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antedeluvian
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Re: smart PWM "mosfets"
antedeluvian   11/21/2013 9:42:26 AM
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salbayeng

I've also looked at using the UC2845 (usually a current mode flyback PWM driver) driving any old mosfet. If you average the PWM signal (while it's running closed loop)   as an analog voltage , you can determine whether it is open or short circuit.

This is a great idea. You shoul;d submit it to EDN's Design Ideas- make yourself a few bucks.

 

Have you seen the DRV101

Thnaks for the pointer. I recently saw a TI part, but was only rated to 20V, for automotive applications. This one I can use!

salbayeng
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smart PWM "mosfets"
salbayeng   11/21/2013 7:29:49 AM
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Hi Aubrey , 

More good stuff in your blog as always.

Unfortunate that the only units with status indication, the ZXMS6002G and ZXMS6003G have a feeble 500mohm  Rds , what kind of automative load only uses 1A? , heck a simple PTC placed in close proximity to the MOSFET tab would provide sufficient protection for a 12v / 1A load.

Have you seen the DRV101 , in a TO220 5pin  package , meant for solenoid driver, hits it hard at first then throttles back to PWM, interestingly it has a fault output for both under and overcurrent. 

http://www.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=drv101&fileType=pdf 

I've also looked at using the UC2845 (usually a current mode flyback PWM driver) driving any old mosfet. If you average the PWM signal (while it's running closed loop)   as an analog voltage , you can determine whether it is open or short circuit. But it won't go to 100% duty so only good for bulbs and coils / motors.

Underdriving the gate is a big MOSFET killer , so some kind of de-saturation detector would be helpful.

Brian@BDH
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Re: Another approach to current monitor
Brian@BDH   9/11/2013 3:58:31 PM
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@Aubrey: Re: Do you know if there is a data sheet available? Perhaps it is still preliminary.

Yes, the datasheet is in Max's inbox - I asked him to forward it to you since I didn't have your email address readily available :-) 

Correct, the part does not launch in production until Dec13/Jan14, so the datasheet is still a Target datasheet and the Final datasheet has not been released on the website yet.  However, samples are available!

 

Max The Magnificent
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Re: Very much useful
Max The Magnificent   9/11/2013 1:28:50 PM
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@Sanjib.A: Hi Max, Thanks a lot for sharing the guide.

It's my very great pleasure -- I think it contains a lot of useful information.

Sanjib.A
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Re: Very much useful
Sanjib.A   9/11/2013 1:02:56 PM
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Hi Max, Thanks a lot for sharing the guide. This is a pretty elaborated description about the calibration methodology and the advantages of the newer devices with advanced current sensing technique, which make the calibration easier. I am also impressed to see the option for "no calibration", where the "typical" slope and offset correction factors could be used from the datasheet instead of adding a calibration process during production...this is good for the application where accuracy is not that important. Thanks!

Max The Magnificent
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Re: Very much useful
Max The Magnificent   9/11/2013 10:53:29 AM
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@Sanjib.A: I will check out your & Max'x blogs.

I think Antedeluvian was referring to my comment where I mentioned Infineon's ADVANCED SENSE Calibration and Benefits guide (http://tinyurl.com/ADVANCED-SENSE-1-0)?

I would be very interested to hear your thoughts on this guide -- Max

Max The Magnificent
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Re: Another approach to current monitor
Max The Magnificent   9/11/2013 10:50:47 AM
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@Antedeluvian: Perhaps I should do a blog on current measurment?


Yes please :-)

antedeluvian
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Re: Another approach to current monitor
antedeluvian   9/11/2013 9:16:24 AM
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Brian

Infineon TLI4970 High-Precision Current Sensor

This looks a very interesting device. I only seem to find a product brief. Do you know if there is a data sheet available? Perhaps it is still preliminary. I did find a YouTube video, but not much else. There is also supposed to be an evaluation kit, but I can't find stock of it or the part anywhere.

Brian@BDH
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Re: Another approach to current monitor
Brian@BDH   9/10/2013 11:42:27 PM
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@antedeluvian: Re: Perhaps I should do a blog on current measurement?

You might like these devices when you need/want an integrated solution!

Infineon TLI4970 High-Precision Current Sensor

 

Sanjib.A
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Re: Very much useful
Sanjib.A   9/10/2013 10:48:22 PM
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True, I agree with you on that it better be calibrated along with the ADC as a system. One could use the ADCs often available built-in the modern microcontrollers. I will check out your & Max's blogs. Thanks for the information!

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