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SSM2305 Audio Amp Input Range

Dear Community,

What is the input range on the SSM2305?  The single supply is 4V.  The signal swings 3Vpp.  I appreciate that this is much larger than the normal "audio" signal.  :-)

Thanks in advance,


  • Hi Harry,

    Thank you for the quick reply.

    I saw in the datasheet that Vcm range is (Vdd-1) - 1 - (2V with a 4V rail).

    As an "audio" amp, I was wondering if Vp-signal is assumed to be about 0.5V:

    @ Vcm = 3V, I could go as high as 3.5V +/-

    @ Vcm = 1V, I could go as low as 2.5V +/-

    I am spoiled by opamps with rail to rail inputs and didn't want to leave any input range on the table.  :-)

    Vcm = 1/2 rail, Vp-signal = 1V it is.



  • Hi Harry,

    We are on the same page.  I was just surprised that the input voltage range is only (Vdd - 1V) to 1V.  That would explain the 6dB curves in the datasheet.  My pre-caffeine typing this morning (1.0V - 0.5V = 2.5V) probably raised the noise floor. 

    Operating Point:

    Vcm = 1/2Vdd = 2V, Vsignal-p <= 1.0V and gain set at 6db with external resistors.


    To answer your question, the load is a small 3W, 4 ohm speaker.