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The IX4426 is MOSFET driver rated for "low-side gate drivers", but upon inspecting its schematics it is a push-pull circuit:

enter image description here

I should be able to drive a highside PMOS on its output. If the problem is the input voltage is not enough to turn on the PMOS of the push pull, can it be solved by adding a voltage shifter on the inputs?

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  • \$\begingroup\$ Note that the schematic diagram in the datasheet is a simplified diagram, and does not include everything in the chip. eg. What's inside those Schmitt triggers? So you can't just treat it like a couple of mosfets. \$\endgroup\$
    – Aaron
    Aug 3, 2021 at 19:55
  • \$\begingroup\$ Is Vcc for the IX4426 the same supply as your PMOS source voltage? \$\endgroup\$ Aug 3, 2021 at 22:22
  • \$\begingroup\$ We call this an XY problem , because you are asking the wrong question from an incorrect assumption from undefined requirements. \$\endgroup\$ Aug 4, 2021 at 9:27
  • \$\begingroup\$ @user_1818839 Yes, and the gate voltage of the PMOS can tolerate the full Vcc voltage \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 11:06
  • \$\begingroup\$ @DrakeJest Good, on both of those. When you post a question with such sketchy information. we have to check which bases you've covered. \$\endgroup\$ Aug 4, 2021 at 12:59

4 Answers 4

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If the problem is the input voltage is not enough to turn on the PMOS of the push pull, can it be solved by adding a voltage shifter on the inputs?

There's no need: -

enter image description here

In other words, for a supply range of 4.5 volts to 18 volts, the input level for logic 1 is greater than 2.4 volts and the input level for logic 0 is less than 0.8 volts i.e. it is roughly TTL compatible and can be driven by TTL, 3.3 volt CMOS logic or 5 volt CMOS logic outputs.

so i should be able to drive a highside PMOS on its output

Yes.

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  • \$\begingroup\$ Thank you very much, I want to use this on a 24v LED strip too (thus i have a board for 5,12,24 volt strips) do you think it would drastically change that much at 24v ? \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 11:19
  • \$\begingroup\$ This answer fails to recognise the overload -1 and only looks at the XY question on voltage \$\endgroup\$ Aug 4, 2021 at 11:43
  • \$\begingroup\$ @DrakeJest the bottom right hand graph on page 8 "appears" to indicate it'll be OK at 24 volts but, to be sure, I'd want to find a device that properly tabulates the data for up to 24 volts. And, the trouble you have now is that there aren't many MOSFET drivers expected to exceed 20 volts due to limitations on the maximum gate-source voltage for MOSFETs. And you need to check this for your PMOS device. \$\endgroup\$
    – Andy aka
    Aug 4, 2021 at 11:59
  • \$\begingroup\$ I guess i just have to design 2 pcb boards, and have both parts. with this IC and the old push-pull design i had. and just have to test both circuit. \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 14:20
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If the VCC of your application is higher than the IX4426, it won't work (as you'll exceed the absolute max rating of the IX4426) do something like this:

schematic

simulate this circuit – Schematic created using CircuitLab

Use an n-mos fet to switch the PMOS, the 2N7002 is a good logic level n-ch FET. If the n-ch FET isn't 'on' the pull up on the gate of the p-ch fet will pull the voltage to equal VCC and switch the p-ch FET off. When the n-ch FET is on, it pulls the gate of the p-ch FET to near zero volts and switches it on.

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    \$\begingroup\$ If the Vcc is high, as you are suggesting (that part in the OP works up to 35V), then I would add an R on the drain of M2, to prevent exceeding Vgs of M1. \$\endgroup\$
    – Aaron
    Aug 3, 2021 at 18:23
  • \$\begingroup\$ My problem with this ,when i simulated it in LTspice is fall time is 10x longer compared to having a push-pull circuit, i actually have a circuit that uses discrete components and would like to use an actual driver ([on this thread](thread(electronics.stackexchange.com/questions/579792/…)) , I have a high current load so that long fall time might cause excessive heat being dissipated \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 10:44
  • \$\begingroup\$ @Drakejest if you choose a pmos with low rdson you should be able to avoid heating. It all depends on the current you need to drive, I've been able to design circuits that can switch 10A with PWM with a similar circuit \$\endgroup\$
    – Voltage Spike
    Aug 4, 2021 at 11:11
  • \$\begingroup\$ I already am using the smallest i could find available DMP3013SFV and my target current is 8A. I will be placing the largest heatsink i could fit and hope that it will be enough. Of course after actually making this circuit, i might revert back to a circuit like that if i see that im just overreacting, \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 11:24
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@Voltage Spike's answer is good, unless Vcc is above the maximum gate voltage of the MOSFET (usually around 20V.) Beyond this, other methods are required.

If you have Vcc = 48V lets say, then you're going to need 48V to turn off the PMOS, and about 15V below this (48-15=33V, regulated), to turn the PMOS gate fully on.

That 15V difference (48V and 33V) can be the Vdd and Vss of the IX4426 and it should work well. But now you have another problem: how to input a correct logic signal to the IX4426? You cannot send it 0V/3.3V/5V as from it's perspective, 0V will look like -33V.

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  • \$\begingroup\$ Gate voltage is fully capable of the full Vcc voltage (Vgsmax = 25v) on my PMOS, The schematic on the question here is my current circuit and would like to fully replace the push-pull stage with a single ic \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 11:09
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Can I use this low side rated MOSFET driver to drive a high-side PMOS?

Yes, but why do you need to?
Are you planing to control direction with high side in a full bridge? (OK)
or deadtime in a half-bridge (NOT OK as skew is undefined)

driver rated for "low-side gate drivers", but upon inspecting its schematics it is a push-pull circuit:

Yes here "low-side" tells you the application purpose, not the internal characteristic. So again this begs the above question, why would you want it for a half or full bridge unless just using it for the low side ONLY . Using it for the High side implies you may have overlooking something else in your design.

Yet on their own merits with 3 variations of dual outputs, (A,B) (A!,B), (A,B!) these dual low side drivers have many uses and could be used for many things.

They accept any logic from 2V to Vdd for a "1" and <8 Ohms push-pull out.

Yet because of Schmitt Inputs, these are great for Noise immunity low side but terrible for hi+lo side drivers due to crossover-shootthru in a PWM Half bridge driver. You have no specs for rise-fall time matching or control over timing skew.necessary for complementary drivers.

So yes you can but WHY?

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  • \$\begingroup\$ I need to switch high side since i need to cut off power to smart led strips, if i use an NMOS the driver cost 2x as this one. And also need PWM switching since i would be at the same time controlling "dumb" strips \$\endgroup\$
    – DrakeJest
    Aug 4, 2021 at 11:31
  • \$\begingroup\$ What is the load current?. these are not designed for stripled type loads >1A x 8 ohms = 8 V drop \$\endgroup\$ Aug 4, 2021 at 11:42

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