Help with building your Speeduino, installing it, getting it to run etc.
#23758
Hi everyone
I have a question, I can not find in my country the stp75ns04z?
I could use IRF1404, or STP60NF06 or STP16NF06?
I know that need the protect part, but I could not find the stp75 or stp62.
All of thst would work? IRF is very expensive, and stp60nf cost 1/4 of IRF. Will work the same as stp75?
Thanks
#23766
Um, sort-of. While the STP62/75NS04Z have built-in protections, they are still 10V gate drive to reach Rds(min), with no spec for operation at Speeduino drive voltage of ~4.5V to 5V. The problem is similar with the 3 choices you listed. If using a "standard" power MOSFET replacement, it would be preferable to use a logic-level part as described in this thread.

David
#23767
Thanks for replay me.
Perfect. I thinks this will work, IRLB4132, am I in the right?

>>Drive Voltage (Max Rds On, Min Rds On) 4.5V, 10V <<

Infineon Technologies

FET Type N-Channel
Technology MOSFET (Metal Oxide)
Drain to Source Voltage (Vdss) 30V
Current - Continuous Drain (Id) @ 25°C 78A (Tc)
Vgs(th) (Max) @ Id 2.35V @ 100µA
Gate Charge (Qg) (Max) @ Vgs 54nC @ 4.5V
Input Capacitance (Ciss) (Max) @ Vds 5110pF @ 15V
Vgs (Max) ±20V
FET Feature -
Power Dissipation (Max) 140W (Tc)
Rds On (Max) @ Id, Vgs 3.5 mOhm @ 40A, 10V
Operating Temperature -55°C ~ 175°C (TJ)
Mounting Type Through Hole
Supplier Device Package TO-220AB
Package / Case TO-220-3
#23774
MaaTrrIxx wrote:
Fri Jan 19, 2018 2:38 am
I thinks this will work, IRLB4132, am I in the right?
MaaTrrIxx wrote:
Fri Jan 19, 2018 3:32 pm
David I have a question the IRLB4132 will it work?, and if I put a diode betwen the injector and the output of the mosfet, it will protect the transistor?
The spec's on the two FETs you listed are generally OK, except the VDS (max voltage drain-to-source) is quite low. A new problem, that the device the FET is operating is often an injector, solenoid, etc, which are inductors, and they produce voltage spikes called flyback. Your idea of using a diode is good, except that stopping the spike at the device would be a better approach, in order to protect the FET. So, rather than a diode in the wire between the device and the FET, place the power diode reversed across the device's power pins, as in the link above. A common part for this purpose in EFI is the 1N4004. This shunts the voltage spike and feeds it back into the device (shorts the spike), protecting the FET, and also reduces heat by not using the FET's built-in diode as much. :) But . . .

Adding a shunt diode can slow the operation of the device as it feeds power back through itself due to the diode. :( The most common solution is to use a Zener power diode, which only shunts the voltage above the Zener rating. A Zener rating for a 30V FET might be around 25V and at least 1W. This allows the diode to only shunt the dangerous voltage levels above the Zener rating, speeding device operation. :) Given the added cost and complication of the Zener power diode solution, the alternatives are to use a 'protected' FET and live with more heat, or use a standard diode and deal with the slower device operation. These are your decisions. I hope that makes sense, and that it helps.

David

PS: Another solution is to use a gate driver, which drives the FET gate and protects Speeduino, such as the TC4424 used for Speeduino's ignition output. However, this is not included in the solutions above as it is even more expensive, but primarily because it is more complicated and difficult to hack into an existing circuit.
#23778
Thanks, if I use the IRLB4132, and adapt a zener (25v 1W) I have to put in parallel to the output of injector, that's right?
And in the schematic, on the ignition part have a 2.4k ohm resistor. And on the bom have 2.49k ohm. Which I have to buy? Could I put 2.4k?
#23779
MaaTrrIxx wrote:Thanks, if I use the IRLB4132, and adapt a zener (25v 1W) I have to put in parallel to the output of injector, that's right?

Sorry I don't have incite into this. :(
MaaTrrIxx wrote:And in the schematic, on the ignition part have a 2.4k ohm resistor. And on the bom have 2.49k ohm. Which I have to buy? Could I put 2.4k?
This is just for the LEDs so the value is not critical except that with the ignition LEDs the resistor also creates a voltage divider and if the value is too low the igniter might not receive enough voltage to operate properly on top of overloading the LED and cooking it. Values as low as 680 ohms were once recommended. A value higher then 3k would probably make the LEDs difficult to see when the system is set to 5 volts. I usually use a 2k ohm.
#23780
MaaTrrIxx wrote:
Sat Jan 20, 2018 3:26 am
Thanks, if I use the IRLB4132, and adapt a zener (25v 1W) I have to put in parallel to the output of injector, that's right?
Correct, and generally as close to the device as possible. One method is to crimp the diode into the connector terminal of the device, as in the image below, or simply solder to existing terminals and add shrink tubing if appropriate. The diode is acting as a form of flyback snubber.

David

I have used this method on valve solenoids mostly, such as idle valves, boost control valves, etc.; but are useful on anything that generates flyback greater than the driving transistor can tolerate, or to reduce transistor heat:
Shunt Diode - halfspec-norotors.png
Shunt Diode - halfspec-norotors.png (259.39 KiB) Viewed 964 times
(cropped image by halfspec, norotors.com)
#23784
You should use a FET with a minimum of 45V Vds otherwise you will get a slower turn off time and it will turn on during load dump. If the FET has an adequate avalanche rating then you don't need any other protection, using diodes will cause a slow turn off , OK for idle solenoids and similar but avoid using them on injector drivers.
proyect ford zetec-e 2.0 16v

Wow! Awesome. Thank you

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