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How to calculate the PWM of an optocoupler?
A quick calculation can be made if you know the frequency of the PWM (F PWM) and the rise time (t R) and fall time (t F) of the optocoupler: F PWM = 2/n (t R +t F ), where n is the number of discrete steps that the optocoupler can accommodate. Solve for n:
What kind of light does the optocoupler use?
The optocoupler translates the signal on its input into an infrared light beam using an infrared light emitting diode (LED).
How are optocouplers used in power supply regulators?
Optocouplers are used in power supply regulators, as protection for inputs to microprocessors and other sensitive devices, and in many more applications.
How many steps can an optocoupler handle at 2kHz?
Solving for n gives us 7,692 steps. Therefore, this optocoupler can resolve 7,692 steps from a PWM running at 2kHz. If you have a 10-bit PWM, which has 1024 steps (2 10 =1024), this high-speed optocoupler would be overkill since the optocoupler can handle over 7,000 steps at that PWM frequency of 2kHz.
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 kind of current does an opto coupler need?
As the current available from typical computer input/output ports may only be a few µA, as computer port lines are usually designed to drive some type of logic input, the input to this motor drive circuit is via a HCT Schmitt inverter gate, which only requires an input current of 1µA, with the 12V 40mA motor being driven by a 2N3904 transistor.
How is an optocoupler used in the design process?
The start of the design process is to specify the input and output conditions the optocoupler is to link. Typical optocouplers can handle input and output currents from a few microamps to tens of milliamps.