Datasheet ADuM3190S (Analog Devices) - 10

ISOLATED AMPLIFIER CIRCUIT OPERATION Figure 5 shows an isolated amplifier circuit. In this circuit, the input side amplifier is set as a unity-gain buffer so that the EAOUT output follows the +IN input. The EAOUT2 output follows the EAOUT output, but with a voltage gain of 2.6. This circuit has an open-drain output, which must be pulled up to a supply voltage from 3 V to 20 V using a resistor value set for an output current of up to 1 mA. The EAOUT2 output can be used to drive up to 1 mA to the input of a device that requires a minimum input operation of 5 V. The EAOUT2 circuit has an internal diode clamp to protect the internal circuits from voltages greater than 5 V. The gain, offset, and linearity of EAOUT and EAOUT2 are specified in Table 1 using this test circuit. When designing applications for voltage monitoring using an isolated amplifier, review these specifications, noting that the 1% accuracy specifications for the isolated error amplifier do not apply. In addition, the EAOUT circuit in Figure 5 is shown with an optional external RC low-pass filter with a corner frequency of 500 kHz, which can reduce the 3 MHz output noise from the internal voltage to the PWM converter.