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Hello again,
One thing i forgot to mention is that a true power converter (such as a buck) will usually mean higher efficiency, but because converters are not 100 percent efficient either there is a break even point where the efficiency of a pure PWM circuit is the same as that of a buck circuit.
For a quick example...
If we had 6 volts input and 5 volts output with a load of 5 Ohms with a buck circuit with 90 percent efficiency, the efficiency would of course be 90 percent. With a pure PWM at 100 percent duty cycle and the same load and output and output voltage requirements we would need a 1 Ohm resistor in series. The efficiency would be about 83 percent. This in this case the buck beats the pure PWM.
However, if we we working with a 5.555555 volt input, the resistor Rs can be decreased to 0.555555 Ohms, meaning the efficiency goes up, and in this case it goes up to 90 percent.
So we can see how the input voltage and output voltage matching plays a part in the decision what kind of PWM to use, either pure PWM or an actual true power converter.
The above was just one simple example but we could look at other examples too.
An even simpler example would be we have 5v input and we want 5v output. Obviously we dont need a converter.
You could check other duty cycle values too.
One thing i forgot to mention is that a true power converter (such as a buck) will usually mean higher efficiency, but because converters are not 100 percent efficient either there is a break even point where the efficiency of a pure PWM circuit is the same as that of a buck circuit.
For a quick example...
If we had 6 volts input and 5 volts output with a load of 5 Ohms with a buck circuit with 90 percent efficiency, the efficiency would of course be 90 percent. With a pure PWM at 100 percent duty cycle and the same load and output and output voltage requirements we would need a 1 Ohm resistor in series. The efficiency would be about 83 percent. This in this case the buck beats the pure PWM.
However, if we we working with a 5.555555 volt input, the resistor Rs can be decreased to 0.555555 Ohms, meaning the efficiency goes up, and in this case it goes up to 90 percent.
So we can see how the input voltage and output voltage matching plays a part in the decision what kind of PWM to use, either pure PWM or an actual true power converter.
The above was just one simple example but we could look at other examples too.
An even simpler example would be we have 5v input and we want 5v output. Obviously we dont need a converter.
You could check other duty cycle values too.
