Breaking News
Blog

Using MCUs: Intelligent Digital Power Outputs

NO RATINGS
View Comments: Threaded | Newest First | Oldest First
David Ashton
User Rank
Blogger
Natty devices...
David Ashton   9/9/2013 7:40:27 PM
NO RATINGS
Never heard aabout these before, thanks Aubrey.  I can think of a few uses for them apart from the intended automotive ones.

antedeluvian
User Rank
Blogger
Re: Natty devices...
antedeluvian   9/9/2013 8:16:31 PM
NO RATINGS
Hi David

Aside from standard I/O type stuff, we have used the IR part as a form of peak current shutoff on a power supply using the current mirror to drive a comparator.

David Ashton
User Rank
Blogger
Re: Natty devices...
David Ashton   9/10/2013 5:21:37 AM
NO RATINGS
Thanks, Aubrey.  I was thinking of using it on an analogue variable power supply, before the main pass transistor.  Apart from being able to switch the output off electronically, you could get a ground-referenced voltage proportional to output current - very useful for measuring output current using a standard DVM module - which on a variable PSU is otherwise not easy..  Looking at the specs for your IR3314, I think it would work  ok.  I'll look at the others as well.  Are these things expensive?

antedeluvian
User Rank
Blogger
Re: Natty devices...
antedeluvian   9/10/2013 8:48:48 AM
NO RATINGS
David

 Are these things expensive?

This is an incredibly complex question. What is a good price for me is really expensive for someone designing for the mass market. Before I overwax philosophical though, it seems to me you are only interested in a single unit, so I will only state the price from Digikey for the automotive version AUIR3314S is C$4.81. (C$1 is approx US$1.) Apparently it is still available in a TO220 pack, if you want ease of connection although you may struggle to find it in that format although I see Digikey have 6 at C$6.95 at the moment and Mouser have it in abundance.

Max The Magnificent
User Rank
Blogger
Check out the ADVANCED SENSE Guide
Max The Magnificent   9/10/2013 10:47:13 AM
NO RATINGS
Speaking of high-side power switches with protection and diagnostic functions, have you read Infineon's ADVANCED SENSE Calibration and Benefits guide (http://tinyurl.com/ADVANCED-SENSE-1-0)?

As an aside... I happen to know that the guys who wrote this little rascal are incredibly clever and handsome and witty ... the words all appear to have been hand-picked at the crack of dawn while the morning dew is still glistening on them, and it goes without saying that the quality of the diagrams is fantastic...

antedeluvian
User Rank
Blogger
Re: Check out the ADVANCED SENSE Guide
antedeluvian   9/10/2013 10:59:34 AM
NO RATINGS
Max

the words all appear to have been hand-picked at the crack of dawn while the morning dew is still glistening on them,

These are the exact same words that I saw on an old recipe for making Rose Petal Jam. (new recipes like this, lose the magic!) I printed the manual out, shredded it and spread it on bread- but it doesn't taste anything like jam!

Seriously though- a well written document. Infineon obviously has good taste in authors.

Max The Magnificent
User Rank
Blogger
Re: Check out the ADVANCED SENSE Guide
Max The Magnificent   9/10/2013 11:03:10 AM
NO RATINGS
@antedeluvian: These are the exact same words that I saw on an old recipe for making Rose Petal Jam...

I thought you were joking, but I wen tto read the recipe (I couldn;t help myself) and saw the following:

If you're picking the roses yourself, the best time is in the late morning, after the dew has dried and before the strong afternoon sun.

I'll have to remember this recipe :-)

antedeluvian
User Rank
Blogger
Re: Check out the ADVANCED SENSE Guide
antedeluvian   9/10/2013 11:10:00 AM
NO RATINGS
Max

Just going through the document and looking at section 2.5 on characteristics of straight lines. Seemed rather conicidental- have you seen my current blog on calibration over on Planet Analog?

Max The Magnificent
User Rank
Blogger
Re: Check out the ADVANCED SENSE Guide
Max The Magnificent   9/10/2013 11:33:35 AM
NO RATINGS
@antedeluvian: ...have you seen my current blog on calibration over on Planet Analog?

I hadn't -- but I have now :-)

Sanjib.A
User Rank
CEO
Very much useful
Sanjib.A   9/10/2013 2:05:40 PM
NO RATINGS
@Aubrey, thank you for sharing information on these current sense devices. I was not aware of these devices and never used so far. But looks like I sould be able to make use of these devices in my designs. You mentioned about calibration. Do these devices require runtime calibration or one-time calibration in the factory before shipping? Without calibration does it make a huge deviation or could the tolerance be accommodated in the firmware if too much of accuracy not needed?

antedeluvian
User Rank
Blogger
Re: Very much useful
antedeluvian   9/10/2013 2:30:47 PM
NO RATINGS
Sanjib

You mentioned about calibration. Do these devices require runtime calibration or one-time calibration in the factory before shipping?

