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THEORY OF OPERATION

GND

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

R

R

R

V

OUT

CODE

65536

(1)

_

+

OPA277

V+

V−

15 V

−15 V

GND

DAC8811

U2

U1

DAC8811

SLAS411B – NOVEMBER 2004 – REVISED FEBRUARY 2007

The DAC8811 is a single channel current output, 16-bit digital-to-analog converter (DAC). The architecture,

illustrated in Figure 17, is an R-2R ladder configuration with the three MSBs segmented. Each 2R leg of the

potential by the use of an external I/V converter op amp. The R-2R ladder is connected to an external reference

impedance to the external reference of 5 k

Ω ±25%. The external reference voltage can vary in a range of -15 V

Figure 17. Equivalent R-2R DAC Circuit

Equation 1:

also change. Because of this, the external I/V converter op amp must have a sufficiently low offset voltage such

large offset voltages can produce INL errors in the transfer function of the DAC8811 due to offset modulation

versus DAC code. For best linearity performance of the DAC8811, an op amp (OPA277) is recommended

Figure 18. Voltage Output Configuration

8

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