inductorswitch-mode-power-supplytransformer
While designing an LM2586 SMPS circuit using the TI Workbench, the software recommended the following transformer:
This is apparently the 749196510.
The TI workbench states that this is a 89.1uH part. However, the datasheet states that the inductance base is 9.9uH. Even if I were to connect all 3 primary windings in series, surely that would only result in 29.7uH? Is there a mistake somewhere?
For instance, i want to use the following transformer: http://nl.farnell.com/bi-technologies-tt-electronics/hm42-10001lftr/transformer-gate-drive-300uh/dp/2192063
You can't use the transformer you want to - it isn't rated for doing what you want.
Unfortunately i get stuck at the part where i have to choose the transformer (the bottom 3 choices from the "design" tab).
What's wrong with the design page that it produced: -
It tells you: -
It even gives you options for using different ferrite cores - see radio buttons.
What were you expecting? You want something easier? Yes, well go to premier magnetics and choose a design for 5V and 1A (such as this one) and they do the job for you using a Power Integrations part: -
They'll sell you the transformer and provide all the info for the other magnetics. If you are still insistent on using the NXP tool then start learning about transformers so you can take the premier magnetics transformer and feed the data back into the tool.
If you look at the datasheet, it says Resonant Converter. The only resonant converters that I have worked on were to get high voltage outputs without feedback. I think there may not be any difference in the transformer construction and you can use it for the much more common PWM scheme SMPS.
The 4A saturation current spec is for the primary.
The transformer can function for 400V or below. One of the key spec here is the primary inductance -- 400uH, it determines the current rise for a given on time. Back of the envelope calculations: at 120VDC input, 0.5us on time (50% of the period of 100KHz), discontinuous current mode (flyback topology), the transformer can transfer no more than 45W. At 320VDC input, 320W. And these are assuming 100% efficiency.
SMPS can be fun, but be careful when dealing with 120V or greater. In the common flyback topology, the flyback voltage would add on top of that.
Best Answer
Inductance goes as turns squared, so all three primary windings in series would get you 89.1uH.