Hi to all :)
Does anyone have a circuit diagram for this driver? I am searching through web but nothing. My main question is what kind of input does it take to pin2?
Do you have something else to propose me for fast mosfet switching?
Thanks
http://ww1.microchip.com/downloads/en/devicedoc/22019a.pdf
Quote from: Jeg on September 30, 2013, 03:53:33 PM
Hi to all :)
Does anyone have a circuit diagram for this driver? I am searching through web but nothing. My main question is what kind of input does it take to pin2?
Do you have something else to propose me for fast mosfet switching?
Thanks
http://ww1.microchip.com/downloads/en/devicedoc/22019a.pdf (http://ww1.microchip.com/downloads/en/devicedoc/22019a.pdf)
Hej Jeg,
The link you included is in fact the data sheet of the MCP1406/07 MOSFET driver IC. As such, it answers most of your questions, just read it through.
SO it says pin 2 is the (high impedance) input (TTL/CMOS level compatible with hysteresis), except for the TO-220 case where pin 2 is the negative rail (ground).
DO not expect a detailed circuit diagram for such drivers, most manufacturers do not disclose them in detail, in most cases some active device circuit symbols are drawn with block diagram-like additions like in this case too.
Data sheet also includes what other driver ICs are compatible with these types.
Thanks gyulasun :)
I was trying to find something to guide me. I hadn't realized that it needs TTL pulses in the input.
Do you have something to propose me for input? I'd like to have frequency control up to 1 or 2 MHz and duty cycle range from 1 to 99% or close. I don't want microcontrollers, i'd like something simpler. If i will not find something i will use a 555 and a comparator.
I just show on 555 datasheet and it can't go in MHz range. Anyway i'll search more!
Well, I would recommend you the newer CMOS version of the old NE555, it is the LMC555 or TLC555 and these timers are able to run up to 2 MHz at least.
Here is a link to a schematic with LMC/TLC555 and with independently variable frequency and duty cycle controls:
http://www.overunity.com/8597/solid-state-orbo-system/msg234095/#msg234095
From another member too, but using another CMOS version of the 555, with at least 1 MHz upper frequency, also independent variable duty and frequency control:
http://www.overunity.com/8411/steorn-demo-live-stream-in-dublin-december-15th-10-am/msg243175/#msg243175
Data sheet for the LMC555:
http://www.ti.com/lit/ds/symlink/lmc555.pdf
The driver IC you asked with the data sheet accepts not only TTL but CMOS level inputs too, the above circuits can directly drive it.
Well, i remembered a PLL circuit that i had built a few years ago.
http://www.sm0vpo.com/use/synth-00.htm
If someone wants to use it, the only mistake on the diagram is at 4046 Voltage Controlled Oscillator (VCO). It needs pin 5 to be grounded. Works fine!
But, i think i 'll use the 555 solution. Simple enough and fits for my application. Thanks for the links
Hi to all :)
Does anyone know how to supply MCP1406 driver? It has an output capability of 1.3A continues current, and 6A pulsed current. I used a simple LM7818 but after some seconds driver was gone! LM7818 was very hot but it survived. MCP1406 not!!!
I attach my driver circuit to see if i made other mistakes. Input is a CMOS pulse train of 1.3MHz. Output goes straight to IRFP460 which switches a dc voltage of 400V.
Thanks
Jeg
I dunno. Try using one or the other of the outputs, not both to the same mosfet gate.
Hey Tinsel
Thanks for the reply
I "discovered" yesterday that MCP1406 has the same layout as TC4429. My connections on driver side seem to be right. The two outputs are linked together to make a push pull output that has active rise and fall times. That makes the mosfet to be quicker and able to achieve really short pulses.
What i did wrong in the first place, was the system test topology. I had gave 18V pulses for mosfet input (mc1406 output), while at the same time mosfet's Vdd was lower than that (12V from a battery) That is wrong because the mosfet's intrinsic diode starts to conduct and high amperage passes from Vdd to ground. So i burned the driver and finally my IRFP460 mosfet.
This was my first mistake.
Then i raised Vdd to higher voltage and that stopped the "destroy effect" ;D But still no output at mosfet's side.
I will test some different values of Rbias and Rgate, but i am not sure that it will make it.
My main purpose is to create pulses as short as 400-500 ns from a dc source. 400V Vdd, 18V dc pulses Vgate (400ns).
