SN6501: Simulation file fix

Hi Dennis,

We have a simulation file that includes the SN6501 + transformer system and the details can be found on this thread.

Thanks. 

Hello Shinu

The link you provide only shows a model of a transformer.  It does not include the SN6501 SMPS IC at all.  From the file you linked to it just has the following netlist:

.SUBCKT CENTX2W 1 2 3 4 10 11 12 13 PARAMS: Leak=500n RDCP=100m
+ Lpri=33u NSP1=1 NSP2=0.55 RDCS1=75m RDCS2=100m
R1 1 100 {RDCP}
L1 100 200 {Lpri}
L2 200 2 {Leak}
R2 100 2 1G
E11 5 12 100 2 {NSP1/2}
E12 12 17 100 2 {NSP1/2}
F11 100 2 VM11 {NSP1}
L3 3 17 {Lpri*NSP1*NSP1}
R4 17 4 {RDCS1}
RS11 6 3 1u
VM11 5 6
E22 20 13 100 2 {NSP2/2}
E23 13 18 100 2 {NSP2/2}
F22 100 2 VM22 {NSP2}
L4 10 18 {Lpri*NSP2*NSP2}
R5 18 11 {RDCS2}
RS22 21 10 1u
VM22 20 21
.ENDS
*$

Is there a file available that combines the SN6501 with a transformer?  The one I uploaded has a version but it does not quite work. I will also say that the above netlist is not the most intuitive for modeling a transformer. 

Hi Shinu

Maybe I should just ask you my end goal here.  For the SN6501, do you have any suggestions for a transformer to use to get a 2.5V output using a 3.3V input? Seems to me I need a step down transformer now to go to a lower voltage.  

I know this is a different topic than what I initially asked about but this is what I was trying to determine via simulation.  The datasheet for the SN6501, while it does provide formulas for calculating a required transformer value (or turns ratio) it does so using mainly 5V and 3.3V scenarios.  There is also an assumption that one has a LDO regulator following, which we do not.  

Hi Dennis,

Thanks for clarifying the query.

In most of the use cases, common rails are 3.3V/5V that is the reason the recommended transformers and reference designs are mostly for 3.3V and 5V.  One possible option to generate 2.5V is to use a recommended 3.3V to 5V transformer and configure the output in center tapped full bridge configuration. 

Thanks.  

Hi Shinu,

The datasheet of this part does state that it can be used for any output voltage, provided you have a transformer for it:

We do have Vcc at 3.3V so we are following the datasheet recommendations.

Is there a chance that somebody can take a look at my simulation file above and is there a fix for it so that it works to generate a DC output voltage?

dennis

Hi Dennis,

Yes, the device can operate at 3.3V and we have recommended transformers in datasheet for 3.3V operation. For 2.5V output transformer you can reach out to any transformer vendor (Wurth, Coilcraft ....etc...) and check.

Thanks.