SiC MOSFET gate driver design and functionality

[mike buba]

Hi All,

I have a general (basic) question about the gate drivers. I am looking into using SiC MOSFETs for my project, and I understand I need to use gate drivers to convert the PWM signal (0-3Vdc) to the high-current drive input (e.g., 0-12Vdc).

I came across this gate driver, CRD-001 Wolfspeed (datasheet), with the schematics shown below. The price is >$50. Even if I calculate the BoM price and try to do it myself, the price comes in at over $30.

On the other hand, MAX22701E (datasheet) is approximately $5, including the additional recommended circuit:

Both are isolated gate drivers, where MAX22701E has (proprietary) integrated digital galvanic isolation, and the CRD-001 (a more expensive one) uses an opto-isolator component. MAX22701E uses the board's Vcc, while CRD-001 uses two DC/DC converters (each costing approximately $15).
There is also the TI TIDA-01605 (web and schematics), which has +15Vdc for high and -4Vdc for low, where "negative driving voltages allow for safer operation and improved noise immunity", while in the previous two, I think, low is 0Vdc.

Basically, the question is which one is 'better', i.e., how to define what is 'better'.
Also, if I am to design my own gate driver, should I be leaning more towards the CRD-001 or the MAX22701E design or something else?

Thanks, MB

 

[dick_freebird]

SiC MOSFETs may need negative drive for best leakage.
They are crappy like early '80s power MOSFETs used to be.
So you might like drivers from that vintage. A couple of my
old (long gone along with the fab) driver designs were that
way, 0-8V in and "- whatever" to "+ whatever" output swing.

UC37xx drivers, if you can still find them, look carefully at
whether "logic ground" and "power ground" are kept
independent or bonded inside the package / on die.

If you are for flying high side drive then you want those
isolated drivers. A low side switch can use a cheaper simpler
driver. But keep negative gate rail in mind, in evaluating /
selecting SiC MOSFETs as depending on leakage and
turn-off speed, you may need that.

 

[FvM]

There's no secondary power supply in the shown MAX22700 circuit. In so far it's no fair comparison.

 

[mike buba]

There's no secondary power supply in the shown MAX22700 circuit. In so far it's no fair comparison.

Pricewise, yes. Probably another $10 to $20 more if I go with e.g., DCR010505U.
But leaving the price aside for a moment... I am more interested in terms of functionality; which would be more advisable to use?

 

[Easy peasy]

you have not mentioned high side voltage, or frequency - but the IR2110 / 2113 accepts 3v3 inputs and can go to 600V ( nearly ) high side, as well as the low side drive - needs buffering for best results.

 

[FvM]

First step is identifying driver requirements:
- gate voltage
- gate current/charge
- isolation working voltage
- isolation dv/dt (particularly for SiC high side drivers)

Driver module CRD-001 is rather old and apparently designed for high gate currents. We usually don't have so many parallel gate resistors, except with highest power IGBT drivers.