Active Elevated Rail Hi side Bootstrapping Technique for IR2110

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#41
darkfenriz said:
Kanwar
Why not just add a voltage source to a source of upper mosfet i.e. parallel to normal bootstrap cap?
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You mean to say completely isolated floating 15V referenced to source, it could be done very easily, but the floating supply then would become a stable source of great EMI radiation inferno!!!
 
#44
Indeed 2.2u will almost enough to heavy clipping on the very low frequency, though ir2110's typical -UVP treshold is 8.3V@75C (9.5V worst case), and Vbs static idle current 350uA (worst case), hence 12V[Vdd, no more if fastest switching is needed]-.6V[diode's drop]-50mV[to single charge 100-200nC old hat MOSFET]-9.5V=1.85V; 2.2uF*1.85V/350uA=11.6mS i.e. 43hz 100% clipping ok, so would be the best choice >4.7uF yet.
 
#45
darkfenriz said:
Why, even decoupled?
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You cannot decouple this w.r.t. ground, you have to use a common mode choke to decouple the floating voltage source....

phase_accurate said:
I was once thinking of the watchdog thingie as well but I like the approach of constantly powering the high-side driver better.

Regards

Charles
Click to expand...

Thanks for the vote of confidence!Sir

The watchdog, The chargepump, The fully isolated floating supply each one is having there own merits and demerits, but my elevated high side bootstraping technique is most simple to do and easy to achieve with the required results so far.....


Regards,
Kanwar
 
#46
Workhorse said:

but my elevated high side bootstraping technique is most simple to do and easy to achieve with the required results so far.....
Click to expand...

Really? you think so? Maybe in DC convertors with const duty cycle =1 your technique adaptable, but in audio range amp it has more disadvanatage, than benefits...imho 😉
I suppose the case, that transform your amp to smoke generator differ from version with hi side driver problem.
 
#48
Guys, what about you talking? I've just check it in the MC, it's completely wrong. See attachment, where my mistake? :cannotbe:
 

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#52
I think that the pass transistor is going to have a really hard time handling the high dV/dt switching transients without conducting more current than what it is expected to. Also, the bias resistor has to provide enough current to bias the zener and the pass transistor with only 10V across but it also has to be able to whitstand the full 200V supply across it too, which seems like a big compromise...
 
#56
No, no, no and no again ! You would only have to supply the quiescent current of the driver. The pulse is still supplied by a small bootstrap cap as usual. The thingie is just there to prevent undervoltage lockout for any arbitrary clipping situation.

Regards

Charles
 
#59
Why not use standard bootstrap and the circuit of WorkHorse only when output are near voltage rail? More efficient and less dissipative! Or like I use in some serie of amplifier, a bootstrap circuit with a 555 charge pump just to witsthand clipping condition...More efficient! 4 watts of lose is too much in a class d amplifier. The trick is only to find a way to hold voltage of hight side at clipping...

Fredos
 
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