During startup, output of primary amplifier (eg EAout2) is at high level when VDD2 is lower than 3V.
How to avoid this behaviour when ADUM3190 is included in a regulation loop.
Sartup is impossible due to the wrong information sent to PWM controller.
Dan: I have received a response from the designer of the ADuM3190:
The EAout2 is the open drain output, only a pull down device is included in the part. When supply is not ready (i.e. vddx is less than 3V), the pull down device is off, so the output is designed to be high. A rough method to change the output state is to add another smaller pull down resistor at EAout2. During vddx is less than 3V, the EAout2 will be simply the resistor divider output, which can be designed to a smaller voltage.
EAout output is designed to be high impedance when vddx is less than 3V, which can be configured to high or low by a pull up resistor or pull down resistor as desired. Note that the voltage range of EAout is less than EAout2.
I have asked the designer about your issue with the ADuM3190 and will let you know when I have a response. Can you send a circuit diagram?
Thanks a lot for your answer. My mockup is working correctly now.
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