output driver - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: January 16, 2016, 06:57:52 pm
content: Seems driver chips are the hardest things to find. I'm looking for an IC that has a high and low side mosfet so that I have the choice of which way to pull that is current limited. Bit like a mosfet gate driver I suppose but I'm looking for 1 or 2A so that I can safely drive a relay, 5A would be awesome

author: dadler
author_rank: Unknown
timestamp: January 16, 2016, 07:15:40 pm
content: This is just a high side driver, but ST has other similar parts that may do what you want?http://www.mouser.com/Search/ProductDetail.aspx?R=VN5E160MSTR-Evirtualkey51120000virtualkey511-VN5E160MSTR-EIs the primary requirement complementary output?

author: Simon
author_rank: Unknown
timestamp: January 16, 2016, 07:18:46 pm
content: Yea I have found loads of high or low sides but none that do both, infinion do them that can have up to 60A outputs I just want a small cheap one of these. I am trying to design something to be relatively generic so being able to switch both ways is really useful.

author: dom0
author_rank: Super Contributor
timestamp: January 16, 2016, 07:25:13 pm
content: Some time back I wanted something very similar, I basically needed a push-pull driver where I can program push-only/pull-only/push-pull/high-Z for ~30 V and a couple amps with the usual protection circuits, never found anything like it. A discrete circuit gets the job done, but doesn't scale at all for many outputs.Something like this would be really sweet. Ideally a SO-8 or something in the ballpark, as mentioned above programmable output, ideally single resistor programmed current limit for both halves and CMOS inputs independent of supply voltage. Yep.V+, GND, GND, Out, Mode [GND = push, V+ = pull, open = push-pull], Enable, In.

author: Simon
author_rank: Unknown
timestamp: January 16, 2016, 07:26:46 pm
content: they do exist look for something like TLE2505 I'm trying to find my datasheets for the powerful infinion ones. The problems is that the search terms are so generic it's hard to filter out the rubbish.

author: 128er
author_rank: Regular Contributor
timestamp: January 16, 2016, 07:34:36 pm
content: Found these a while ago for a project. But with SPI interface:MC33880http://www.nxp.com/products/discretes-and-logic/mosfets/high-side-switches/octal-serial-switch-with-spi:MC33880

author: Simon
author_rank: Unknown
timestamp: January 16, 2016, 07:37:21 pm
content: thats a bit like it, also:http://www.digikey.com/product-detail/en/TLE5206-2G/TLE5206-2GCT-ND/2231219stupid thing is if you search the infinion website for stuff it won't find it, crazy. For small power an all in one totem pole driver with current limit is the best solution in cost and space, obviously if going higher maybe go descrete but even the infinion IC's that do 40-80A are not expensive.

author: ajb
author_rank: Super Contributor
timestamp: January 16, 2016, 07:56:31 pm
content: What voltage do you need?There are some motor driver solutions that might work, particularly in the automotive voltage range. Allegro has a neat little SO8 full bridge motor driver with built-in current limiting that IIRC is rated at 2A, although keeping it from overheating at that current is challenging.EDIT: The A4950 is what I was thinking of, but it doesn't allow fully independent control of the two half-bridges, so maybe not what you're after. I'd have a look at other motor driver options, though.

author: Simon
author_rank: Unknown
timestamp: January 16, 2016, 08:00:11 pm
content: I need to work at 24V automotive so really up to 32V i will use the TLE5205 or TLE5206 as they have an output of 5A so perfect as I can drive a relay or the load the relay would have driven.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2016, 05:10:45 am
content: Ehhh... sounds like you really want an SSR.Question: are you familiar with the LM311 or 319? Would that type of output stage work for you, just bigger? ("Uncommitted switch", can be tied high or low side, or to anything between the analog supply rails.)An SSR is quite a bit slower (you didn't say what speed is needed), and much more voltage range than required for high/low side, but it's probably the simplest, cheapest, universal...est solution.Tim

author: ajb
author_rank: Super Contributor
timestamp: January 17, 2016, 05:54:01 am
content: As another option, there are some interesting isolated gate drivers that don't require a separate gate supply. Some are basically optocouplers with a big enough stack of photodiodes to produce a reasonable output voltage, but there are a couple of other options. One of those combined with a standard N-FET would essentially give you an isolated two-terminal switch that could be wired for high or a low side operation. Use a protected FET, and you've got the overcurrent protection you want as well. It won't be able to switch very fast since the available gate drive current is very low, but should be fine for a relay driver/replacement.

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 09:11:56 am
content: Quote from: T3sl4co1l on January 17, 2016, 05:10:45 amThose are opamp part numbers. Something like the TLE5206-2 is what I was after, it's only because I remembered part of the part number I found it again. Speed is not a necesity although something that can be driven with PWM would not hurt. My load is likely to che chasis grounded but a bridge output gives me all the flexibility.

author: max_torque
author_rank: Super Contributor
timestamp: January 17, 2016, 02:15:16 pm
content: There's a BIG difference between a 1A and a 5A load!!Plenty of the smaller drivers will do 1A continuously, and 5A PEAK, but you'll need proper heatsinking to use a driver at 5A continuously unless it has a suitably low RDSon!One option is to put PTC fuses in the output. If you are just driving a relay that takes <1A it's a valid option. You'll have to test to ensure the PTC "trips" before the driver goes OT.............

