Part Number: LM5148
Other Parts Discussed in Thread: LM5137, LM5145
I need to design a 4-phase interleaved buck power supply with wide output range (0~0.98*Vin) using LM5148, the synchronization clocks are generated from an additional MCU and input to LM5148's PFM/SYNC pin.
I have noticed that when operating in secondary mode, LM5148's switching frequency will track the external clock instead of the internal oscillator, and RT pin resistor is only used for adjusting the slope compensation.
According to LM4158 datasheet, the RT pin is regulated to 0.5V, and the switching frequency changes almost linearly to Rrt, so I indicate that the compensation slope is proportional to the current sourcing from RT pin.
The question is:
Can I apply an adjustable current sink (assuming proportional to Vout) to RT pin to control the sourcing current and further control the slope compensation? So that the sub-harmonic oscillation can be prevented in the required wide output range, especially when D>50%.
Thanks!
Best Regards,
Liu
