Hi guys,
I'd like to ask you a question regarding how a detail from a sawtooth circuit works. The circuit is the following presented in the figure
![](http://s22.postimg.org/xe2tb1fwt/Untitled.jpg)
Suppose that this is already the steady-state.
The current source starts to charge the capacitor until its voltage reaches the VH. When he reaches this value the comparator toggles and the capacitor starts to discharge. Now the doubt is here: How the sawtooth starts to rise again? For example, there is another topology where one uses two comparator where each of them establishes each of the leading and trailing edges, that is, the amplitude of the comparator, when the capacitor will start to charge and discharge.
In this case, there is no second comparator to establish the low voltage threshold. So my question is, how with only one comparator, he manages to start charging again the capacitor.
Regards and thank you in advance.