Dear Experts,
I am using TI auto DCDC chip LM25011 for the power solution, the phase node looks like unstable in 12V input, the design requirements is as below:
1) Input range: 8V~30V, the nominal input is 12V
2) Output voltage: 5V
3) minimum load voltage 250mA, nominal current is 300mA, max current is 500mA
4) SW: 900K
the schematic and component selected value, please see the shecmatic screenshot below
when 12V input, I probe the phase node, there is some unstable waveform, the chip is not the continouse PWM mode, but looks like not uncontinous mode too, it looks like some unstable waveform on the phase, I have no FRA equipement to check the compensation. when I increase the input voltage to 15.4V and bigger, the phase node is in the continouse PWM mode, should work normally.
Please see the phase node waveform of 12V input
please see the phase node waveform of 15.34V input
Please guide me whether the phase node performance is nomal when 12V input? how could I design the chip to work at continous PWM mode when 12V input?
Thanks and Best regards,
Larry
