DAC8801IDGK BURR-BROWN [Burr-Brown Corporation], DAC8801IDGK Datasheet - Page 8

• Manufacturer Part Number: DAC8801IDGK
• Description: 14-Bit, Serial Input Multiplying Digital-to-Analog Converter
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

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
ladder is either switched to GND or the I
potential by the use of an external I/V converter op amp. The R-2R ladder is connected to an external reference
input V
impedance to the external reference of 5 k
to 10 V, thus providing bipolar I
resistor, output voltage ranges of -V
When using an external I/V converter and the DAC8801 R
Equation 1:
Each DAC code determines the 2R leg switch position to either GND or I
impedance as seen looking into the I
also change. Because of this, the external I/V converter op amp must have a sufficiently low offset voltage such
that the amplifier offset is not modulated by the DAC I
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
is recommended. This circuit allows V
8
V
OUT
V
+ −V
REF
REF
REF
that determines the DAC full-scale current. The R-2R ladder presents a code independent load
2R
CODE
16384
2R
2R
V
REF
2R
OUT
U1
Figure 18. Voltage Output Configuration
2R
Figure 17. Equivalent R-2R DAC Circuit
REF
current operation. By using an external I/V converter and the DAC8801 R
OUT
REF
GND
V
V
DAC8801
DD
DD
to V
terminal changes versus code, the external I/V converter noise gain will
2R
to swing from -10V to +10V.
THEORY OF OPERATION
OUT
REF
25%. The external reference voltage can vary in a range of -10 V
terminal. The I
2R
can be generated.
R
FB
I
OUT
2R
R
OUT
terminal impedance change. External op amps with
OUT
FB
2R
resistor, the DAC output voltage is given by
terminal of the DAC is held at a virtual GND
U2
_
OPA277
+
15 V
−15 V
R
2R
V+
V−
OUT
R
2R
V
O
. Because the DAC output
2R
R
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FB
GND
I
OUT
(1)
FB