High voltage switching power supply

[Winfield Hill]

colin wrote...

this is the tea1541 app note i was looking at earlier although it doesnt
give eht circuit its just to regulate the supply to the eht supply doh
!although its still pretty usefulll

http://www.semiconductors.philips.com/acrobat/applicationnotes/AN10205_1.pdf

I'll see your tea1541, and raise you a 30W 26kV resonant HV converter,
see Philip's AN00013. OK, the subject tea1601 with its 600V FET is
an unobtanium vapor-chip, but the app note does have some good stuff.
http://www.semiconductors.philips.com/acrobat/applicationnotes/AN00013_1.pdf


Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

 

[colin]

colin wrote... http://www.semiconductors.philips.com/acrobat/applicationnotes/AN10205_1.pdf

I'll see your tea1541, and raise you a 30W 26kV resonant HV converter,
see Philip's AN00013. OK, the subject tea1601 with its 600V FET is
an unobtanium vapor-chip, but the app note does have some good stuff.
http://www.semiconductors.philips.com/acrobat/applicationnotes/AN00013_1.pdf


Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

yes i just found that one too was gona post it but u beet me to it.

just dont stick you finger on the big red thing when its running !

its a shame that ic doesnt stay on resonace, rather it reduces its frequency
moving closer to the center frequency to increase output, it means you have
to precisly control the frequency limits, and you cant be sure to operate
exactly at resonance, becuase if you end up the otherside it wil try to
decrease freq inorder to increase output but instead the op will fall and
hence lock up. simlar controler ics do this such as the mc34067.

also note that it uses a diode split lopt, this not only reduces the effect
of intra winding capacitance but actualy makes use of it, they were all the
rage in TVs many years ago now. i think they need more turns becuase u cant
use a tripler with them, but were suposed to be much more reliable. the
secondary is split into layers and there are diodes inside the transformers
in series with them. so eliminating the capacitance between layers from
being reflected back to the primary.

Colin =^.^=

 

[Robert Baer]

*snip*

this is the tea1541 app note i was looking at earlier although it doesnt
give eht circuit its just to regulate the supply to the eht supply doh
!although its still pretty usefulll

http://www.semiconductors.philips.com/acrobat/applicationnotes/AN10205_1.pdf

this is the one i was realy meaning but its for a tv deflection ic
TDA4855/58, but u can ignore the deflection parts.

http://www-eu2.semiconductors.com/acrobat/applicationnotes/AN96052_1.pdf

i just looked for uc3842 and eht on google im sure theres more to be found
...

Colin =^.^=

Thanks!

 

[colin]

yes interwinding capacitance can be a killer, the capacitance on the
secondary goes up with the number of turns and when its reflected back to
the primary it increase by the square of the turns ratio. so its
proportional to turns ^3

one way to get round this is to use resonant technique, long time ago i made
a cdi gnition unit for a motorbike, this used same technique to keep the
eficiency high as posible before mosfets were available, it used a simple
cmos hex shmit inverter, and free ran as a relaxation oscilator untill the
output gets going into resonance then the colector voltage faling below a
few volts trigered the next cycle of turning the transistor on, thus the
transistor always turned on at zero voltage so no switching loss, a largish
capacitor could then be used acros the colector to eliminate turn off losses
too and aded to the resonance, but too high and you need a larger
inductor/transformer becuase some of the stored energy goes into charging up
the capcitance rather than into the output. it was quite simple just used 3
of the 6 hex inverters and a single transistor driver.

i keep looking for a smps pwm control ic that uses the same technique but
most just seem to ramp the frequency and hope it hits the resonant point.


Colin =^.^=

i just found what i was looking for ... tea1620/1/2/3

http://www.semiconductors.philips.com/acrobat/datasheets/TEA1620P_1.pdf

its a simple 8 pin pwm with integrated 650 volt 48ohm switch theres also
versions down to 6.5 ohm

it has valey point detection wich means it switches on the transistor only
at minimum switch voltage, thus if u have large capacitance it doesnt wreck
the output transistor with large switch on curents.

the application is rated for off line 80-260v suply but the ic wld work
directly from 10-40v easily.

Colin =^.^=