The TPS568215 operates using the adaptive on-time PWM control with a proprietary D-CAP3™ control which
enables low external component count with a fast load transient response while maintaining a good output
voltage accuracy. At the beginning of each switching cycle the high side MOSFET is turned on for an on-time set
by an internal one shot timer. This on-time is set based on the converter’s input voltage, output voltage and the
pseudo-fixed frequency hence this type of control topology is called an adaptive on-time control. The one shot
timer resets and turns on again once the feedback voltage (VFB) falls below the internal reference voltage (VREF).
An internal ramp is generated which is fed to the FB pin to simulate the output voltage ripple. This enables the
use of very low-ESR output capacitors such as multi-layered ceramic caps (MLCC). No external current sense
network or loop compensation is required for DCAP3™ control topology.
PWM控制模式的原理是不是，由内部定时器来决定上管的Ton，内部定时器由输入输出电压和工作频率决定，也就是占空比。
然后当上管的Ton结束后，上管关断，下管导通，电感释能，输出电压减小，FB脚电压减小，当FB脚电压低于误差放大器的参考电压时，内部定时器重新计时工作。
然后产生一个内部斜坡反馈到FB脚来模拟输出电压纹波？
这个是我的理解，不知道对不对，然后就是那个内部斜坡是怎么模拟输出电压纹波的就不是很懂了。
