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AD8032 output impedances

Dear Mr or Mrs,

Could you please tell what are the output impedances of the AD8302 for VMAG and VPHS outputs?

regards

  • Greetings victor_guillot,

    I can't give a precise answer, however datasheet Figure 1 on page 5, Circuit B, shows an internal resistor of 25 Ohms with the main outputs. Add to that the common-emitter class AB output stage inherent output impedance. The total is likely perhaps 75 Ohms, rough estimate. But kindly note, whatever the total is, the effective output impedance becomes drastically reduced by closing the voltage feedback path around the internal output buffer. This happens when MSET / PSET connects to VMAG / VPHS outputs respectively. Output impedance reduction also occurs when output feedback dividers are used, such as datasheet figures 8 & 9, although to lesser degree. In summary, for typical configurations utilizing feedback, we would expect the small-signal, low-frequency, effective output impedance to be considered negligible whenever the datasheet page 2 output current specification of 8mA source/sink is adhered to. Hope this helps answer your question.    -Bruce H. 

  • Hello,

    Thanks for your answer.In my case, MSET connects to VMAG and also PSET to VPHS.So it is not necessary to add a buffer between outputs MSET/VMAG and ADC of a micro controller for example.

    Regards