|YDA137-AZ||STEREO 5W DIGITAL AUDIO POWER AMPLIFIER|
|YDA137-AZ Datasheet PDF : 20 Pages |
■Description of functions
●Digital Amplifier Function
Amplifier function block diagram
Amplifier Section of YDA137 is composed of the first operational amplifier stage and the latter digital amplifier stage.
Gain of the first operational amplifier can be set by connecting input resistor (RI) and feedback resistor (RFB) externally.
In digital amplifier stage, digital amplifier output is feed-backed to the modulation circuit, and low distortion rate is
Digital amplifier output is connected to a speaker through the 2nd-order low-pass filter consisting of inductance (Lo) and
capacitance (Co). This eliminates carrier frequency content existing at the digital amplifier output, consequently only audio
signal is sent to a speaker.
Gain of the first operational amplifier can be calculated by the following formula. Gain of aｎ internal digital amplifier is
First operational amplifier stage
Digital amplifier stage
20×log(RFB/RI) dB (Using RI and RFB. Conditions：RI >2kΩ)
In the application circuit example, RI=33kΩ, RFB=39kΩ, total gain (Av) can be calculated by the following formula.
In this setting value, input sensitivity is 1Vrms, the maximum output could be obtained at 1Vrms input.
When input sensitivity is set to 150mVrms, it is set as RI=4.7kΩ and RFB=39kΩ.
Av(dB) = 20×log(39/33) + 8
= 9.5 (dB)
In gain setting of the first operational amplifier stage, it is necessary to obey the restriction that is described in the “Pop
Noise Rejection Function.” In addition, feed back resistor (RFB) needs to be 10kΩ or over because of the restriction on
operational amplifier drive capability.
|Direct download click here|
|Share Link :|