www.ti.com

THEORY OF OPERATION

V

OUT

CODE

16384

(1)

GND

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

2R

R

R

R

_

+

OPA277

V+

V−

15 V

−15 V

GND

DAC8801

U2

U1

DAC8801

SLAS403A – NOVEMBER 2004 – REVISED DECEMBER 2004

The DAC8801 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 -10 V

Equation 1:

Figure 17. Equivalent R-2R DAC Circuit

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 DAC8801 due to offset modulation

versus DAC code. For best linearity performance of the DAC8801, an op amp (OPA277) as shown in Figure 18

Figure 18. Voltage Output Configuration

8