Still, makes no sense to change perfectly arranged circuit with P FETs, but okay, Pfet to top side, gate to VCC via resistor and transistor pulling gate down via MCU. No special drivers needed . You can use IRLML6401 as PFET as long as the voltage remains below 12VI would like to replace the irz44 N channel with a P channel mosfet. I want the LED Cathode grounded (-) . i would like no extra IC to drive the mosfet,could add resistors or diodes.. This is a commercialy available circuit board.
The voltage on a automobile can go over 14volts. The led is going on taillights are the same bulbs are used as brake lights. The mosfet has to be + voltage out. The cathode is has to be grounded to the ground of the automobile. I would just like to replace the mosfet not add any other components except resistors or diodes. Trying to find a p channel mosfet to replace the n channel mosfet.Still, makes no sense to change perfectly arranged circuit with P FETs, but okay, Pfet to top side, gate to VCC via resistor and transistor pulling gate down via MCU. No special drivers needed . You can use IRLML6401 as PFET as long as the voltage remains below 12V
View attachment 245595
Changing mosfets just N to P will cause a lot of smoke, but good luckThe voltage on a automobile can go over 14volts. The led is going on taillights are the same bulbs are used as brake lights. The mosfet has to be + voltage out. The cathode is has to be grounded to the ground of the automobile. I would just like to replace the mosfet not add any other components except resistors or diodes. Trying to find a p channel mosfet to replace the n channel mosfet.
I have alreaChanging mosfets just N to P will cause a lot of smoke, but good luck
The circuit you drew won't work. When the GPIO is 5V, Vgs on the MOSFET will be -7V to -9V and that will turn on many MOSFETs. To insure that they turn off, you need a pull up resistor on the gate. That will cause a problem with forcing current in to the I/O. If you force enough current, the IC will latch-up. If latch-up occurs and you don't remove power quickly enough, it will be destroyed. I've used some devices that limited current forced in to the output to 100uA.chech schematic
I told you before. You CAN NOT replace N fets with P fets without other modifications. Really, just educate yourself, Internet is full of examples how to use P FETs in switching purposes. You cant just randomly throw components into circuit and expect them to work without knowing their operation principles.chech schematicView attachment 245608
Here's a circuit that will work. It requires you to change the polarity of the output in the PIC but I guess you already knew that.chech schematic
This is what I am looking for but I need a to-220 case. why this should not be used?Here's a circuit that will work. It requires you to change the polarity of the output in the PIC but I guess you already knew that.
I normally wouldn't recommend this hack, but those were the constraints you imposed. I've used this method as a quick and dirty method to level shift between 3.3V and 5V circuits and it usually becomes permanent because it works and takes less space than using proper level shifting.
View attachment 245651
The zener diode needs to be a voltage large enough to force the gate voltage high enough to turn the MOSFET off when the GPIO is HIGH, while allowing sufficient Vgs to turn it on hard enough when the GPIO is LOW.
When the GPIO is HIGH, R1 and the zener limit the current forced into the output. I didn't find anything in the datasheet that specified the maximum that this current can be, but it did say to not allow the voltage to forward bias the parasitic diode on the output to the rail. That current is what can cause latch-up.
From post #5, it would appear that this is for a motor vehicle.
You should be aware that external lighting is regulated in some countries (i.e. USA). If you're using DOT approved LEDs, they'll be designed to operate from 12V so R2,4,6,8 aren't needed. R3,5,7,9 also aren't needed. The PIC outputs should be able to drive the gate cap.
When I looked for P MOSFETs, I used the case style from the N device you mentioned.This is what I am looking for but I need a to-220 case.
If you're referring to using the diode for level shifting; purists might frown upon it. Diodes have long been used in integrated circuits for level shifting...why this should not be used?
If you have two nice stable, accurate power supplies, and an accurate zener diode, and don't require any great speed from it, it will work fine.why this should not be used?