If i use a MAX628 mosfet driver to a class d amp project, do i still need a level shifter on the high side input ?
If so, how is a level shifter made ?
If so, how is a level shifter made ?
Simply use a 6N137 optocoupler, but you will need a mosfet driver for each mosfet..
Fredos
www.d-amp.com
Fredos
www.d-amp.com
The MAX628 is a dual mosfet driver, one inverting and one non inverting.
Could i use optocouplers from like a smps ?
Could i use optocouplers from like a smps ?
Bad move with your IC...Use and inverting with the 6N137 and non-inverting with the lower side..
Fred
www.d-amp.com
Fred
www.d-amp.com
Hum ?
I don´t fully undterstand what you mean ?
What was a bad move ? Atleast the MAX628CPA IC´s are free samples.
I don´t fully undterstand what you mean ?
What was a bad move ? Atleast the MAX628CPA IC´s are free samples.
You cannot drive upper and lower mosfet with that single chip, you will need 1 for upper mosfet and 1 for lower...If I understand that you was planning to use this chip for high side and lo side driver..
Fredos
Fredos
As the datasheet makes obvious at first look, the ICs of that family (MAX626/627/628) are plain dual gate drivers, with both halves sharing the same power supply pins. Thus, there is no way in which you could drive a half-bridge-like class D output stage with one of these ICs.
Not only level shifting is required, but also independent or floating gate buffers are. You can either design a discrete solution, or use an IC having all those features built in, like IR2112, IR2110 or IR2113.
Also, there are standard and fast optocouplers like 6N137 whose practical propagation delay is in the range of 50ns. However, be very careful when using optocouplers because they don't provide perfect AC isolation but only DC isolation. There are internal capacitances between the input and the output sections of the IC that will disturb the state of the output if a certain common-mode dV/dt slope is exceeded during switching transients. You will find those dV/dt inmunity ratings on datasheets, and even in the best optocouplers from Avago (formerly Agilent or HP) the rated dV/dt (up to 15KV/us) may become quite short considering the fast rise and fall times involved in class D (expect something like 100V in 40ns or less). Indeed, I can tell that simple optocouplers like 4N25 are extremely easy to disturb.
I feel that you should learn more about switching circuits before starting class D experimentation, otherwise plenty of component blowing disasters may arise.
Not only level shifting is required, but also independent or floating gate buffers are. You can either design a discrete solution, or use an IC having all those features built in, like IR2112, IR2110 or IR2113.
Also, there are standard and fast optocouplers like 6N137 whose practical propagation delay is in the range of 50ns. However, be very careful when using optocouplers because they don't provide perfect AC isolation but only DC isolation. There are internal capacitances between the input and the output sections of the IC that will disturb the state of the output if a certain common-mode dV/dt slope is exceeded during switching transients. You will find those dV/dt inmunity ratings on datasheets, and even in the best optocouplers from Avago (formerly Agilent or HP) the rated dV/dt (up to 15KV/us) may become quite short considering the fast rise and fall times involved in class D (expect something like 100V in 40ns or less). Indeed, I can tell that simple optocouplers like 4N25 are extremely easy to disturb.
I feel that you should learn more about switching circuits before starting class D experimentation, otherwise plenty of component blowing disasters may arise.
What about SC1205CS for mosfet drivers ?
Will they work ? The datasheet does say class d amplifiers.
Tho i have not found any place that sells them 🙁
Anyone have a few ?
Will they work ? The datasheet does say class d amplifiers.
Tho i have not found any place that sells them 🙁
Anyone have a few ?
Look good, but power supply limted to abou 18V if you use 12V bootstrap voltage...Good for experimentation!
fred
www.d-amp.com
fred
www.d-amp.com
That IC includes a floating high side driver (what you should look for) but has very low voltage ratings. It's intended to drive logic level MOSFETs with 5V applied to the gates, and the absolute maximum voltage that can be switched is 25V.
Keep searching.
Also, you can still find some application for the MAX628 samples. For example you may just use them as single gate drivers (allowing to conveniently choose between the inverting half or the other half), together with an external level shifter for the upper side that may be as simple as one or two transistors.
Be creative, and check carefully the datasheets before ordering anything!
Keep searching.
Also, you can still find some application for the MAX628 samples. For example you may just use them as single gate drivers (allowing to conveniently choose between the inverting half or the other half), together with an external level shifter for the upper side that may be as simple as one or two transistors.
Be creative, and check carefully the datasheets before ordering anything!
Maybe you have mosfet drivers that are similar to SC1205CS but made for standard gate mosfets, or know the part number of one ?
HIP4080, IR2110, IR2010, IR2011, etc... but non of them are so fast as SC1205CS or a single low side driver.
"Only for qualifield designers"Tekko said:
They are not that expensive, so why dont you just order some.
Alittle too expensive as 2-3 of these may blow up before the amp starts working.
Tho i have found a schematic here that i gonna go with.
It has not left the editor/simulator yet tho. Maybe the Author of the schematic has comments about it ?
Tho i have found a schematic here that i gonna go with.
An externally hosted image should be here but it was not working when we last tested it.
It has not left the editor/simulator yet tho. Maybe the Author of the schematic has comments about it ?
DIY is a hobby, you must pay for it.
Do You say it's expensive? In Hungary HIP4080 costs 1% of average monthly incoming! How about You?
Do You say it's expensive? In Hungary HIP4080 costs 1% of average monthly incoming! How about You?
Look for IR2112, it's almost the cheapest one in its class, altough it requires output buffer transistors (or IC) for most applications.
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