Looking for some help selecting a zener diode for a reverse polarity protection circuit. I've never used this circuit before (usually a schottky diode) but now I am pushing up to 2A and a schottky diode would have to dissipate too much heat.
I need to protect a 5V LDO from reverse voltage, the regulator has a max input voltage of 18V, the P-Channel MOSFET Q1 (AO3401A http://www.aosmd.com/pdfs/datasheet/AO3401A.pdf) has a Vds of -30V which makes it perfect for my design but it has a +- 12V Vds so I guess I need a zener diode / resistor as I have drawn below.
Is the zener I have selected appropriate, MMSZ9V1T1G - https://datasheet.lcsc.com/lcsc/1809111622_ON-Semiconductor-MMSZ9V1T1G_C132795.pdf. The MOSFET has a 12V Vds so this diode should clamp this to 9.1V - yes?
Zener (Nom) (Vz): 9.1V
Max power: 500mW
The selection of the 100k resistor is just what I have seen used from searching other forums. I assume I need near zero current flowing here and just need the negative voltage to trigger the MOSFET.
How do I best select a zener diode and resistor for this circuit?
I need to protect a 5V LDO from reverse voltage, the regulator has a max input voltage of 18V, the P-Channel MOSFET Q1 (AO3401A http://www.aosmd.com/pdfs/datasheet/AO3401A.pdf) has a Vds of -30V which makes it perfect for my design but it has a +- 12V Vds so I guess I need a zener diode / resistor as I have drawn below.
Is the zener I have selected appropriate, MMSZ9V1T1G - https://datasheet.lcsc.com/lcsc/1809111622_ON-Semiconductor-MMSZ9V1T1G_C132795.pdf. The MOSFET has a 12V Vds so this diode should clamp this to 9.1V - yes?
Zener (Nom) (Vz): 9.1V
Max power: 500mW
The selection of the 100k resistor is just what I have seen used from searching other forums. I assume I need near zero current flowing here and just need the negative voltage to trigger the MOSFET.
How do I best select a zener diode and resistor for this circuit?
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