Hi 🙂
I have build several Class-D amps in the past, with chips from TI, but also semi discrete. But always Full-Bridge designs with clock. (not self oscillating) I just wondered if anybody already tried an amp with a low power class D ic as modulator. Like a PAM8406 or MT6905.
Greetings
David
I have build several Class-D amps in the past, with chips from TI, but also semi discrete. But always Full-Bridge designs with clock. (not self oscillating) I just wondered if anybody already tried an amp with a low power class D ic as modulator. Like a PAM8406 or MT6905.
Greetings
David
"As modulator", as opposed to... what?
Both the PAM8406 and the MT6905 are "already" amplifier chips, so... Not 100% sure what your question actually is 🙂
Both the PAM8406 and the MT6905 are "already" amplifier chips, so... Not 100% sure what your question actually is 🙂
Oh, sry. 🙄
I meant to use it just to generate the PWM signal, which can be used then
to feed a more powerful H-Bridge. For example 2*IR2110 + Fets at >50V.
Greetings
David
I meant to use it just to generate the PWM signal, which can be used then
to feed a more powerful H-Bridge. For example 2*IR2110 + Fets at >50V.
Greetings
David
My thought was, if those chips reach thd below 0,5% they must generate a quite good Signal. All in all they are just an oscillator + Power comparator. Maybe ill give it a try.
🙂
🙂
Umm... No they're actually not 🙂 Not if by "they" you mean those two low-power class-D amp chips.
If you check the datasheets for those, you'll notice they also contain the MOSFET outputs ("already") 😉
http://www.maxictech.com/uploads/soft/201302/1_01160014.pdf
The giveaway here are the Rdson numbers on page 15. Rdson = on-state drain-to-source resistance, which is a characteristic of the output MOSFETs (looks like there are both P-channel and N-channel ones). The block diagram isn't too revealing, with the "modulation" black-box encompassing the output stage as well.
https://www.mouser.com/ds/2/115/PAM8406-247303.pdf
This other one's a little bit more detailed.
If you check the datasheets for those, you'll notice they also contain the MOSFET outputs ("already") 😉
http://www.maxictech.com/uploads/soft/201302/1_01160014.pdf
The giveaway here are the Rdson numbers on page 15. Rdson = on-state drain-to-source resistance, which is a characteristic of the output MOSFETs (looks like there are both P-channel and N-channel ones). The block diagram isn't too revealing, with the "modulation" black-box encompassing the output stage as well.
https://www.mouser.com/ds/2/115/PAM8406-247303.pdf
This other one's a little bit more detailed.
Hi BBC,
A very good idea and it really works.
It simplifies the headache of making a discrete modulator, triangle generator, preamp etc etc.
I have tried it with MAX4295 clocking at 250Khz with universal feedback and it works better than any discrete design. Simple BOM and compact.
Beast of luck for trials.
Ajazz
A very good idea and it really works.
It simplifies the headache of making a discrete modulator, triangle generator, preamp etc etc.
I have tried it with MAX4295 clocking at 250Khz with universal feedback and it works better than any discrete design. Simple BOM and compact.
Beast of luck for trials.
Ajazz
I remember some 11+ years ago that forum member BWRX used TPA2000D1 to drive a TAS5261 output stage.
http://www.diyaudio.com/forums/class-d/87534-texas-instruments-tas5261-16.html#post1039161
http://www.diyaudio.com/forums/class-d/87534-texas-instruments-tas5261-16.html#post1039161
Hi Ajazz,
Can you post some scheme of the feedback implementation at this case? How the "modulator IC" already have a internal loop feedback to drive directly a speaker , did you put the feedback directly to the diferential input of IC? Don't have issues with the clock stability making this?
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