Switching a high frequency off/on with logic input

Other Hardware General Electronics
1

I need to have a pulse gen running consistently and send its output to the gate of a MOSFET, but the Arduino Logic "HIGH" Logic "LOW" needs to decide when it is going to the gate. I have made something on simulator for testing and illustrating the point, but I doubt it is gonna work in practice. So I need some hardware that can do it for me. I am not looking for those SSRs with opto in them as they cannot switch 20KHz. Here is a diagram of what I have in mind. Suppose the left side source (20KHz) is Arduino's output and the 80KHz is what it needs to switch on/off

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2

You can use logic chips such as a 74HC08 which will give you 4 2 input and's. You can parallel all of them and use the output to drive your load. Without voltages etc this is the best I can do.

3

Thanks. what are these chips called? I mean the category they belong to. I looked at the datasheet and it looks like the input is around 4v which is not enough for the gate. If I knew what they are called, could search for different chips that meet my needs. Thanks tho

4

OOPS I made a typo, I typed 73HC08 instead of 74HC08. They are basic logic chips available in a lot of places with many different manufacturers. Try your favorite chip supplier. They should be less then a buck.

5

Thanks, I noticed the typo, it is ok, but I search and search and the chips are not puttin out enough current (~32mA) Will it be able to drive a gate at 20KHZ?

6

I cannot give you a complete error free answer but probably yes. You can parallel the 4 gates which will give you well over 100mA drive. The next thing is to determine if the MOSFET is properly enhanced with a 5V Vgs signal. I grabed a stock drawing,hope it helps.

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You can lower the gate resistor R1 to maybe 20 Ohms and connect the gate(s) to Pin 5V. R2 should be placed on the processor port that controls this. That will keep it off during reset and initialization.

7

Unfortunately, my MOSFETs need 10v min. and with that fast switching, it can go up to 150mA (IRZ44N) The fact that it has 4 inputs is dream come true since I need it for 3 Half-Bridges (only Low-Side MOSFET needs PWM) but the voltage and current limitations of this 74HC08 is heartbreaking!!

8

There are some CMOS families that may work for you, it is the 4000 series (CD4081) and 74C series (74C08). Both will work at 15V. These are logic devices, not power drivers.

What are you trying to switch?

9

(IRZ44N MOSFET at 20KHz speed and varying PWM.

10

The IRLZ44N would work.