InnoSwitch3-EP ILIM Dependency on Frequency
Hi.
Figure 6 of InnoSwitch3-EP datasheet shows the normalized ILIM dependency on frequency and the related text says: "The primary-side controller has a current limit threshold ramp that is linearly decreasing to the time from the end of the previous primary switching cycle (i.e. from the time the primary MOSFET turns off at the end of a switching cycle)."
My question is about the related linear reduction of ILIM. Could you inform this reduction rate in function of the time from the MOSFET turning off? (Considering the referred text, I suppose this reduction rate could be a better way of ILIM prediction than the frequency, on witch the graphic of figure 6 is based.)
Regards.
Christos
Comments
Hi
As the switching period changes Toff also changes. They both are inter related.
So yes, as the switching frequency changes current limit of the device as shown in Figure 6 of the datasheet.
Regards,
PI-NANO
Thank you, PI-NANO.
The only "problem" is the datasheet says the current limit depends linearly on TOFF time and, instead, it depends linearly on the PERIOD time.
I think the related text of the datasheet needs a correction...
By several project simulations in PI Expert with INN3677C, I noticed that the current limit reduction rate is linearly related to the switching PERIOD and NOT to the Toff time, according to the datasheet text quoted above. This makes the graphic of figure 6 a good way of predicting ILim.