I have the dc source and i 'd like to switch it!
Is that realistic with the above values???
OK... can you show your complete circuit including the power supply voltages?
I'm using IRFP460 in my Class E SSTC and when it is working right it makes pretty fast pulses, it operates at around 4 MHz. But I'm not using a driver chip.
Which method you recommend to make it pulse at 4MHz? I used TLC555 and i reached around only 1,3MHz.!
In the drawing Vdd is 3x 12V batteries in series. Second step is to keep this 60 OHm load, and raise Vdd to 400V.
Well, my Class E sstc is a self-resonator oscillator, so it makes its own gate drive pulses from a DC-biased pickup loop under the primary.
You might like to take a look at the technique Steve Ward uses for his HF SSTC.
Try the LTC1799 oscillator chip instead of a 555.
http://i.ebayimg.com/t/1KHz-to-33MHz-Adjustable-Oscillator-Module-LTC1799-/00/$(KGrHqR,!jIE5eKtBB!9BOewH!3opQ~~_12.JPG
Interesting ways for mosfet driving! I think LTC is fine for me. I already ordered it! Thanks Tins.. :)
I have worked many times with Irfp460 and i never had problems using 555 + comparator for PWM driving. !2V pulses up to about 400KHz. It is my first attempt to drive it in MHz range. Well, will see!
Yes, keep us posted on your progress!
For good operation at HF you will need to use good layout and construction, a printed circuit board if possible but if not, then short, soldered wiring, not too many clipleads!
Also some 20 V "gate protection" zeners, back-to-back (or "front to front", I mean in series and oppositely oriented) and from gate to source, right at the mosfet pins, may help to protect your mosfet when you are hitting the gate with the 18V drive.
Hey Tinsel thanks for the zeners advice.
I finally found my mistake. Between 555 and MCP driver there was a nand gate in which two legs there was coming the same pulse from 555 with a small artificial phase difference, so to create a pulse as short as it could be. But, this was over-driving the driver up to a fatal level even if the input wasn't more than 4.97V. I still don't know why as nand gate is cmos and cmos is compatible for MCP input. But, after i had taken it out, the driver was working fine.
Thanks
Jeg
Good that you found your mistake.
Not so good that you didn't mention this NAND gate chip before when you were asking for help! 4011? 7400? What you get out from such a chip may not be the same pulse voltage level that you supply it from the 555, but more like your Vcc supply voltage.
The most of the times the problem is where i am the most sure of!!! I was so sure that the Cmos gate was ok, that i had put it out of discussion!! Anyway, i had supplied it from the same Vcc (LM7805) that 555 used. I can't think something that could create such a problem! It's output was in the driver's specification range...
Ah.. actually is a XOR gate 74hc86 but there isn't any difference. I discard it!!! :D
Well, at the frequency/risetime you are working with it's possible that stray inductances could create high-voltage spiky noise that the driver chip couldn't handle. Between your clock and your mosfet driver, keep leads as short as possible, use proper grounding technique, use a printed circuit board if possible, use bypass capacitors.
Since the direct output of the 555 clock is probably less abrupt in risetime than the output from the logic chip, ironically, it might be easier for the driver to handle because it makes less transient spikes.
hmm perhaps a low pass filter before the driver's input will solve this driver overdriving. Tnks for the advice
Have you ever worked with many mosfets in series for higher voltage switching?
Dear all
I attach a mosfet driver PWM circuit for discussion and learning purposes. I used MCP1406 for fast switching, even i will use it at Audio frequencies.
The circuit uses a 555 and a LM393 comp. for PWM. The timing cap and resistance of 555 will be a pot and few different caps for covering all the audio range with equal Ton and Toff pulse times. (50%). The comp changes the duration of the pulse from about 50%-100%. This is because MCP1406 is an inverting input.
First of all i 'd like to ask about the supply voltages of 555, 393, and 1406 chips. What if MCP1406 would be supplied by 18V and the other two by 5V or 12V. What would be the difference?
An other question is about the pull up resistor of 393 comp. I put a 1.8KOHm for allowing 10mA for the open collector at comp's output, and then 1,8M for allowing maximum 10μΑ for 1406 input. Is that a wrong consideration?
