11

®

DAC7631

TYPICAL PERFORMANCE CURVES: VSS = –5V (Cont.)

At TA = +25°C, VDD = VCC = +5V, VSS = –5V, VREFH = +2.5V, and VREFL = –2.5V, representative unit, unless otherwise specified.

Time (2

µs/div)

OUTPUT VOLTAGE vs SETTLING TIME

(+2.5V to –2.5V)

Large-Signal Settling Time: 1V/div

Small-Signal Settling Time:

2LSB/div

+5V

LDAC

0

THEORY OF OPERATION

The DAC7631 is a 16-bit voltage-output Digital-to-Analog

Converter (DAC). The architecture is an R-2R ladder con-

figuration with the three MSB’s segmented, followed by an

operational amplifier that serves as a buffer, as shown in

Figure 1. The minimum voltage output (zero-scale) and

maximum voltage output (full-scale) are set by external

voltage references at VREFL and VREFH, respectively.

The digital input is a 16-bit serial word representing the

16-bit DAC input code, sent MSB first. The DAC7631 can

be powered from either a single +5V supply or a dual

±5V

supply. The device offers a reset function which immedi-

ately sets the output voltage and DAC register to mid-scale

code (8000H) or to zero-scale code (0000H). See Figures 2

and 3 for the basic operation of the DAC7631.

R

2R

2R

2R

2R

2R

2R

2R

2R

2R

V

REFH

V

OUT

V

OUT Sense

V

REFH Sense

V

REFL

V

REFL Sense

R

F

FIGURE 1. DAC7631 Architecture.