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12-Bit Serial Daisy-Chain D/A Converter

8143

07.23.03 REV 3

Analog/Digital Division

The transfer function for the 8143 connect is the multiplying mode as shown in Figures 16 and 17 is:

where AX assumes a value of 1 for an “ON” bit and 0 for an “OFF” bit.

The transfer function is modified when the DAC is connected in the feedback of an operational amplifier as shown in

Figure 20 and is:

The above transfer function is the division of an analog voltage (VREF) by a digital word. The amplifier goes to the

rails with all bits “OFF” since division by zero is infinity. With all bits “ON”, the gain is 1 (±1 LSB). The gain becomes

4096 with the LSB, Bit 12, “ON”.