| 摘要 |
An electrical circuit for measuring an analog voltage from an external sensor comprises an a/d converter, first and second single-ended power supplies and a voltage reference. The a/d converter includes a differential input having a relatively high-voltage side and a relatively low-voltage side. The differential input is adapted for receiving a differential signal from an external sensor. The first single-ended power supply provides power and signal ground to the a/d converter. The second single-ended power supply is floating with respect to the first single-ended power supply and provides current to an external sensor, such as a loop powered transmitter. The voltage reference is powered from the first single-ended power supply and provides a common mode voltage bias to the differential input of the a/d converter. |
