Audio Codec info on STM32f469-Disco

[ashutoshr]

I'm using a STM32F469i- discovery board for developing a prototype & would like to use the Audio DAC feature in it and it is given in the datasheet that one set of pins (15 & 16 in CN12). I checked this discovery board's and also the controller's datasheet but were unable to find any information regarding the resistance of the speaker that can be connected to the pins. Will this pins(15,16 in CN12) be able to comfortably drive a 8 ohm speaker, having watt-rating less than 1 W? Would love to get some insights on this

Cheers, Have a great day

[Andrew Neil]

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@ashutoshr wrote:

I can safely drive the speaker using only STM32f469  since it has a audio codec integrated.

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No, it doesn't!

As already explained, the STM32f469  does not have any audio CODEC integrated.

The audio CODEC on the STM32f469-Disco board is external to the STM32f469 chip. 

[SofLit]

The voltage indicated is the power supply of the PWM output stage of the codec.

You need to read the datasheet of the Codec:

The power supply of the codec is 3.3V for this disco board: 

[Andrew Neil]

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@ashutoshr wrote:

so what voltage value is provided by the pins 15 & 16, I have to get it clarified from the Cirrus logic people and accordingly decide on the power and ohms? 

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See the schematic posted by @SofLit earlier - it shows you that CN12 pins 15 & 16 are directly connected to the Cirrus logic SPKR_OUTA+ and SPKR_OUTA- output pins:

so these are solely a function of the Cirrus logic chip - nothing to do with the Disco board or STM32 microcontroller.

[ashutoshr]

Sorry I have not framed the sentence properly, but yeah I didnt mention as in the IC there, I was meaning the STM32 development board had an audio codec, so yeah that wasnt my doubt, my doubt was that since the audio codec is being controlled by the STM32f469 chip, I was wondering what would be the voltage output peak and rms at those 2 pins so that I can accordingly choose an impedance for the speaker.

Hope my question is clear to you now. 

[ashutoshr]

I mean that I understood so only I have asked since the PWM of cirrus logic is powered by 3V3, I should then  consider only 2.5V as 3V3/1.414 is roughly 2.3V rms..so while choosing a 4 ohm speaker I have to choose a speaker that is rated say 0.5W then the speaker will be safely driven. 

Have I understood it correctly now or am I still messing this up(sorry if I am, please help me)

[ashutoshr]

 since the PWM driver of cirrus logic is powered by 3V3, I should then  consider only 2.5V rms as 3V3/1.414 is roughly 2.3V rms..so while choosing a 4 ohm speaker I have to choose a speaker that is rated say 0.5W then the speaker will be safely driven. Is my choosing of the speaker correct

Have I understood it correctly now or am I still messing this up(sorry if I am, please help me)