IR2110 question (help me)

[albert_emule]

I was knowing that the IR2110 needs the drawing PCB specifically to work correctly.

they are in the link:

http://img155.imageshack.us/img155/8614/ir2110yx0.jpg

http://img155.imageshack.us/img155/1...tir2110dw0.jpg

http://img120.imageshack.us/img120/8...pir2110jf6.jpg


the prpblema, is that these are of double face.

I would like a PCB of a face, for the IR2110

does anybody have any suggestion?




Thank you very much.

Albert

[Eva]

You can't do fast switching with single sided PCB. Learn to make double sided PCB prototypes and how to use ground planes to improve the layout by reducing parasitic inductance.

[Bakmeel]

Other than that, it can do fine on a single sided PCB if your switching is not higher than 130kHz or so. Make sure you place the bootstrap supply close to the IC.

[Eva]

Fast or slow switching has absolutely nothing to do with frequency, it has to do with voltage rise and fall times and with current rising and falling slopes (di/dt).

The high parasitic inductances from single sided PCBs really put a limit on how fast currents may be allowed to rise and fall without developing voltages across these inductances high enough to damage components or disturb the circuit. Remember that V = L * di/dt.

IR2110 and similar drivers are easily damaged by too high parasitic voltage drops on PCB track inductances (on circuits that would otherwise look perfectly ok to anybody not understanding these phenomena).

[Bakmeel]

Though that may be absolutely true, I don't think that completely excludes the use of single sided PCB's or even breadboards. If you put sufficient resistance in series with the Mfet gate, such to absolutely respect the 2Apk current delivery, di/dt will not be so high from a few cm of wiring or PCB trace.

Having another look at the schematic posted on top, I notice there are no freewheeling diodes added or "turn-off bjt" at the Mfet gate. Especially adding a few clamping / freewheeling diodes will help protect the IR2110. This is common practice in our labs when building breadboards.

I usually burn my IR2110's because I fried the FET attached to it. I think this is more of an issue when it comes to device reliability.

[Eva]

The inductive voltage drops due to the currents being switched are the ones likely to damage IR drivers, particularly when body diodes are involved. Gate drive currents are not usually the problem.

[Bakmeel]

Do you mean pulling the source voltage of the upper fet below the 0V reference?

[Eva]

Pulling the lower source below 0V, pulling the lower gate below 0V, pulling the lower gate above driver supply voltage, pulling Vs below COM, and all this applied to the upper MOSFET. More complex interactions are possible depending on how PCB leakage inductances are distributed.

My current amplifier project switches up to 72A quite fast and complimentary ground planes are used (almost all of the remaining inductance comes from TO-220 legs!), and all resonances are damped, and these inductive spikes can still get as big as 10V-15V (10-20ns) during hard switching at maximum current and maximum heatsink temperature.

[Bakmeel]

If your amplifier is a professional product and you're having issues in leg inductance, perhaps you could try a different package like D2... TO220 and TO248 are indeed not optimum for fast & hard switching.... but that's another story.

All the effects you are referring to are consequence of the power cell layout in the PCB. The driver is affected by it, but it is not the cause. A bit of ground plane below the driver will not solve the spikes nor save your driver except perhaps the last few volts that make or break the case.

If you're not after cutting edge performance, like perhaps your amp, layout on the IR2110 is not critical. If you can resolve transients in another way, even breadboards will suffice....

[Eva]

Fortunately I don't have reliability problems, it's all within safe margins, but many people does...

btw: When I said complimentary planes I was talking about the power switching layout, 1nH or so as seen from the switching devices.