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LM4550B: Concerns for LM4550BVHX/NOPB AC 97 codec in our design.

Amrutha k n
Prodigy 40 points
Part Number: LM4550B

Hi Experts

Please find below details that I am concerned in using the TI LM4550BVHX/NOPB AC 97 codec in my design to replace the STAC9753AXTAED1X AC 97 codec from Tempo Semiconductor.

I found that the AVDD used on your codec has a range from 4.2 to 5.5V and hence may need a 5V supply designed.  

The inputs coming to the codec from microphone and Telephone lines are all at 3.3V levels as the existing codec had 3.3 AVDD supply. I would prefer not to change the supply voltages on these inputs and outputs of the Codec but still have 5V provided for AVDD supply pins.

I would like to understand what is the impact of this modification ( using AVDD at 5V and others circuits at 3.3V, including inputs to codec) in the design on system performance?

Also, we can see the Analog Quiescent current of 53mA listed in the datasheet, what is the meaning of this parameter? if we design a power supply for 5V, what would be the current value for which we need to design it?

Thank You

  • 0
    TI__Mastermind 29755 points

    HI,

    What inputs are you referring to that are all 3.3V? The analog input voltage is 1 Vrms and the DVDD is 3V-5.5V for the digital IO. 

    If the levels are within the spec then that's fine.

    Quiescent current is when the supply is not driving any load, the 53mA is with 5V supply.

    Regards.