Is there such a thing as a reverse optocoupler?

Is there such a thing as a reverse optocoupler?

Is there a reverse optocoupler, i.e. “turn on irLED, unknown component is triggered and stops/blocks current flow”, an optical on then off switch? Circuit A does something that includes a charging function then activates Circuit B.

What is the basic function of an optocoupler?

Ok, I know the basic function of an optocoupler is “turn on irLED, triggering a phototransistor and allowing current to flow”; an optical off then on switch. Is there a reverse optocoupler, i.e. “turn on irLED, unknown component is triggered and stops/blocks current flow”, an optical on then off switch?

What is the CTR of a Darlington optocoupler?

Because of the high current gain of the Darlington, this coupler has a typical minimum CTR value of about 300%, but has a useful bandwidth of only 30kHz. The dual and quad optocouplers of Figure 7 use single-transistor output stages in which the base terminal is not externally available.

What do you call a slotted optocoupler circuit?

The device shown in Figure 3 is known as a slotted optocoupler, and has a slot molded into the package between the LED light source and the phototransistor light sensor. Here, light can normally pass from the LED to Q1 without significant attenuation by the slot.

What is the forward current of an optocoupler?

It consists of collector-emitter voltage (VCE) and collector current (IC) as a function of the base current (IBASE). With optocouplers, the emitter forward current (IF) is approximately equivalent to the transistor’s base current (IBASE) and is plotted as forward current (IF) in various steps.

What kind of RX unit does an optocoupler use?

Most modern optocoupler devices use a phototransistor as their Rx unit; such a device is known simply as an ‘optocoupler,’ since the input (the LED) and the output (the phototransistor) devices are optically coupled. Figure 2 shows the basic form of an optocoupler, together with a very simple application circuit.

How to calculate optocoupler efficiency in a circuit?

The most convenient way of specifying optocoupling efficiency is to quote the output-to-input current transfer ratio (CTR) of the device, i.e., the ratio of the output collector current (I C) of the phototransistor, to the forward current (I F) of the LED. Thus, CTR = I C /I F.

What kind of circuit is an optocoupler circuit?

FIGURE 2. Basic form and application circuit of a typical optocoupler. Most modern optocoupler devices use a phototransistor as their Rx unit; such a device is known simply as an ‘optocoupler,’ since the input (the LED) and the output (the phototransistor) devices are optically coupled.

How does an infra-red light work in an optocoupler?

Current from the source signal passes through the input LED which emits an infra-red light whose intensity is proportional to the electrical signal. This emitted light falls upon the base of the photo-transistor, causing it to switch-ON and conduct in a similar way to a normal bipolar transistor.