Re: SPICE model for PVI1050N

From: Kevin Aylward (kevin.aylwardEXTRACT_at_anasoft.co.uk)
Date: 06/26/04 

Date: Sat, 26 Jun 2004 13:35:15 +0100

Christian HOSTELET wrote:
> "Kevin Aylward" <kevin.aylwardEXTRACT@anasoft.co.uk> écrivait
> news:lwXCc.38321$ly2.8431@doctor.cableinet.net:
>
> [snip]
>
>>
>> I have had a little play with this. I had a look at the graphs. They
>> show an output graph something like the output characteristis of a
>> transister, but Vce being replaced by the input current. This implies
>> some sort of limiting. However, into a s/c the current follows the
>> input with a scale factor, requiring limiting to be removed.
>>
>> What I have done here, is use an iout=i/(i+K) to form a limiter, but
>> multiplyed K by the output voltage such that as V goes to zero the
>> limiting goes away.
>>
>> The graphs are roughly of the right shape with different loads (1M to
>> 10M to open and under s/c conditions, but I have not tweaked them
>> yet.
>>
>> Preliminary idea PVI15080N:
>> *************
>> .subckt PVI anode cathode out_plus out_neg
>> *
>> *copyright kevin aylward, www.anasoft.co.uk.
>> *this model can be freely used provide this notice is included
>> d1 anode sense1 dmod1
>> vsense sense1 cathode 0
>> biout out_plus out_neg i = -0.001 * i(vsense)/(1 + 80 * i(vsense) *
>> v(out_plus, out_neg))
>> rout out_plus out_neg 5Meg
>> dout out_neg out_plus dmod2
>> .MODEL dmod1 d(rs=10 cjo=2p is=100p N=2.5 bv=7)
>> .MODEL dmod2 d(rs=10 cjo=2p is=100p N=1 bv=30)
>> .ends PVI
>> **********
>>
>> I have ignored the output string of diodes for now. I have only spent
>> a little while on it, so there may be a better way or more accurate
>> way. The "80" and "5Meg" need to be twiddled to get the best match.
>>

>>
>
> Looks great !
>
> I'll play with it, especially the B function.
> For Rout, it seems to be a linear function (or inverse of) of the
> input current i(Vsense). I'll look at that.

Well, I just used a fixed resistor. The basic vout verses Iin shapes are
ok as the load resister changes. Do a DC sweep of 0 to 20ma, then param
step the load from 2M to 10 meg. The equation wants a bit more of a
tweak to get a better fit though.

The turn off response really needs an additional term. The data ***
shows a turn off speed independent of load resister. Not sure why this
should occur. I havent looked at the physics of these things yet.

I tweeked the diodes a bit as as well

.MODEL dmod1 d(rs=10 cjo=10p tt=1n is=10u N=6 bv=7)

.MODEL dmod2 d(rs=10 cjo=10p is=1u N=1 bv=15)

To get a better match on typical leakage, but this data is guestimated
as well.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
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