An isolated gate input with pulsed TRansformer also may be included. I intend to use it with a 1000V mosfet (FQA8N100C) or an IGBT at 1200V (HGTG27N120BN)
Any suggestion would be appreciated
Jeg
Here is a way for paralleling voltage regulators for higher current. I think i ll go this way for the supply of MCP1406. 3 regulators are enough for giving up to 6A peak current
http://www.instructables.com/id/Increasing-current-on-78xx-series-regulators/
Quote from: Jeg on November 15, 2013, 10:09:28 AM
..
First of all i 'd like to ask about the supply voltages of 555, 393, and 1406 chips. What if MCP1406 would be supplied by 18V and the other two by 5V or 12V. What would be the difference?
An other question is about the pull up resistor of 393 comp. I put a 1.8KOHm for allowing 10mA for the open collector at comp's output, and then 1,8M for allowing maximum 10μΑ for 1406 input. Is that a wrong consideration?
An isolated gate input with pulsed TRansformer also may be included. I intend to use it with a 1000V mosfet (FQA8N100C) or an IGBT at 1200V (HGTG27N120BN)
...
Hi Jeg,
On the supply voltages: first I would not use R1 and R2 dividers to reduce the 24V DC input. I have noticed your next post on considering more beefy supply solutions, that sounds a better way, though a single 15V regulator with a higher current pass transistor around it would do well. I say 15V instead of the 18V because the MCP1406 highest recommanded supply voltage is 18V and you intend to drive a MOSFET whose gate pin may easily receive higher than 18V voltage 'smacks' from the drain-gate dynamic capacitance and may cause harm (even if you protect the gate-source with a voltage limiting 18V Zener diode, you would need to use less than 18V pulses coming from the MCP1406). You may wish to use the LM317 adjustable regulator (also with a pass transistor) to lift the 15V closer to your 18V, let's say to 17V... ;)
For the 555 and the comparator IC I would use a common 12V regulator. The 1.8 kOhm sounds good, maybe a few kOhm more is still good because at this stage speed is not yet a question and less than 10mA can surely be allowed.
However, the series 10 MOhm is unnecessary because the max 10uA is meant to be taken by the MCP1406 itself when the input control voltage is 18V or less; putting this otherwise: the input pin of the MCP1406 is designed just to load the input voltage with a max of 10uA current, ok? So just omit the 10 MOhm resistor, maybe use just a few hundred Ohm or 1 kOhm or just connect the points directly.
Regarding an isolated gate input driver: it may be needed and perhaps the paper I uploaded in the MOSFET stack thread
http://www.overunity.com/13995/mosfet-stack-for-higher-breakdown-voltage/msg376695/#msg376695 helps you (a single toroidal core with a small OD coax cable (RG174U) wound on it would serve you well).
Gyula
After Gyula's suggestions on pwr supply, this is the improved circuit diagram.
Please feel free to add or discuss what it doesn't look right :)
Here is the isolated mosfet gate input through transformer. It is based on the pdf that Gyuila linked.
The test Transformer is made by 17 turns of bifilar wire around a tv flyback trans. ferrite.
Hi Jeg,
That schematic seems okay, C2 and C5 is to be mounted very close to the supply pins of the MCP1706.
One more thing: at the outputs of the MCP chip you show two 3 Ohm series resistors, this in fact increases the original output impedance of the chip during both the on and off states, maybe you wish to connect the output pins directly to each other and use a single 3 Ohm series resistor towards the gate of the MOSFET. Data sheet does not include info on this though.
Gyula
What i am thinking here is about the positive and negative pulses that feeds mosfet after the isolated transformer. The amplitude of both pulses would be the same. Dowesn;t need the negative one to be smaller in a certain range? Is it better to rectify the outgoing pulse before the mosfet?
Quote from: Jeg on November 16, 2013, 06:45:07 AM
...
The test Transformer is made by 17 turns of bifilar wire around a tv flyback trans. ferrite.
Well, perhaps the air gap is too wide, a much smaller gap would be better to further increase self inductance of the coax coil to reduce excessive load on the driver IC due to a smaller self inductance at the lower audio frequencies.
I just show your answer and and you are right. I will fix it on the schematic ;)
The gap is there by default for avoiding saturation on the tv flyback trans. I will try to put a piece of metal sheet between the legs...
