| 摘要 |
A circuit in an integrated circuit having input terminals coupled to a resistor network for selecting one of multiple digital states includes a tri-state circuit, a multiplexer, a comparator and a control circuit. A DAC can be used to generate a set of comparison voltage levels. The circuit detects the power connection and the resistance values of at least two resistors in the resistor network having a third resistor of fixed resistance. The resistance values for the two resistors are selected from a set of resistance values corresponding to the number of digital stages which can be programmed on each terminal. The power connection option doubles the number of digital stages to be programmed on each terminal. Thus, multiple programming states can be assigned to each control pin of an integrated circuit and a large number of programming states can be programmed using a small number of control pins.
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