Bipolar Mode

Versal ACAP System Monitor Architecture Manual (AM006)

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1.3 English

The analog inputs can accommodate analog input signals that are positive and negative with respect to a common mode or reference. To accommodate these types of signals, the analog input must be configured to bipolar mode. All input voltages must be positive with respect to analog ground (GND). When bipolar operation is enabled, the differential analog input (VP–VN) can have a maximum input range of ±0.5V. The common mode or reference voltage should be between 0.5V and 0.6V in this case. The SYSMON data format accommodates both positive and negative signaling, so a sign bit is always incorpoated into the results register, allowing a common format between unipolar and bipolar samples. See the following figure.

Figure 1. Bipolar Input Signal Range

The bipolar input mode also accommodates input signals driven from a true differential source, for example, a balanced bridge. In this case, VP and VN can swing positive and negative relative to a common mode or reference voltage (see the following figure). The maximum differential input (VP–VN) is ±0.5V. With maximum differential input voltages of ±0.5V and assuming balanced inputs on VN and VP, the common mode voltage must lie in the range 0.5V to 0.6V as shown in the figure below.

Figure 2. Differential Input Signal Range