The LT3045 datasheet clearly mentions reverse input protection, however I find nothing in the LT3094 datasheet.
Can a diode be inserted between the pins IN and PGFB of the LT3094 datasheet to provide such a protection, similarly to the LT3045 ?
I tried to simulate the situation in LTSpice, but get unrealistic currents flowing in the input pin (5 MA).
Thank you.
Thanks for the post. The LT3094 has numerous parasitic diodes referenced to IN and it violates the abs. max. rating to forward bias any of the parasitic diodes. Note 2 from the datasheet lists the parasitic diodes and I show Note 2 in the image below. In other words, D1 you show in the image above is backwards if you want to prevent the IN to PGFB parasitic diode from conducting. Also, how are you preventing the IN to OUT parasitic diode from conducting if IN gets pulled up to GND with COUT charged?
In actual practice, I tell customers that IN should always be the lowest voltage applied to the LT3094 (or similar LDOs like the LT3090 for that matter). Sometimes it is necessary to put a diode in series with the IN supply to fully protect the LT3094 if it is possible that IN will be pulled up to GND when COUT holds OUT negative. Don't put the series diode between the IN bypass capacitor and the LT3094.
