AnsweredAssumed Answered

Power supply problem about AD8557

Question asked by hpkamen on Nov 6, 2015
Latest reply on Nov 9, 2015 by Emman.A

i am suing AD8557, having some issues showing below,

could you please help clarify it.

Questions are as follows:

 

1, the input signal frequency: 50mV,20kHz;

2. the data says the power supply should be 2.7~5.5V , but why some Web site says we can use +-2.5V? And the data also shows some figures with +-2.5V power supply

 

3, if i use 5V single power supply, when put the input signal, there is no output wave;

 

4, If i use +-2.5V power and want to get a output signal ,the input signal must  bias voltage to  0.5V

 

5, if i use +2.5V, i could not control the gain, and it always shows gain=8

the measured waveform and digital signals and schematic pictures shown below, please help me see where is the problem? Thank you

原理图.jpg

数字“0”的波形(脉宽1.4uS).jpg

数字“1”的波形(脉宽78uS).jpg

第一级增益设置为:127.jpg

偏置设置为:127.jpg

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