We would generally calibrate as part of the test process during manufacture. I don't think they need run time calibration- if one needed that sort of accuracy I would imagine that one would use some different form of external current measurement. I would add that I have only worked with the IR device. The others may be different.

Without calibration does it make a huge deviation or could the tolerance be accommodated in the firmware if too much of accuracy not needed?

I am sure you can use software to handle the variations. The current mirror ratio can vary from 4800 to 6000 with a nominal value of 5300- a variation of about +/- 10%. There is a variation of +/-5% over the temperature range and an offset of about 150mA at a 2A output. You make the choice based on your application, I guess.

If you look at the earlier post (in this thread) from Max (about 5 posts ago) he refers to an Infineon application note that actually discusses calibration of this sort of device.

antedeluvian
User Rank
Blogger
Re: Very much useful
antedeluvian   9/10/2013 2:42:09 PM
NO RATINGS
Sanjib

Do these devices require runtime calibration or one-time calibration in the factory before shipping?

The thought occurs to me that if you are reading the signal from the drivers you would be using and ADC and some additional circuitry, at the very least probably a resistor to convert the mirror current to a voltage. The ADC may also need some calibration, and it would be better is the whole thing was calibrated as a system. If you go to the second post before yours, you will find a pointer to part 1 of a blog I did on system calibration.

Sanjib.A
User Rank
CEO
Re: Very much useful
Sanjib.A   9/10/2013 10:48:22 PM
NO RATINGS
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!

Max The Magnificent
User Rank
Blogger
Re: Very much useful
Max The Magnificent   9/11/2013 10:53:29 AM
NO RATINGS
@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

Sanjib.A
User Rank
CEO
Re: Very much useful
Sanjib.A   9/11/2013 1:02:56 PM
NO RATINGS
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
User Rank
Blogger
Re: Very much useful
Max The Magnificent   9/11/2013 1:28:50 PM
NO RATINGS
@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.

JeffL_2
User Rank
CEO
Another approach to current monitor
JeffL_2   9/10/2013 5:34:45 PM
NO RATINGS
Just so happens I was looking for current transducers the other day, under Sensors -> Current Sensors on Digikey (notably NOT under ICs -> Linear "anything") and I have to admit I was immediately impressed at the array of actual application specific ICs available. You can get prices down around 51 cents in quantities of a few thousand for some configurations, notable vendors in the low end include Allegro Microsystems and Silicon Laboratories. I'd emphasize this is for a range up to tens of amps, if you go higher into industrial motors and such you'd likely look at something like the LEM units which are a space- and cost- saving Hall effect replacement for a current transformer but in a higher price product class. But I'd admit until I "stumbled upon" the previous class of chips I wasn't really aware of them, thought perhaps you folks might not be either, might want to go there and crack open a data sheet or two.

antedeluvian
User Rank
Blogger
Re: Another approach to current monitor
antedeluvian   9/10/2013 6:40:49 PM
NO RATINGS
JeffL

 notable vendors in the low end include Allegro Microsystems and Silicon Laboratories. I'd emphasize this is for a range up to tens of amps, if you go higher into industrial motors and such you'd likely look at something like the LEM units

I have used the Allegro hall effect parts as well as current transformers and both form a part of my arsenal. I haven't looked at LEM for a while now, I will follow your reccomendation.

 

Perhaps I should do a blog on current measurment?

David Ashton
User Rank
Blogger
Re: Another approach to current monitor
David Ashton   9/10/2013 8:30:06 PM
NO RATINGS
@asntedeluvian: Perhaps I should do a blog on current measurment?

Damn good idea!!

Brian@BDH
User Rank
Rookie
Re: Another approach to current monitor
Brian@BDH   9/10/2013 11:42:27 PM
NO RATINGS
 

@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

 

antedeluvian
User Rank
Blogger
Re: Another approach to current monitor
antedeluvian   9/11/2013 9:16:24 AM
NO RATINGS
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
User Rank
Rookie
Re: Another approach to current monitor
Brian@BDH   9/11/2013 3:58:31 PM
NO RATINGS
 

@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
User Rank
Blogger
Re: Another approach to current monitor
Max The Magnificent   9/11/2013 10:50:47 AM
NO RATINGS
@Antedeluvian: Perhaps I should do a blog on current measurment?


Yes please :-)

salbayeng
User Rank
Rookie
smart PWM "mosfets"
salbayeng   11/21/2013 7:29:49 AM
NO RATINGS
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.

antedeluvian
User Rank
Blogger
Re: smart PWM "mosfets"
antedeluvian   11/21/2013 9:42:26 AM
NO RATINGS
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!

Flash Poll
Radio
LATEST ARCHIVED BROADCAST
EE Times editor Junko Yoshida grills two executives --Rick Walker, senior product marketing manager for IoT and home automation for CSR, and Jim Reich, CTO and co-founder at Palatehome.
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed
Top Comments of the Week