Quote from: Jeg on November 16, 2013, 06:53:44 AM
What i am thinking here is about the positive and negative pulses that feeds mosfet after the isolated transformer. The amplitude of both pulses would be the same. Dowesn;t need the negative one to be smaller in a certain range? Is it better to rectify the outgoing pulse before the mosfet?
Well, I do not really know if there is a need for a smaller negative pulse amplitude in a certain range versus the positive pulse, (normally it does not?)
I do not think you need to rectify the pulse befor the mosfet.
Quote from: Jeg on November 16, 2013, 07:00:23 AM
The gap is there by default for avoiding saturation on the tv flyback trans. I will try to put a piece of metal sheet between the legs...
Yes that is okay but on the input side of the MOSFET you do not have such high input power which would bring the core towards saturation? The paper referred to much smaller ferrite toroid cores, your flyback transformer has got a much higher cross section area.
sorry i forgot this
I have this with a 10.000μ permeability. (Fair rite) but the cable is too thick for making 17 turns inside there. I will put something smaller and give it a try.
There is problem now that you wish to use the input transformer: the MCP chip may get burned the fist moment it is switched on because the DC resistance of the coax cable is but a few milliOhms, letting a quasi short circuit appear the chip output if the series 3 Ohm is there than it is the only resistance to limit the shorting current. To remedy this, a coupling capacitor of a few uF should be connected in series with the 3 Ohm to block DC current.
Revised Diagram after Gyula's proposals
- One Resistance 3 Ohm after MCP1406
-Electrolytic cap 4.7μF after the above resistance. For Frequencies above the audio range this cap should be smaller.
Jeg
Gyuila my new load inductor at mosfet's side is 20μΗ. At 500Hz minimum rate it will be like a shortcut. Is it a good method to put a resistor in series with the inductor? Can I get over it by just having a very short pulse through the pwm?
QuoteI have this with a 10.000μ permeability. (Fair rite) but the cable is too thick for making 17 turns inside there. I will put something smaller and give it a try.
Well, you could use normal enameled copper wire, twisting two 60-70cm or maybe a bit longer, d=0.3mm or so wire pieces together (3-4 twists/cm, not critical) and wind it onto that core. It would give enough isolation, no real need for a coax coil, or as an alternative, you could use thin plastic insulated copper wires and also twist them.
Quote
my new load inductor at mosfet's side is 20μΗ. At 500Hz minimum rate it will be like a shortcut. Is it a good method to put a resistor in series with the inductor? Can I get over it by just having a very short pulse through the pwm?
Well, the problem is that if you use a series resistor, then depending on its actual value, it will take most of the power as one member of a voltage divider and the other member of the divider is the coil with MOSFET. So the coil would actually receive a certain part of the input power only, which would be equivalent to a reduced supply voltage input.
(The IRF840 happens to have a max RDS
ON resistance of 0.85 Ohm and 32 Amper pulsed peak drain current (see its data sheet on the duty cycles in this respect) and if you use 24V DC supply the current may approach very easily the 32 A limit, especially if you tinker with the duty cycle. So the only solution is to use either a 50-60 Amper drain current rated device or just reduce the drain supply voltage to as low as 8-10V as a start if it is viable. Even so the correctly sized heat sink for the MOSFET is a must. See Figure 11 in the data sheet of the IRF840.
Quote
- One Resistance 3 Ohm after MCP1406
-Electrolytic cap 4.7μF after the above resistance. For Frequencies above the audio range this cap should be smaller.
Try to use 3 or 4 pieces of 2.2 uF 35V electrolytic capacitors in parallel to reduce the inner series loss resistance or even better use low ESR capacitors to reduce losses in the capacitors.
What do u think about this?
HGTG27N120BN
Continuous collector current 72A, pulsed 216A
Seems very good but it is expensive (9-10 USD apice)
Hi to all
For those that would like to build this driver, just pay attention on MCP1406/07 input pulse voltage. It needs to be in the same level as MCP's power supply voltage. If you supply MCP1406 with i.e 15V, then the input pulse has to be at 15V. In a different case i.e 15V pwr supply and 9 or 12V input pulses, the MCP runs as hot as hell.
I will change this on the schematic and i'll post it later.
I finally used 3X LM7815 in a parallel connection with diodes, capable for giving 3A continues current and 6A pulsed. It seems to work great.
Jeg
PWR Supply changed