PFM switching regulator circuit designs

[BlueSkyPrairie]

pfm circuit

I have subscription to IEEE Journal of Solid-State Circuits. There are a number of references on PWM circuit designs. However, I was not able to locate much reference on circuit design for the PFM (Pulse Frequency Modulation) used in switching regulator. I am aware of the paper and thesis by JinWen Xiao.
I have also search “PFM” on this website:


Gave two patent references


Hysteresis control simple circuit design !
From what I read, PFM circuit is more complex. But this hysteresis control circuit seems simple, does it work well in practical applications ?
Looks like the hysteresis control lies some of the challenges: small hysteresis may cause too much chatter/switching and losses in switching. Too big hysteresis cause error in the output.
Also PFM has constant pulse width which this circuit does not seems to have.

Would appreciate very much if you could provide more weblinks or copy of papers or thesis on PFM circuit designs.
Thank you very much.

 

[eem2am]

switching regulator circuit

PFM.......this is like the TL497 mode of operation.

PFM is also known as burst mode, and to be honest you can get the bursts happening at audio frequenccies and cause audible noise,

but it is very simple, and you dont need feedabck compensation so its easier.

it doesnt get used at higher powers because its not a smooth power flowing method, and gives too much problem with EMC, not to mention there is no "target" frequency to filter out by the emc filter.

If you find good links on this subject you are doing well.

feedback control in SMPS is more or less an industrial secret where it is known about, and you won't hear too much explanation about the finer details of hysteretic control or PFM.

If you can get away with using it, well done, its simpler than PWM with feedback control and less critical if an assembler gets a component wrong.

 

[leehying]

pfm regulator

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, VOL. 54, NO. 2, FEBRUARY 2007
An Accurate, Low-Voltage, CMOS Switching Power
Supply With Adaptive On-Time Pulse-Frequency
Modulation (PFM) Control
Biranchinath Sahu, Member, IEEE, and Gabriel A. Rincón-Mora, Senior Member, IEEE