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Question asked by jolu on Jul 7, 2014
Latest reply on Aug 13, 2014 by bkennedy



I'd like to use the ADuM3190 in a DC/DC converter project. For this purpose, I'm trying to build a simple PSpice model of the ADuM3190.

What I need is some information about the DC transfer characteristic of this device.


Using my Pspice model I have build the following circuit, where I wired the input OPAmp as a subtractor:


Sweeping V1 provides the following DC transfer characteristics for EAout and EAout2 (colours correspond to the colors of the voltage probes shown above):



Does anyone know if these characteristics are correct ?



Second question:


The subtractor shown above is used in a feedback path of a control system to measure the output voltage of the DC/DC converter. Controlled is not the output voltage but the output power of the converter. It turns out, that the regulation of the output power is very sensitive to the min. output voltage of the ADuM3190 (specified as 0.4V maximum in the datasheet for the EAout output). Assuming a possible variation of the min. output voltage of EAout between 0V and 0.4V from device to device, simulations show, that the voltage measurement error due to this variation leads to strong deviations in the output power of the converter from the desired reference power value.


Is there any solution to such a problem ? I think an optocoupler solution to measure the output voltage is a bad idea too because of the strong variations in current transfer ratio from device to device and with age and temperature. Any ideas how to measure exactly the output voltage (isolated) in a converter ? I thought the ADuM3190 to be the perfect solution.


Thanks in advance.