Cabraham I am very grateful for your reply which makes a lot of sense to me.
Its strange that some Boost converter LED driver chips have datasheets that recommend using frequency compensation, some recommend adding slope compensation, -but some make no such recommendations….
Please see (if you wish) the ZXCS400 datasheet (Boost LED driver)
*****ZXCS400 DATASHEET
This chip (ZXCS400) does not have an oscillator and appears to use hysteretic mode.
Many LED driver chip datasheets say that hysteretic mode controllers do not need any frequency compensation or slope compensation .
If hysteretic mode controllers are devoid of the RHPZ problem, then I wonder why they are not far more common ?
The LM5022 Boost LED driver has facility for compensation components to get round the RHPZ problem (bottom of page 6, datasheet)
****LM5022 DATASHEET
The TPS61160 is a Boost LED driver that somehow manages to avoid the RHPZ by simply adding a 220nF compensation capacitor in all cases. (please see middle of page 15, TPS61160 datasheet)
*****TPS61160 DATASHEET
Coming back to voltage mode boost converters, the TL497 is a constant on-time SMPS controller and none of the boost application circuits in the datasheet have any frequency compensation components. In fact, the TL497 has no error amplifier, but instead just has a comparator, so I am, wondering how TL497 boost converters get around the RHPZ?
***TL497 DATASHEET
Also, Quoting from page 10 (under “Theory of operation”) of the LM3404 Buck driver datasheet..........
“Hysteretic operation eliminates the need for small signal control loop compensation.”
*******LM3404 DATASHEET
Is it true that hysteretic mode boost converters have no Right Half Plane Zero problem?
Also, is it possible to have a fixed frequency, hysteretic converter?
Thankyou for reading.