OPA189: Drive ability for AMC1306

Hi Ogasawara,

The input structure of the AMC1306 consists of chopped-stabilized differential amplifier; accepting differential signals, targeting shunt resistor measurements and isolated voltage measurements at the +/-250mV or +/- 50mV range.  The AMC1306x25 has an input voltage range of +/-250mV with a differential input impedance of 22kOhms, and the AMC1306x05 has a range of +/-50mV and an average input impedance of 4.5kOhm.  

The OPA189 is a 36V, 14-MHz amplifier, capable of driving the input impedance of the AMC1306.

However, on the post you mention you are measuring a single-ended signal.  What is the amplitude/frequency of the single ended signal that is being measured and what is the voltage level or common-mode with respect to the AMC1306 AGND pin?

One concern, is that the AMC1306 can withstand an absolute maximum input voltage rating of AVDD+0.5V (from Absolute Maximum Ratings Table 7.1), or a maximum voltage around 5.5V without damage. Since in this case, the AMC1306 input is being driven with the OPA189 36V amplifier; the amplifier could potentially produce a large voltage that could damage the inputs of the AMC1306 .

If you can please provide a detailed schematic including the information of the sensor or signal you are trying to measure, we could provide other suggestions.

Thank you and Best Regards,

Luis Chioye