johnme 發表於 2014-4-5 00:33 static/image/common/back.gif
Sounds great, I will ask you for the polyester caps later.
Here is a modified version.
yup, i'll free u some Panasonic polyester caps when I'm home. {:1_351:}
billymud 發表於 2014-4-5 01:04 static/image/common/back.gif
yup, i'll free u some Panasonic polyester caps when I'm home.
what value do you have?
billymud 發表於 2014-4-5 00:46 static/image/common/back.gif
remote sensing for a better job.
isn't the remote sense better connected to the load side?
if it is connected to the output jacks, I doubt the effectiveness.
johnme 發表於 2014-4-5 01:05 static/image/common/back.gif
what value do you have?
103~ 334, ..... Likely.....
johnme 發表於 2014-4-5 01:12 static/image/common/back.gif
isn't the remote sense better connected to the load side?
if it is connected to the output jacks, ...
That depends on the length of DCoutput cables..
billymud 發表於 2014-4-5 01:59 static/image/common/back.gif
103~ 334, ..... Likely.....
Perfect!!!{:1_326:}
billymud 發表於 2014-4-5 02:01 static/image/common/back.gif
That depends on the length of DCoutput cables..
Agree.
Usually, I make DC cable about 8 inches for external PSU.
Besides remote sensing, do you have any idea of choosing output capacitors ( both values and types)
making the transient response better?
johnme 發表於 2014-4-5 09:55 static/image/common/back.gif
Agree.
Usually, I make DC cable about 8 inches for external PSU.
i used to acquire Panasonic & Nichicon caps from RS-components Ltd.
Sometimes, I've Electrolytic and Tantalum caps populated in mix.{:1_262:}
johnme 發表於 2014-4-3 21:34 static/image/common/back.gif
手痕做多個sigma11 modified版,
用tmc compensation,
但係可以還原做原本sigma11,
C Hing, please confirm your adjustment pin cap typical value around Cadj=22uF, too big value would not help for output ripple or may cause side effect.
本帖最後由 johnme 於 2014-4-7 18:46 編輯
royccw 發表於 2014-4-7 17:48 static/image/common/back.gif
C Hing, please confirm your adjustment pin cap typical value around Cadj=22uF, too big value would ...
Thank you for the reminder.
The choice of capacitor size depends on what frequency you are working at.
The LT1084-NAS PCB provides the user the choice of using an electrolyte cap C7 and/or a film cap C8.
The 5mm pitch of C7 enable the user using as large as 220u, although I think (not tested)
that 100u is more than enough.
In my prototype, I only use C8 = 0.47u without using C7, it sounds good to me.
Have a look at the attached figure,
you may realize why I provide the option of using C7 and/or C8.
The LT108x family's rippple rejection at both ends of the frequency spectrum are relatively weak.
i.e. work best around 60Hz to 1kHz.
Also, note that in the figure, Cadj is 220uF, depending on what frequency range you are aiming at.
In the datasheet, it suggests 0.22u, if you aiming at optimizing ripple rejection around 10kHz.
Hope these information help.
