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Old 21st July 2013, 06:15 PM   #3581
Dimonis is offline Dimonis  Russian Federation
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moye delo predlozhit
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Old 22nd July 2013, 09:47 AM   #3582
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Anyone tried IRFB4127 mosfets? How much output current can you get with a pair of it? (Assuming that the class-d amp is stable)
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Old 22nd July 2013, 01:20 PM   #3583
paskal9 is offline paskal9  Malaysia
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Quote:
Originally Posted by jlester87 View Post
Anyone tried IRFB4127 mosfets? How much output current can you get with a pair of it? (Assuming that the class-d amp is stable)
it's similar to irfb4227 with higher max current (76A vs 65A on the 4227). in real world application it would most definitely not able to sustain max output current continuously, and most definitely not at high temperature.

if i remember correctly max output current drop to 60% at high temperature. do refer to the temp graph inside the datasheet.
but if you run them slow enough, with wide enough dead time, they'll be relatively cool to the touch even during operation with couple of hundred watt of output.

mine (irfb5615) doesn't even heat up with up to ~500W surges in bass duties.
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Old 23rd July 2013, 03:39 AM   #3584
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Thanks, I am targeting to get 22A RMS output into 2 ohms (1KW) for a pair of IRFB4127. Based on datasheet the mosfet can handle 30A at 150deg c case temp.

I can't measure the total deadtime of my amp because my scope is not capable. But I've added additional 67us of deadtime through gate resistor.

Currently with my lowly supply I only get 490W RMS at 2 ohms load. Rail voltage dropped to 36VAC at full load. Next time I'll use higher voltage.

Here's the vid of the measurements.

Measuring voltage drop of EI Core transformer at full load of JLAmp1000D - YouTube
Measuring JLAmp1000D output at 2 ohms using +-65VDC, supply sagged to +-51VDC - YouTube
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Old 23rd July 2013, 05:41 AM   #3585
paskal9 is offline paskal9  Malaysia
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Quote:
Originally Posted by jlester87 View Post
Thanks, I am targeting to get 22A RMS output into 2 ohms (1KW) for a pair of IRFB4127. Based on datasheet the mosfet can handle 30A at 150deg c case temp.

I can't measure the total deadtime of my amp because my scope is not capable. But I've added additional 67us of deadtime through gate resistor.

Currently with my lowly supply I only get 490W RMS at 2 ohms load. Rail voltage dropped to 36VAC at full load. Next time I'll use higher voltage.

Here's the vid of the measurements.

Measuring voltage drop of EI Core transformer at full load of JLAmp1000D - YouTube
Measuring JLAmp1000D output at 2 ohms using +-65VDC, supply sagged to +-51VDC - YouTube
2 ohm is pretty low for a speaker. you're running for sub duties?

if yes then you don't really need to run them at high speed, and with super tight dead time. if the driver chip supports deadtime configuration, then you could configure them with that. else the gate resistor value would do fine.

i do think for 2 ohm, high power duties like for a sub, bridging the amp is a good idea. it removes the rail sag and you don't have to run the amp with high voltage. possibly getting away with a much smaller power supply with it.
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Old 23rd July 2013, 05:55 AM   #3586
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Quote:
Originally Posted by paskal9 View Post
2 ohm is pretty low for a speaker. you're running for sub duties?

if yes then you don't really need to run them at high speed, and with super tight dead time. if the driver chip supports deadtime configuration, then you could configure them with that. else the gate resistor value would do fine.

i do think for 2 ohm, high power duties like for a sub, bridging the amp is a good idea. it removes the rail sag and you don't have to run the amp with high voltage. possibly getting away with a much smaller power supply with it.
Yes it's for sub duty, I used IR2110, it doesn't support deadtime configuration. So I just added 67ns of deadtime through gate resistor.

Quote:
Originally Posted by paskal9 View Post
mine (irfb5615) doesn't even heat up with up to ~500W surges in bass duties.
When you bridge your amp, there is less sag based on your experience but will it overload the transformer more and have heat problems? compared to halfbridge configuration?
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Old 24th July 2013, 12:05 AM   #3587
stewin is offline stewin  Kenya
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hi all . here is my amp . i have decided to go the simple way . for more power i will use two channels in bridge mode . your ideas and views are appreciated
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File Type: jpg gtG 1100 schematic.jpg (317.6 KB, 744 views)
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File Type: pdf gtG 1100 schematic.pdf (35.6 KB, 172 views)
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Old 24th July 2013, 02:59 PM   #3588
exflaco is offline exflaco  Armenia
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Stewin coul use, not used tl as inverter to bridge mode ,good design y sugest a OCP and Speaker protect for you amp the same IRS1500
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Old 24th July 2013, 05:51 PM   #3589
stewin is offline stewin  Kenya
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Quote:
Originally Posted by exflaco View Post
Stewin coul use, not used tl as inverter to bridge mode ,good design y sugest a OCP and Speaker protect for you amp the same IRS1500
i decided to pass over protection so as to make a separate board with relay and ocp . tl ic is used as preamp for the amp
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Old 24th July 2013, 10:42 PM   #3590
exflaco is offline exflaco  Armenia
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ok but colud use 4 stage from ic to make inverter usable in only in bridge mode (ic1b)no need extra inverter wen use bridge mode,you now a mind?in the same pcb friend
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