Contents
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’s the maximum DC voltage for an optocoupler circuit?
ISOLATION VOLTAGE. This is the maximum permissible DC potential that can be allowed to exist between the input and output circuits. Typical values vary from 500V to 4kV. VCE(MAX). This is the maximum allowable DC voltage that can be applied across the output transistor. Typical values vary from 20V to 80V.
How is the optocoupler connected to the TTL?
Here, the optocoupler LED and current-limiting resistor R1 are connected between the 5V positive supply rail and the output-driving terminal of the TTL device (rather than between the TTL output and ground), because TTL outputs can usually sink a fairly high current (typically 16mA) but can source only a very low current (typically 400µA).
What are the different types of optocoupler devices?
The Figure 2 device is a simple isolating optocoupler. Figures 3 and 4 show two other types of optocoupler. 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.
What is the voltage of an optocoupler gate?
Assuming that a single HCT output is only feeding this optocoupler, a logic 1 voltage of about 4.9V can be presumed. The output current available from a HCT gate to drive the optocoupler input is limited to 4mA, which is quite low for driving an optocoupler.
What can an optocoupler do for a computer?
There are of course, more useful applications for an optocoupler than simply isolating one logic IC from another. A common problem is driving a load from a computer’s output port. Computers are expensive and easily damaged by mistakes made when connecting them to external circuitry.