I am modelling MAX15062 DC-DC buck converter using datasheet in PSpice, initially i worked on control loop. This buck converter has two modes PWM and PFM mode. With MODE pin unconnected works on PFM mode which changes its frequency and prevents inductor current from reaching negative at light load condition. How does it enter, sustain and exit this mode. I ran a load step analysis for MAX15062 testcase schematic designed from Maxim integrated website- downloaded the schematic and ran in EEsim (simulator).
- Here Vin=24V and Vout=5V
- Load current is varied from 300mA to 10mA
This is kept in PFM mode, where it dosent allowes inductor current to go negative by keeping highside FET and lowside FET off for some time.
It also skips some of the pulses and again recovers back and allows some pulses.
In light load condition max current is limited to 150mA.