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Gate Driver ICs Forum Discussions

User17346
Level 2
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Level 2
Could someone clarify the situation with the gate driver allowable outputs?

I see in the datasheet:
Peak output current turn on (single pulse) IOpk+ 2.3A – RL = 0 Ω, tp <10 µs.

I also see:
Power dissipation (to package) PD 0.9 W

I also see:
Mean output current for load capacity discharging in range from 7.5V (50%) to 4.5V (30%) 1.65A -2.5A – CL = 61 nF

I am running at 25kHz (could be 15kHz up to 40kHz, but 25kHz is most likely), 24nF total capacitance, and 1.1ohm total gate resistance (2xIPT015 FETs paralelled,each with a 2.2ohm resistor) plus the FETs claim another 1.4ohm each; total 1.8ohm seen by the 2EDL23.

My assessment was thus that at the gate threshold voltage, I get ~4V/1.8ohm pull down = 2.2amp - similar to the max rating, and about what I need for the switching speed I want.
For pullup, I get ~12V-4V/1.8 = 4.4A. Again, for my application this is fine - but this is the source of my concern; the current is above the 2.3A specified.

The total power dissipated in the package and gate resistors is <25000Hz*25nF*12^2 = 0.09W, x2 channels = 0.18W - well below the 0.9 in the max ratings.
There will also be some in the bootstrap diode, but presumably much smaller, since the current is similar, but the voltage drop between the supply rail and bootstrap cap is much lower.

When I designed this, my assessment was that this was fine, since it was rated with the Rl=0ohm and 61nF, which I am well within, but I have had a small niggle all along that the drivers might not like the high current. I need high reliability.

I have used these FETs with a 4.7ohm resistor in a previous device driven by an NCP5183. They worked OK, but the switching was a bit on the slow side - 50ns or so rise time, but the gates charged/discharged over a much longer period - about 500ns. (I have an ultra low inductance layout; there is no ringing atall on previous versions, and the gate traces are routed within the source place of the respective FETs. Not too concerned about this... subject to testing)

My assessment of the datasheet was that the 2EDL23 was fine with this, that the ratings were given meaning that internal resistance of the driver would limit the current to 2.3A at 0ohm Rl, i.e.it has ~3 ohm internal resistance, and roughly 3/5 of the power dissipation goes into the 2EDL23; 0.12W, plenty of headroom.
In this case, the total resistance seen by the system is ~5 ohm, which is comparable or a bit faster than my previous design - perfect. I get similar or better switching than before, and I get a nice hardware overcurrent feature.

Can you verify this is the case? Seems perfect if so...

Many thanks.
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Srivatsa
Moderator
Moderator 5 sign-ins 50 replies posted 25 solutions authored
Moderator
For the datasheet rating, the internal Ron / Roff of the 2EDL23 is around 7 Ω and 5 Ω. This needs to be added to the external resistance of 1.8 Ω to arrive at the drive current in the given application of around 2 A which is below the peak current limit of the 2EDL23

For the power dissipation, static losses should also be included. Pls look at page 18 of the application note to arrive at the power dissipation nos.

https://www.infineon.com/dgdl/Infineon-2EDL_family_Technical_description-ApplicationNotes-v02_00-EN....

Pls note that the 0.9 W power dissipation limit is at 25 ° C.

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Srivatsa
Moderator
Moderator 5 sign-ins 50 replies posted 25 solutions authored
Moderator
For the datasheet rating, the internal Ron / Roff of the 2EDL23 is around 7 Ω and 5 Ω. This needs to be added to the external resistance of 1.8 Ω to arrive at the drive current in the given application of around 2 A which is below the peak current limit of the 2EDL23

For the power dissipation, static losses should also be included. Pls look at page 18 of the application note to arrive at the power dissipation nos.

https://www.infineon.com/dgdl/Infineon-2EDL_family_Technical_description-ApplicationNotes-v02_00-EN....

Pls note that the 0.9 W power dissipation limit is at 25 ° C.
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User17346
Level 2
10 replies posted 5 replies posted 5 questions asked
Level 2
Thanks for the reply. Good to know.

I don't think this rating is actually in the datasheet! I read it many times carefully, and again after you said, but I don't think it is there. I read a number of appnotes, but the one you linked is not attached to that part...

I have since received the boards and built them up. The worked near perfect first go.

The current I have measured by looking at the differential across the gate resistor, and the peak current is about 1.8V on each 2.2R resistor, which implies a current of 0.81A in each, 2 in parallel gives 1.6A on charge. The discharge is pretty much the same.
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The switching is very nice; textbook. Quite pleased with this so far - will have to see about reliability and I'll have to test the over current detection feature later... Bit hesitant about that one (don't like dead boards), but it needs doing.
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