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 03:15:38 pm
content: Well having 5A capacity is going to be more useful as the actual load will take a couple of amps so it saves a relay. At the moment I'm trying to keep the design generic so that it can work for prototyping a number of designs. If I ever need to make a large volume I can fine tune the design.Google seems to struggle with finding these sorts of parts or maybe they are all known as motor bridge drivers as that all the manufacturer thinks you will drive with them.I'd rather avoid PTC fuses as I want to make the design quite idiot proof and not end up compromising and as far as i know they eventuall wear out.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 17, 2016, 05:03:39 pm
content: Quote from: Simon on January 17, 2016, 09:11:56 amNo, they're comparators (and the difference isn't just AC parameters this time), and I also wasn't suggesting them, I was asking. So... I take it you aren't familiar. Allow me to explain a little more.Theoutput sectionof these devices can be wired for "high side", "low side", or anything inbetween. Does that sound like what you need here? Just the output part. I'm not talking about the comparey part, or the low current part.Quote from: max_torque on January 17, 2016, 02:15:16 pmNo, this isn't an option at all, sadly. PTCs takeembarassingly longto open, even relative to ordinary fuses. And I mean the "slow blow" kind.Under fault conditions, PTCs take hundreds of ms to open. Regular fuses take 1-10ms. Semiconductors die in < 0.1ms. So you have between hundreds and thousands of transistor-blowings taking place before the PTC realizes something is amiss!If the switch is one of those nice "protected" types, then it goes into current limiting in a bit under 1ms, then it overheats and switches off (make sure to catch the inductive kick from all that extra current!). You might still use a fuse (PTC or otherwise) for reverse voltage protection, say, but that's very different.Remember: the fuse protects the wiring, the transistor protects the fuse!Quote from: Simon on January 17, 2016, 03:15:38 pmPlease, please... don't try to use Google for parts. It's just... futile. That's not the kind of thing it's made to search for.If you don't know what a thing is called, you're best off browsing either the manufacturer's categories (try TI, ST, Infineon and such; they all make parts like this), then checking back at a distributor (Digikey/Mouser/..) to see how they classify them, and then search for similar parts with useful ratings.Tim

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 05:09:18 pm
content: Well I tried infinions website and despite already knowing that these parts exist thank's to max_tourque's tip offs in the past I did not readily find them even when I brought up a list of categories. It's only because I mostly remembered the part number for the TLE5206-2 that I found it again.I don't really care who makes them, as long as I can get them. The TLE5206-2 is a nice part and will work well for prototypes that could be handled by handfisted people.

author: c4757p
author_rank: Super Contributor
timestamp: January 17, 2016, 05:10:14 pm
content: I expect a great many people to be handfisted.

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 05:12:10 pm
content: Quote from: c4757p on January 17, 2016, 05:10:14 pmWell I supplied one unit once that I'm sure worked but they said did not. I'm still not sure that they didn't short the output out and it was just a dual BJT pair in totem pole configuration. So to supply something that is to drive a couple of amps without any protection would be unwise.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: January 17, 2016, 05:34:28 pm
content: i don't think i really understand what you looking for, but if it's kind of half bridge ? and close to TLE 5206-2 , may i suggest the old L298 , there is 2 independent H bridge , so you can use a half one from each one.For the protection i remember Mike (mikeselectronicsstuff) used some power regulator with rapid overload protection (nano second reaction ) for one of his project, you may power the H-bridge of the L298 with it and it will shut-down when over loaded.

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 05:35:46 pm
content: Well the TLE5206-2 is quite what I want, it's just the bugger of finding parts you have forgotten the part number of.

author: dom0
author_rank: Super Contributor
timestamp: January 17, 2016, 05:51:18 pm
content: QuoteGoogle is bad at finding parts, but the categories on the manufacturer pages are often ... questionable at best. I remember the LM3xxx linear audio amps being in the "mid power Class D audio amplifiers" (or so) section on the TI page.Sometimes parts are seemingly not categorized at all and simply don't show up in categories or parametric searches, only being found by directly going to their parts page or searching for the part number.My gut feel is that the large distris keep better order, but categories are usually broad and the "function" (or similar) column often has a huge number of choices, making it likely to miss many parts again...It's still easier today with many many more parts than a few decades ago, no thick paper books and of course 25 years ago one couldn't have known about any part not listed in the books you have... so, things are of course better than yesteryear, but still a lot of room for improvement...

author: fcb
author_rank: Super Contributor
timestamp: January 17, 2016, 06:18:30 pm
content: What about the humble L298 by ST?

author: Simon
author_rank: Unknown
timestamp: January 17, 2016, 06:19:18 pm
content: It's not cheap (£5+) and has no short circuit protection.

author: c4757p
author_rank: Super Contributor
timestamp: January 17, 2016, 06:37:39 pm
content: Quote from: fcb on January 17, 2016, 06:18:30 pmOne of the most pointlessly horrid elderly chips still being manufactured. Why do they even still bother making them? They suck ineveryspecification and cost a lot.Simon, it's "ham"fisted, everybody's fist is a hand.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: January 17, 2016, 07:12:20 pm
content: Quote from: c4757p on January 17, 2016, 06:37:39 pmwhile i never used for any deliverable project, i used it to build many application around motors and for a single application to step-up voltage using transformer , most of those app i used them in the lab , never failed once. So i don't see why you considered as pointless

author: c4757p
author_rank: Super Contributor
timestamp: January 17, 2016, 07:32:29 pm
content: I said "pointless", not "useless" - theydosomething, sure, and you can use them for that thing. But when others exist that areboth better and cheaper, what is theirpurpose?

author: dom0
author_rank: Super Contributor
timestamp: January 17, 2016, 07:35:34 pm
content: 1:1 legacy replacements and DIY people who don't know better.A bit like bipolar 555s.