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ADuM3190 increase output voltage in LTSpice

Category: Software
Product Number: ADuM3190
Software Version: LTSpice XVII

I'm simulating in LTSpice an ADuM3190 to implement an error amplifier, but I need to increase the output voltage of the component.

Doing some testing in simulation, it is implemented at the left side of the component a voltage follower with a triangular wave (0-8 V), as it can be seen in the next figure, and in the right side of the component is introduced a pull-up resistor at 15V with the objetive to increase the output voltage, as is mentioned in the datasheet.

But, after simulating the circuit, it seems that the output is clamped to 2.62V in EAout and 6.85V in EAout2. It could be a problem in the implementation of the circuit or in the other hand, there is some kind of error in the Spice model of the ADuM3190?

The simulation file can be downloaded in this link:

Thanks in advanced.

  • Hello,

    As you are using a buffer configuration, the input range of pin +IN is the same as the input common-mode range of the op. amp. From the datasheet, this is: 0.35 V to 1.5 V. Therefore, by injecting >2.5 V in pin IN+ the input range would be exceeded, which is not recommended. Furthermore, whereas EAOUT2 is an open-drain output specified to work with a pull-up resistor, EAOUT is not, so a pull-up resistor is not recommended for use with EAOUT. When using EAOUT2 pin the datasheet specifies the typical working range of 0.3 V to 5.4 V, for your supply voltage VDD1=15 V. An 8 V input would cause to exceed this range.

    Looking at your simulation: EAOUT and EAOUT2 clamp at 2.6 V and 6.8 V respectively when the volage on COMP and IN+ is 2.6V. This is consistent with the gains specified on the datasheet, respectively: 0.9 to 1.1 from COMP to EAOUT2, and 2.34 to 2.86 from EAOUT to EAOUT2. Therefore, there is no indication of error from the LTSpice model.


    Juan Carlos

  • Hello,

    Thanks for the clarification, then I will have to adapt to the input range.

    Best Regards