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An H-Bridge is a circuit of 4 switches allowing to select the direction of current flowing through a part. The simplest H-Bridge consists of four manually controlled switches | An H-Bridge is a circuit of 4 switches allowing to select the direction of current flowing through a part. The simplest H-Bridge consists of four manually controlled switches. The name is derived from the circuit diagram which looks like a capital H. | ||
When using | When using an H-Bridge it is important to prevent switches to short circuit the supply voltage. In a few H-bridge designs additional circuitry prevents accidental short circuits, but most available chips don't have this protection. | ||
[[File:H-BridgeLeftRight.png]] | [[File:H-BridgeLeftRight.png]] | ||
== | Often "Half-bridges" are used where you'd expect an H-Bridge. They are almost the same - but only the left (or right) part of the Bridge is already connected. (2 switches in series with their middle as output. Out of two half-bridges you can build an H-Bridge (also often referred to as Full-Bridge). | ||
== Use == | |||
* H-Bridges are often used to switch [[DC motor]]s in speed and direction. | |||
* Generate AC-Currents where AC is needed. | |||
* Turn a bi-stable relay on/off | |||
* Dual-H-Bridges (or quadruple half bridges) Are useful to control bipolar [[stepper motor]]s | |||
== Popular H-Bridges and Half-Bridges == | |||
L293D quad half-bridge: one of the cheapest part to build one or two H-Bridges. Has built in diodes, comes in a standard DIP package: conveniently useable in a Breadboard. 600 mA continuous current. | |||
SN754410: built in free wheeling diodes, DIP package - very similar to the L293D but more power (1.1A per channel) and allowed pwm frequencies are higher. According to its dataseheet the SN754410 is usable as a replacement for the L293. (even better). | |||
L298N: Well known and widely used Dual H-Bridge (2 H-Bridges in One IC). Comes as Powerdip IC - doesn't fit into breadboard without modifications. 2 A continuous current. Even if it's designed to be an H-Bridge it has no additional logic preventing shorts. | |||
== Links == | |||
* [http://www.bobblick.com/techref/projects/hbridge/hbridge.html H-Bridge using darlington Transistors - 5A] | |||
* [http://www.armory.com/~rstevew/Public/Motors/H-Bridges/Blanchard/h-bridge.htm The Armory] Figure-1 shows a circuit of an h-bridge using MOSFET transistors. | |||
* [http://wiki.ctbot.de/index.php/L293D German Tutorial, connecting 2 Motors to an L293D] | |||
* [http://itp.nyu.edu/physcomp/Labs/DCMotorControl English Tutorial, connecting one Motor to an L293D] | |||
* [http://www.mikrocontroller.net/articles/H-Br%C3%BCcken_%C3%9Cbersicht Circuit of an H-Bridge entirely made of discrete components like transistors, free wheeling diodes] | |||
[[Category:Electronics]] | [[Category:Electronics]] | ||
[[Category:Martin Schied]] | [[Category:Martin Schied]] | ||
[[Category:Motor]] | |||
Latest revision as of 13:51, 9 January 2013
An H-Bridge is a circuit of 4 switches allowing to select the direction of current flowing through a part. The simplest H-Bridge consists of four manually controlled switches. The name is derived from the circuit diagram which looks like a capital H.
When using an H-Bridge it is important to prevent switches to short circuit the supply voltage. In a few H-bridge designs additional circuitry prevents accidental short circuits, but most available chips don't have this protection.
Often "Half-bridges" are used where you'd expect an H-Bridge. They are almost the same - but only the left (or right) part of the Bridge is already connected. (2 switches in series with their middle as output. Out of two half-bridges you can build an H-Bridge (also often referred to as Full-Bridge).
Use
- H-Bridges are often used to switch DC motors in speed and direction.
- Generate AC-Currents where AC is needed.
- Turn a bi-stable relay on/off
- Dual-H-Bridges (or quadruple half bridges) Are useful to control bipolar stepper motors
Popular H-Bridges and Half-Bridges
L293D quad half-bridge: one of the cheapest part to build one or two H-Bridges. Has built in diodes, comes in a standard DIP package: conveniently useable in a Breadboard. 600 mA continuous current.
SN754410: built in free wheeling diodes, DIP package - very similar to the L293D but more power (1.1A per channel) and allowed pwm frequencies are higher. According to its dataseheet the SN754410 is usable as a replacement for the L293. (even better).
L298N: Well known and widely used Dual H-Bridge (2 H-Bridges in One IC). Comes as Powerdip IC - doesn't fit into breadboard without modifications. 2 A continuous current. Even if it's designed to be an H-Bridge it has no additional logic preventing shorts.
Links
- H-Bridge using darlington Transistors - 5A
- The Armory Figure-1 shows a circuit of an h-bridge using MOSFET transistors.
- German Tutorial, connecting 2 Motors to an L293D
- English Tutorial, connecting one Motor to an L293D
- Circuit of an H-Bridge entirely made of discrete components like transistors, free wheeling diodes