H bridge types

[javafiend]

Can anyone tell me the difference between a half h-bridge, full h-bridge, and dual h-bridge?  More specifically, what they're capable of and why they're named like they are.

Appreciate it, thanks!

[Webbot]

My understanding is:
1. A half H bridge controlls one motor lead
2. A full h-bridge controlls two motor leads - and hence one 'full' motor
3. A dual-hbridge controlls two 'full' motors

[izua]

half h bridge is what the industry refers to a push-pull driver. this kind of thing can both source and sink. easiest to think of it is a npn and a pnp, with bases in parallel and emitters shorted.
a full bridge has two push-pull drivers. turning one to sink and one to source yields a motor direction, reversing their logic reverses motors directions. used to reverse current direction.

a dual h bridge has two h bridges, or four push-pull stages.

[javafiend]

So if I wanted to run 2 basic DC motors of a differential drive robot I would need a dual h-bridge, correct?  Is this what other folks use?  Also, what other options are there?

[sonictj]

your options are dependent on your application. 


If you just want to drive two small motors (1-2 amp) I would recommend an l298 dual h bridge.  I just built the circuit last night and it works great.  I like the l298 because it is versatile.  My purpose for using it was to drive a bipolar stepper motor but I can also use it to drive 2 dc motors instead .  The chip is a tad difficult to solder but its not too bad.

For bigger motors I use a sabertooth 2x10 from dimension engineering.  The thing was a bit pricey, but it has tons of features that I can use for all my future robots. 

hope that helps

[Webbot]

So if I wanted to run 2 basic DC motors of a differential drive robot I would need a dual h-bridge, correct?  Is this what other folks use?  Also, what other options are there?

Checkout my motor driver tutorial for various circuits:
http://www.societyofrobots.com/member_tutorials/node/159

[ArcMan]

Wikipedia has a good short description of H-bridges.

http://en.wikipedia.org/wiki/H-bridge

I'm partial to the LMD18200 H-bridge IC.  It uses MOSFETs so it doesn't get really hot like the L298 (which uses bi-polar transistors and provides a significant voltage drop to the motor).  It also has built in flyback diodes, so you don't need external diodes like with the L298.  The disadvantage is that there is only 1 H-bridge per package, whereas the L298 has 2 (a dual H-bridge).  This makes the L298 cheaper to use.  So I recommend the LMD18200 for 2 or 3 amp loads and the L298 for smaller loads like 1A or less.

[javafiend]

Checkout my motor driver tutorial for various circuits:
http://www.societyofrobots.com/member_tutorials/node/159

On the 600mA version you mention using the SN754410.  After Googleing the part it calls it a Quad Half H-Bridge IC.  I have no clue what that means, but I'm going to assume that it's a dual h-bridge (4 half h-bridges).  However, I wasn't quickly able to find a simple diagram for using it.  Now notice I said "simple."  Is there anything like Admin's $50 robot tutorial for building an h-bridge with or without that IC?

[Webbot]

The SN754410 is a pin-for-pin replacement of the L293D - so you can use my L293D circuit diagram and choose which of two chips you want to use - there are NO changes. The SN754410 tends to be cheaper to buy and can provide a slightly higher current.

The SN754410, just like the L293D, is a Quad Half H-Bridge. Each 'Half' drives one motor wire. 'Quad' means 'x4' -  so it can control 4 motor wires - ie 2 DC motors.

You can download the SN754410 datasheet here http://www.datasheetcatalog.com/datasheets_pdf/S/N/7/5/SN754410.shtml

[Webbot]

Wikipedia has a good short description of H-bridges.

http://en.wikipedia.org/wiki/H-bridge

I'm partial to the LMD18200 H-bridge IC.  It uses MOSFETs so it doesn't get really hot like the L298 (which uses bi-polar transistors and provides a significant voltage drop to the motor).  It also has built in flyback diodes, so you don't need external diodes like with the L298.  The disadvantage is that there is only 1 H-bridge per package, whereas the L298 has 2 (a dual H-bridge).  This makes the L298 cheaper to use.  So I recommend the LMD18200 for 2 or 3 amp loads and the L298 for smaller loads like 1A or less.

Just for info: if you get the L293D then it DOES contain the external diodes.