Reverse polarity protectet 5V to 3.3 regulator

[jstrebel]

Hi, I am looking for a 5V to 3.3 regulator ( I > 15ma ) for a sensor. The Board should be as small as possible. Therefore I try to avoid a schottky diode to protect the regulator against reverse polarity. No data sheet I found so far addresses this point.
Thank you helping me Jakob

 

[FvM]

I'm quite sure that schottky diode is the smallest solution that can be found. Diode for 15 mA can be really small.

 

[barry]

HOW MUCH greater than 15mA? 1000 Amps? But as FVM said, a diode can be pretty small.

 

[FvM]

Many manufacturers have regulators with reverse input protection, check e.g. LM2936.

 

[jstrebel]

Sorry I < 15ma

 

[KlausST]

LT1121-3.3

Klaus

 

[D.A.(Tony)Stewart]

Any Si series diode should work.

1.2 x 0.8 mm SOD523 plastic, surface-mounted package but more expensive

Common part

1N4148 Si 100 mA SOT123

 

[danadakk]

Many manufacturers have regulators with reverse input protection, check e.g. LM2936.

Spec wise its a transient rating, 1 mS nominal, 40 mS for absolute max rating.
Nada in datasheet on what happens much longer times....

Diode still looking real good for user protection hooking up reverse polarity.


Regards, Dana.

 

[dick_freebird]

As long as V5V(min)-Vf(-55C, 15mA)-Vdropout(15mA) > 3.3V
diode is good. But 4.5-0.8-0.2 is getting kinda edgy.

 

[danadakk]

Of course we could consider "ideal" diodes :

https://www.ti.com/lit/an/slvae57b/slvae57b.pdf?ts=1697717025936&ref_url=https%253A%252F%252Fwww.google.com%252F

https://www.diodes.com/assets/Datasheets/AP74700Q.pdf

Regards, Dana.