Datasheet
11
®
DAC7641
Time (2µs/div)
OUTPUT VOLTAGE vs SETTLING TIME
(+2.5V to –2.5V)
Output Voltage
Large-Signal Settling Time: 1V/div
Small-Signal Settling Time:
2LSB/div
+5V
LDAC
0
TYPICAL PERFORMANCE CURVES: V
SS
= –5V (Cont.)
At T
A
= +25°C, V
DD
= +5V, V
SS
= –5V, V
REFH
= +2.5V, V
REFL
= –2.5V, representative unit, unless otherwise specified.
THEORY OF OPERATION
The DAC7641 is a voltage output, 16-bit digital-to-analog
converter (DAC). The architecture is an R-2R ladder con-
figuration with the three MSBs segmented, followed by an
operational amplifier that serves as a buffer (see Figure 1).
The minimum voltage output (zero-scale) and maximum
voltage output (full-scale) are set by the external voltage
references V
REF
L and V
REF
H, respectively. The digital input
is a 16-bit parallel word and the DAC input register offers a
readback capability. The converters can be powered from
either a single +5V supply or a dual ±5V supply. The device
offers a reset function which immediately sets all DAC
output voltages and DAC registers to mid-scale code 8000
H
or to zero-scale code 0000
H
. See Figures 2 and 3 for the
basic operation of the DAC7641.
R
2R
R
F
2R2R 2R 2R 2R 2R 2R 2R
V
REF
H
V
OUT
V
OUT
Sense
V
REF
H Sense
V
REF
L
V
REF
L Sense
FIGURE 1. DAC7641 Architecture.