Q: Why does the ADuM3190 have two Error Amp Output pins?
A: The ADuM3190 has an EAOUT pin 6 which has an output voltage specified to 2.4V and an EAOUT2 pin 7 which is specified to 5.0V when EAOUT2 is used with a pull-up resistor to a 10V to 20V supply. The EAOUT2 pin provides a higher voltage to help drive the COMP pin of a PWM controller which may require 5V. The internal circuits of the ADuM3190 run off internal 3.0V regulators, which provide stable operation and are powered from an external VDD supply voltage that can range from 3V to 20V. This is why the EAOUT pin 6 is limited to less than 3V. The EAOUT2 pin has an open drain circuit which is used with an external pullup to connect to a VDD supply voltage of 3V to 20V, which is how EAOUT2 can be rated to 5.0V. An internal diode at the EAOUT2 pin clamps at about 5.5V to protect it from the higher VDD voltages when used with a pullup resistor. See the attached circuit for details about the EAOUT and EAOUT2 pins.