I need help for Optocoupler

function of optocoupler

Hello everyone.

Could somebody explain to me the function of optocoupler? When to use Optocoupler? and the sample schematic diagram on how it is being used?

Thanks.

optocoupler function

Opto coupler is used to isolate two circuit supplies, and to protect sensitive circuits from spikes, surges & noise that comes from an inductive loads ............

optocoupler schematic

Have you looked at the wikipedia article? It explains what optocouplers are and gives an example circuit. Also, check out the links at the bottom of the page for more information.

function optocoupler

schematic diagram

avago wide body optocouplers quality

Thank you for the quick response. It really helps.

schematic logo for an optocoupler

I used this circuit to remotely (wirelessly) turn on a computer with an AVR micro. The computer's on/off switch is wired through the opto.

I pulled the opto off an old power supply I had lying around.

Good Luck

optocoupler example circuit

There are two main reasosn to use an optcooupler:

- Insulation: The physical seperation of HV circuit from LV one. Typical applicaiton is motor control, where DC BUs for power transistors are several hundred volts whereas controller is on 3V/5V levels. It is for safety of LV side and (if existing) end user. You can imagine what happens if there is no isolation barrier and you touch to the system. Optocouplers are approved, therefore, for safe/reinforced insulation. Even if the IC inside is broken down, input and output sides will be still insulated. One interesting part is widebody packages from AVAGO like ACNW3190. It has output up to 5.0A, whereas can insulate 5kVrms for 1min, or 1414V for continuous working voltage.

- Isolation: Here the improvement of signal quality is acvhieved. During swtiching of power transistors there will be high amount of dv/dt transients (e.g. 1.5kV common mode in 100ns). Such transients can be also due to inductance in the system. Such transisnet will not only instabilize LV signal shaping, but also can really strike LV components and make them damaged. Optocoupler prevents that with seperation of two sides. Another good point for CMR performance is in indsutrial comm systems (e.g. RS-485, Profibus, CANBus etc.). Here you connect two end modules to each other with long cables. The grounds of two moduels will be different and thus gorund loop can happen. An optoocupler will prevent it due to seperation. Also it will eliminate again transeints coupled into the system.


Hope it helps.

Cheers

optocoupler ic wikipedia

Thank you hakeen. It's very enlighthening. It really helps.

can a optocoupler be used as a on/off switch

Traic and SCR are also used at optocoupler, because they are cheep and faster.