Hi
I recently designed a PSU which includes a number of DC-DC converters based on LM27402/3. I initially designed them with Webench, and subsequently tweaked them using transient simulations in TINA, all of which looked OK. I could see no difference in the simulation behaviour of the circuits whether they used the 402 or 403 spice models.
Now I need to make a board, so I face the agony of choice.
My understanding is that the only difference is that whilst both devices provide current limiting by using the DC resistance of the inductor, but the 403 also provides over-temperature protection via a PN junction placed next to the inductor. The 402 is smaller, and for some reason the 403 is cheaper.
I'm not sure that I really need either current or temperature protection in this application, but would have no objection to having them 'for free' - except that some threads on here seem to suggest that these protections may be the source of some unreliability.
So I was hoping that a well-informed person (maybe from TI) could help me choose between the parts by commenting on these questions:
Is there any reason other than temperature protection to choose between the devices?
If I have reliability issues, can the temperature protection and the current-limit features be disabled, perhaps by non-fitting of the respective feedbacks or by some other means?
Thanks for your help,
Ian
