a questiong about DC-DC convert.

[mayichao]

i think when a dc-dc convert works at discontinue mode , the switch
state is on-> off -> another off ->on ->off .....
but i use the ltspice it tell me lt1316's worke state is on->off->on-

off(servel this state)->a long time off->on->off->....

(i am sorry i can not post my picture on the group )
http://fbbs.ustc.edu.cn/cgi/sf?s=37adaef4&bn=Circuit&fn=M49BF1EA3&an=ltc.jpg
So the question is how to measure the Duty cycle?

 

[mayichao]

i am sorry.
i think i should change a link at once.

 

[mayichao]

thanks for your help.
please try this link.
http://mail.ustc.edu.cn/~ycma/ltc.jpg
green trace is Vsw
and the blue trace is I on inductor.

 

[mayichao]

if you have an LTspice , you can open the test fixture.
The state i want description is that.

 

[Eeyore]

thanks for your help.
please try this link.
http://mail.ustc.edu.cn/~ycma/ltc.jpg
green trace is Vsw
and the blue trace is I on inductor.

That's 'burp mode'. Different to continuous / discontinuous operation despite what it
sounds like.

I assume that was at low load.

Graham

 

[Eeyore]

if you have an LTspice , you can open the test fixture.
The state i want description is that.

I've never managed to get my head around LT Spice I'm afraid. Poor user interface ?

Graham

 

[mayichao]

dear Graham
LT1316 worked on 'burp mode' , and it works normally.
I want to measure the duty cycle.
in this picture
http://mail.ustc.edu.cn/~ycma/ltc.jpg
dutycycle is what?
i think i should learn more about burp mode.

 

[Jamie]

mayichao wrote:




This just gives me a 'refer error'.

Graham

Well that answers it, must of been a "discontinuous mode", hence the
vanishing of the sight.

http://webpages.charter.net/jamie_5"

 

[Jamie]

mayichao wrote:




I've never managed to get my head around LT Spice I'm afraid. Poor user interface ?

Graham

I have no problems with it! fully comprehensible to me. Must of been
designed for those like me! Sorry you're left out in the cold, its a
beneficial handy tool..


http://webpages.charter.net/jamie_5"