differences/advantages/dsadvantages between the L293D and the H-bridge??? please help

hey,

i need to know the difference/advantages/dissadvantages (if you can help with any of these please do) between the H-bridge and the L293D

i know almost nothing except the L293D is just like a dual H-bridge.....

please help

thankyou very much in advance

An H-bridge is an H-bridge is an H-bridge.

The L293D is a quad half H-bridge chip which means you can make 2 complete H-bridges out of it. Perfect for bipolar stepper motors. I assume when you compare it to a normal H-bridge, you are talking about discrete components. The advantage of the L293D is it will be much easier to hook up. The advantage of a discrete solution is you can configure it to handle just about any amount of power you need.

your question is like asking "what's the difference between an automobile and an Audi 4000".

First off, you need to give more complete information. You say "the H-bridge". is there a specific one you are looking at in addition to the L293D? also, the motor current is a huge factor in selecting an H-bridge (or building one from scratch) - you really need to know it before going any farther.

I suggest the first thing to do is get datasheets for all the chips you are looking at. it may seem like a foreign language but it's one you should learn.

when you know the motor current, you can determine if a specific H-bridge is appropriate. The L293D is spec'd up to about 1A but I wouldn't do that continuously for more than 10-15 seconds max. It's going to get very hot otherwise.

I actually find a lot of H-bridges harder to hookup (too lazy to read the datasheet and figure out it out) and try to use discrete components for if possible. It's just that the datasheet seems to make it so much more complicated to hook up when you know how simple the H-bridge is. They also tend to be too low current, have a crummy/ackward/unwieldly control scheme, and too many useless features which all make it more complicated to hook up while getting nothing in return. I usually build my own discrete H-bridge and construct a motor-controller around it (or buy a motor-controller board) rather than using an H-bridge IC and building a motor controller around that. THat way, I get tend to get a minimalistic H-bridge that can handle more power, has only the features I need and a control scheme of my liking.

There's only one H-bridge chip I have ever considered using and that's the 30A Automative H-bridge IC from ST Microelectronics. Because it has built in voltage/current/thermal/protection, high current and a current sense output and some fault detection stuff which are all really useful while being really straightforward to hook-up- makes it more like a PCB-based motor controller that just an H-bridge chip.

Hmm, the VNH2SP30 ... 12V, 30A, and cheap. 5V CMOS thresholds - bleh. But considering they seem to be using pretty beefy mosfets instead of some ancient bjt's in the thing - total series impedance of 19mOhm... I think I'll need to have some of those in my parts bin.

hmmm...i see well thankyou, but i am really looking for a bunch of H-Bridges compared to each other..anyone? anyone?

if you cannot answer this question for me, do you know of any sites that compare typest of different H-Bridges?

thankyou,

I would guess there are about 10-15 companies which make h-bridge chips. Each company has a product line with 5-15 h-bridge parts. There is a horrendously large number of parts out there - and it changes every few months as new better parts get introduced.

When trying to look for parts, I typically go to my distributor websites and do a generic search for "h-bridges", just to get a list of vendors which have these kinds of parts. Then go directly to the vendor website and dig through all the parts. It is tedious, and confusing, but it is a pretty important part of a EE's job.

I'm sure a lot of people on this board would be pretty helpful in describing specific differences between specific parts, but as for a generic up-to-date comparison page, I've never seen one.

hjames said:

Hmm, the VNH2SP30 ... 12V, 30A, and cheap. 5V CMOS thresholds - bleh. But considering they seem to be using pretty beefy mosfets instead of some ancient bjt's in the thing - total series impedance of 19mOhm... I think I'll need to have some of those in my parts bin.

Click to expand...

Yeah, those were the ones I was talking about.. pretty nice as far as H-bridge ICs go? What's wrong with 5V CMOS thresholds? You working with 3.3V DSPs? Makes it a lot more convenient to build a 15-30A motor controller.

Nearly all the stuff I do is in 3, 3.3V land. I'm actually starting to consider 1.8V as my "standard "core" voltage for some of my (work) projects. Mainly for battery efficiency considerations - CMOS dissipation goes up with the square of the voltage, so dropping voltage by that much means lower current draw/longer battery life.

Yeah I hate logic level translation too. All my complex algorithm processors use 3.3V, except for the one 5V processor I use to interface directly with hardware like H-bridges.