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Before going into the device specifications, consider a common current sensing system. In a current sensing system for AC signals, bidirectional currents flow through the shunt resistor. Since the current is bidirectional, the signal swings below ground, which is a problem when it is connected to a unipolar input ADC. Therefore, a voltage is needed to level shift the signal in order to meet the input requirements of a unipolar input ADC. There are a variety of methods for supplying power (V+) and reference voltages (VREF, or VBIAS) to a system. The image on the right side of this slide shows a conventional solution with a reference, voltage divider, and an op-amp buffer. However, this solution introduces errors caused by resistor mismatch and op-amp offset. That means in a low-drift high precision system, the discrete solution cannot be satisfied. To fix this problem, a new solution exists, simply use the REF2025 to supply both the reference voltage and bias voltage to the current sensing amplifier. This is a one-chip solution, with dual-output, low drift tracking and low power consumption. The table below shows the comparison between the discrete solution and REF2025. To generate the same dual outputs (3 V and 1.5 V), and to achieve similar tracking performance, the REF2025 family has higher initial accuracy, lower temperature drift, smaller total errors, better matching between dual outputs, and achieves all this while still being a 30% lower cost solution. Additionally, the REF2025 has complete application-specific reference design examples known as TI Designs which cover these two solutions.
