Re: some question about using LT1316 as a flyback dcdc
- From: "Paul E. Schoen" <pstech@xxxxxxxxx>
- Date: Tue, 24 Mar 2009 17:20:48 -0400
"mayichao" <ustcmayichao@xxxxxxxxx> wrote in message
news:68b33200-87d5-45fd-9067-d353c1283011@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Mar 20, 7:20 am, "Paul E. Schoen" <pst...@xxxxxxxxx> wrote:
I tried your circuit and made a few changes to make it work. It may not
be
ideal. I used a MOSFET from the LTspice library and I made the
transformer
with lower inductance. The 2N3904 seems to be a low power zener. I added
another in series to boost the power supply voltage and thus give a
better
gate drive to the MOSFET. After 60 mSec the output had just about reached
5
VDC but it had not yet started regulating. I did not check the efficiency
and you really need to wait until it reaches a steady state to do so.
Probably 100 mSec, but it is a slow simulation as it is.
Good luck.
Thank you paul.
But i have another question that is:The mosfet's M2 action.
I think the mosfet make the voltage of Sw low than 30V(Sw -0.3 - 30).
And te datasheet said the efficiency of this circuit is 75%(udner
input 25V to 50V).
So the question is that if the input voltage is more than 40V the
efficiency must be lower than 75%.
why?
=========================================================================
I don't know why the efficiency should be lower at a higher voltage.
Usually the duty cycle is lower and losses from RdsOn are less significant,
so I would expect the reverse to be true. But I found that the circuit as
shown in the datasheet regulates at about 6.5 VDC, and the rough efficiency
calculation I did looked more like 50%, which is very poor. Even 75% is not
impressive. I think there are some problems with the circuit as drawn, and
perhaps you should try the flyback circuit in the LTC folder as a starting
point.
Also, I tried setting initial conditions and had problems with some values
for the output voltage, but it did work when I used lower values and the
simulation was faster.
Paul
.
- References:
- some question about using LT1316 as a flyback dcdc
- From: mayichao
- Re: some question about using LT1316 as a flyback dcdc
- From: Brett Holden
- Re: some question about using LT1316 as a flyback dcdc
- From: Paul E. Schoen
- Re: some question about using LT1316 as a flyback dcdc
- From: mayichao
- some question about using LT1316 as a flyback dcdc
- Prev by Date: Re: DOS Problem
- Next by Date: Re: Ear Infection from In-ear type Headphones?
- Previous by thread: Re: some question about using LT1316 as a flyback dcdc
- Next by thread: Electronic goods.......good for ever
- Index(es):
Relevant Pages
|
