Need help driving two IPS1031 Low-Side MOSFETs from a PIC

The IPS1031 is a Low-Side MOSFET Driver that drives its own MOSFET. I am planning on incorporating it into my design, but most of its spec sheet is total gibberish to me.
I am driving two of them off of a single PIC output which can sink 3.7-5V @ 25mA.
The IPS1031 datasheet: https://www.electro-tech-online.com/custompdfs/2006/08/ips1031.pdf

Attached is a schem I used for its simulations purposes. Through the use of "OR" diodes, only two IPS1031s are on at any single time; Q2 is saturated when either Q1 or Q3 is saturated. S1 and S2 signafy two different PIC Outputs.

forgot to mention the question

LMAO, I forgot to mention what it was that I needed help on. I was concerned about the required voltage to turn on the mosfet, and if in combination with the diode and the pic output, if it would even see this voltage.

Why create a new thread?

https://www.electro-tech-online.com...-critique-this-double-or-relay-circuit.23235/

This is not a good idea since no one will read the other thread and as a result they might ask the same questions again an give you the advice again which is a waste if time.

If you take a look at page 4, you can calculate the approximate input resistance, and look at fig 5 on page 6, you can see the effect of the input voltage on the switch resistance.

Just read the graphs, they'll tell you more than any of us could...

BTW

Thanks, because I can only run on 25mA at around 3.8 volts, I have decided to use transistors instead of the FETs.

well, the input resistance is ~20K in fault, or 150K normally, which gives an input current of ~0.25mA or 0.03mA, so I don't see much of a problem...

the IPS1031 needs at least 4.5 volts at the gate to function, I would only be given it no more than 3.8. It would still work though?

The IPS1031 will work at lower values of Vin. Look at fig 5 on the datasheet. The Rds at 3.8V would be about 125% of the 5V Rds but still quite usable. Note: I find this to be an odd part as it doesn't use standard MOSFET terminology - Vin appears to be Vgs. Few disti's carry it (not mouser or digi). One word of warning - the diode drops may push Vin too low.

However, the IPS1031 seems like massive overkill to me. a simple logic level MOSFET like the IRL510A ($.80 or so) would work ok and be cheaper. I try to pick devices that are readily/widely available.

But even cheaper would be a small signal NPN like the 2N3904 (< $.10). If your load really is 5K (which I kind of doubt - that's only 2.4mA), then the NPN would be fine unless it needs exactly 5V. Heck, the PIC could source that current no problem.

why use a IPS1031/MOSFET/NPN to drive LED D2? the PIC can source/sink all the current you need.

R7 and R8 are too small. You will get something like 66 mA when you want more lik 20 mA. try 470 or 510 (standard values).

I'm not a fan of the LED across the relay coil (D1). It increases the work that the switch has to do. I'd use a seperate NPN to drive it but it's not necessary.

Finally, I'm not sure why you are using the structure you are. why not simply have one PIC pin enable the relay and one control the load. Your logic will be slightly different but you get rid of D3, D4 and R2 and simplify the circuit.

Thanks Philba, your response helped me in my decision. The PIC is pre-progged. I am most likely going to use a darlington transistor in replace of the IPS1031. BTW, how would you go about running the LED off of another transistor? And youre right the load isnt 2.4mA but is actually around 200mA

Here's a diagram that should help you. note that the led and r2 can be replaced with any resistive load and use Ic in place of If to calculate the base resistor.