but is there any reason a MOSFET driver can't drive an LED?

Thanks
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CraziestOzzy
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#1

Re: need to pump 2 A through an LED for 40nsec

06/22/2010 12:10 AM

I would say, without looking into your situation further and reading up on your desired LED type and not knowing the type of MOSFET driver you wish to use...at 10msec between pulses at 40nsec a pulse, you may have problems with heat build up. It would not hurt to see if your desired SOIC driver package can reliably handle your situation without the MOSFET. BUT, I use the MOSFET drivers for reliable off and on switching of MOSFETS under a load and the drivers have numerous protections available to you that link to an outside MOSFET for reliable and safe operation.

If you use just the output of a MOSFET driver with none of the other important functions contained within a MOSFET driver's output/inputs, I doubt your desired switching operation will be reliable in the long term. Best to use a MOSFET driver with an external MOSFET and use the protection features inherrent in a MOSFET driver.

Then again, you may try linking the MOSFET drivers own protection output/input sensors/controls to its own internal MOSFET that you use to drive the LED...but that capability depends on your internal MOSFET's circuit flow chart.

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apchar
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#2

Re: need to pump 2 A through an LED for 40nsec

06/22/2010 7:32 PM

Is heat really going to be a problem when the duty cycle is only .0004 % ? That's about 16 microwatts average power.
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CraziestOzzy
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#3
In reply to #2

Re: need to pump 2 A through an LED for 40nsec

06/22/2010 10:06 PM

I was careful with my English, "may" is very much the word to look at in my answer. Point to consider IS the dissipation of heat between each cycle.

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apchar
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#4

Re: Need to Pump 2 A Through an LED for 40nsec

06/25/2010 3:49 PM

Crazy. There was nothing in your last reply.
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CraziestOzzy
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#5
In reply to #4

Re: Need to Pump 2 A Through an LED for 40nsec

06/25/2010 8:25 PM

refresh your "browser"...or if you were not being an arse in your last comment, top right of my reply there is a "+" sign, click it to view off-topic comments that are hidden by default

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Previous in Forum: what are the "odds" of using odd no. of units?   Next in Forum: Switching the Polarity of the DC Power Source
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