Mosfet IRFP460 driver TC427 fast switching issue

[wizardgrt]

Greetings to you all!

I've been away from field of electronics for a while Now, for a man like me, some things are quite muddy Here is a problem - I want to make some sort of flyback converter (closely said). I'm wobbling about Mosfet IRFP460 variable switching speed (1 - 20kHz). Is the gate driver TC427 capable for direct coupling with upper mentioned MOSFET, to satisfy demanded conditions, or it needs to be couppled with additional components in configuration, as described within the examples attached below? :shock:

Thanks in advance!

Best regards!

 

[alexan_e]

TC427 (or TC4427 which is improved version) will work fine assuming that you are making a low voltage circuit and you are using the Nmosfet as a low side switch.
If your intension is to build a high voltage circuit take a look at IR2110/2113 , maybe it is closer to what you are looking for.
If you give a rough schematic of the circuit you intend to build I could give you a better answer.

Alex

 

[RCinFLA]

You did not define how fast you need the switching time.

The IRFP460 has 210 nC of total gate charge. If you want 200 nsec of turn off time you need a peak drive current of 210 nC / 200 nsec or 1.05 amps.

The TC427 should have enough drive. Its output equivalent resistance is about 10 ohms so a 12v to 15v supply should provide the required current.

Keep in mind the potential circuit parasitic resistance and inductance in the source path. Sometimes a series resistance in the gate path is used to reduce the ringing causes by the source inductance but it cannot be too large in resistance or switching time will suffer.

The driver IC output Vss pin should have its own runner directly to MOSFET source. A second high current runner is taken off the MOSFET source for its high current output path. This avoids ground loops where the MOSFET high current source path resistance from eating up gate drive voltage.

 

[wizardgrt]

Thanks guys! Answers were truly helpful!

I have another situation - isolating power electronic circuit from control electronic (PIC18F). I have 4 optocouplers 6N136, 6N137, 6N138, and 6N139 as choise. Little confusing fact that I'm not completely informed about is output type - TTL/TTL, TTL/CMOS,... TC427 input is TTL/CMOS compatible, and i'm littlebit unshure about connecting TTL/TTL optocoupler output with TTL/CMOS TC427 input. Is that kind of connection correct? Or it has to be TTL/CMOS compatible output connected with TTL/CMOS compatible input? :-?

Thanks in advance!

 

[alexan_e]

The datasheet of TC427 says

with 4.5V ≤ VDD ≤ 18V,
VIH Logic 1, High Input Voltage min 2.4v
VIL Logic 0, Low Input Voltage max 0.8v

I don't see the problem, these can work fine with the optocoupler output

Alex