If you want to design for high speed capability of PWM controller, which includes an oscillator frequency range to 1MHz and total propagation delays less than 100ns you may see the typical application circuit below using LM5020 in the following datasheet.
The LM5020 provides all of the advantages of current-mode control
including line feed-forward, cycle-by-cycle current limiting and
simplified loop compensation, according to the datasheet.
The LM5020 includes a high voltage pulse-width-modulation
(PWM) controller which has all of the features needed to implement
single ended primary power converter topologies. It also has a high
voltage start-up regulator that operates over a wide input range up to
100V. This device is used to be applied on telecommunication and
industrial power converters, and/or +42V Automotive Systems.
In the LM5020 datasheet, you will find sections such LM5020 Connection Diagram and pin descriptions, the functional block diagram
of the device, line Under Voltage Lock Out (UVLO) circuit, an internal
high gain error amplifier, a cycle-by-cycle over current protection
function, sets the LM5020 oscillator frequency, and The LM5020 duty cycle limit options. You may read on complete explanation about this High Speed-Voltage PWM Controller Device in the datasheet (source: national.com)