Dear Friends,
I am the hardware engineer in the company and I have not too much experience in sound designs!!
I have testing the single supply circuit that is inside the lm1875 datasheet, and it sounds ok.
I have to put all the circuit in a box with and speaker and we have to test that this box is acording EMC rules.
Do you know if there is any input/output EMC filter to add in the single supply circuit above mentioned?
What is the best way to desing the properly Heat Sink for the LM1875?
Thanks in advance!!!
Alcuemar
I am the hardware engineer in the company and I have not too much experience in sound designs!!
I have testing the single supply circuit that is inside the lm1875 datasheet, and it sounds ok.
I have to put all the circuit in a box with and speaker and we have to test that this box is acording EMC rules.
Do you know if there is any input/output EMC filter to add in the single supply circuit above mentioned?
What is the best way to desing the properly Heat Sink for the LM1875?
Thanks in advance!!!
Alcuemar
Are you talking about interference or susceptibility?
For lowering conducted susceptibility(+interference) you could add one of those "AC-input-filter":
example
Those sometimes can be had quite cheaply at buyouts.
For improved susceptibility I´d definitely put it in a metal case,
that is properly grounded.
Otherwise you just have to finetune your PCB-layout and schematic so that the chip doesn´t oscillate.
(see datasheet and/or check the forums)
Don´t see many other problems that could occur.
The chip has a good PSRR and seems quite easy to handle.
greets
Jens
PS.: Don´t know about EMC rules being different in other countries so maybe you could kindly ask other commercial amp designers here.
You should find some searching around ;-)
For lowering conducted susceptibility(+interference) you could add one of those "AC-input-filter":
example
Those sometimes can be had quite cheaply at buyouts.
For improved susceptibility I´d definitely put it in a metal case,
that is properly grounded.
Otherwise you just have to finetune your PCB-layout and schematic so that the chip doesn´t oscillate.
(see datasheet and/or check the forums)
Don´t see many other problems that could occur.
The chip has a good PSRR and seems quite easy to handle.
greets
Jens
PS.: Don´t know about EMC rules being different in other countries so maybe you could kindly ask other commercial amp designers here.
You should find some searching around ;-)
Unfortunately not.
I´ve got some around but wouldn´t know exactly what to look for.
Guess they all damp those interferences to a certain extent...
That said: there are quite a few amplifiers out there without those,
so passing EMC norms shouldn´t depend on those filters.
Get the circuit properly working; metal case, proper grounding
and do some tests.(oscillations?, conducted EMI-tests)
If there´s any problems go from there.
What do you mean exactly with EMC protections?
Do you know which tests the amplifier has to go through?
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