Zero current detector of Buck regulator

[mitgrace]

zero current detector

Dear All :

Does anyone have any sense about this circuit ? Or Does anyone have this document or paper .

 

[tsanlee]

zero current detection

Current Mode or Voltage mode buck Reg??
Direct current densing or peak current sensing ??

 

[mitgrace]

uc384x buck

I work on current and volatge mdoe . What is beeter ??Direct current densing or peak current sensing ?? Actually i don't have sense , Can you give me some suggestion ?

 

[huojinsi]

current zero detector

Usually,the PFC circuit includes zero current detector.About zero current detector of buck regulator,u can consult UC384X series. Maybe it will give u help.

 

[yeewong_su]

buck pfc circuit

Using the sense resistor and sen amplifier

 

[andy2000a]

l6562 inductor

another PFC or applicatio note is L6561 L6562
ML4800 , PFC detect zero current use "sense resistor" and detect from 1.3~ 2.6v , many chips
have many speci on "zero" Voltage

another is use BJT process cross Zero detect by
BJT Vbe

 

[mitgrace]

buck nmos light load

DOes anyone have good paper ? I looking for some paper , But I can't work it by simulation . DOes any reference circuit for Zero detector , Thanks

Added after 4 minutes:

Dear All :

I work On DC/DC buck regulator , I eadr some paper , It sense the lx and grond , Then sent the MNoff signal , But it is a structure diagarm , DOes anyone have the real circuit , Thanks

 

[babbage]

buck regulator zero location

In fact, this circuit is not difficult to design. You can make use of the Nmos ON resistor or sense resistor to sense the current signal of Nmos.
Maybe what you should consider is the zero threshold. You shift the dc level of sense signal to Vbe or one constant value. Then everything is ok!

 

[mitgrace]

buck regulator circuit

I have done the zero cuurent detector now , I test the top simulation , I found in the ligh low , the efficieny is bad . I check the frequency is very high (160k) , The PWM is 300k , How do I implement the good PFM structure ? In the different conversion rate (3 to 1.2 / 3 to 1.8) , The efficiency is very different , How can I improve it ? Thanks

 

[adam79416]

zero location buck regulator

good topic. Very good.

 

[babbage]

dc-dc zero current detect

I don't clearly understand your PFM structure. But I believe there are some questions about your zero current detector.
In fact, zero current detector's threshold can be not zero because there is some delay time about this circuit. During the delay time, the inductor current will be flow from cap to Nmos. This power dissipation is so important in the light load.
Maybe you can modify this circuit' zero thershold to be one negative threshold. Then when the inductor current is not reduced to zero, close the Nmos. Of cource how much is this threshold of this circuit? It should depend on your zero current detector respons time.

Added after 5 minutes:

Of cource if there is no problem about zero currrent detector, I think maybe the question is mainly PFM structure.
If you do the efficiency analysis for your PFM, I believe you can find the real cause.