The TI E2E™ design support forums will undergo maintenance from Sept. 28 to Oct. 2. If you need design support during this time, contact your TI representative or open a new support request with our customer support center.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA1620: Issues wih paralleling INA1620

Part Number: INA1620
Other Parts Discussed in Thread: OPA1622

Hi there !

I have a question regarding paralleling two INA1620 amplifiers according to sboa352 article. 

I want to connect the output of LPF based on the Figure 40 of AK4490 datasheet with paralleled INA1620 amp.

Could you please tell me which INA1620 input should the output from LPF be connected to? If it goes to one of the inputs (inverting or noninverting), then what should be done with the other input left?

Regards,

  • Hello Jahongir,

    See the TINA circuit schematic I show below. I created it using the OPA1622 instead of the INA1620 so that it is easier to see its relation to the AsahiKASF, Figure 40, filter circuit. The filter R and C component values have been scaled to utilize the precision, 1 kilohm resistors internal to the INA1620. R2, R3, R7 and R8 are the INA1622 internal 1 kilohm resistors .

    The response is exactly same as obtained with these components as in the Figure 40 circuit, fc 99.2 kHz and Q = 0.7. The parallel OPA1622, or INA1620, connection is provided in the schematic.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

    OPA1622_diff_in_LP_02.TSC

  • Hello Thomas,

    Thanks for providing TINA circuit schematic. Sorry, I think you got me somewhat wrong. Let me explain it in more detail. I have a portable mp3 player based on AK4490 DAC with External LPF given in Figure 40 of the named datasheet. My goal is to use 2 parallel INA1620 as a headphone amplifier, without changing the LPF schematic. The LPF "analog out" will be connected to paralled INA1620, so my questio was which input should the LPF output go to. As I understand it should connect to one of the INA1620 inputs (inverting or noninverting), and if so what happens to the other input and how the final schematic of parallel INA1620 will change. 

       

  • Hi Jahongir,

    It wasn't apparent that you had the post-DAC active filter already in place. The solution I provided incorporated the filter into the INA1620 configuration That would be desirable if an additional op amp wasn't available for the post-DAC active filter.

    You can take the Analog Out from the post-DAC active filter and drive either one of the two INA1620 "Audio In" inputs, the (+) or (-) points shown in the circuit above. Driving the inverting input inverts the input signal at the output, while driving the non-inverting produces the same output as the input.

    If you drive the INA1620 inverting input, the resistors and cap on the non-inverting input are not required. Just simply ground the op amp "A" non-inverting input. If you decide to drive the non-inverting input, ground the (-) point on the 1 kilohm input resistor.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • Thanks a lot for detail explanation. Now I have two options to go with.

    Best regards,