Datasheet
200 mA )
5 V
5 kW
+ 1.2 mA
V
O
+ ƪ
ǒ
V
REF
2
) V
REF
D
65536
Ǔ
ǒ
R
1
) R
2
R
1
Ǔ
* V
REF
ǒ
R
2
R
1
Ǔ
ƫ
REF02
Three-Wire
Serial
Interface
+5V
285 Am
V =0Vto5V
OUT
SYNC
SCLK
D
IN
+15V
DAC8550
V
O
+ 10
D
65536
V
FB
V
REF
V
REF
+6V
5V
-6V
OPA703
DAC8550
10 Fm 0.1 Fm
R
1
10kW
R
2
10kW
Three-Wire
SerialInterface
V
OUT
DAC8550
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SLAS476E –MARCH 2006–REVISED MARCH 2012
APPLICATION INFORMATION
(2)
USING THE REF02 AS A POWER SUPPLY
FOR THE DAC8550
The load regulation of the REF02 is typically
0.005%/mA, resulting in an error of 299μV for the
Due to the extremely low supply current required by
1.2mA current drawn from it. This value corresponds
the DAC8550, an alternative option is to use a REF02
to an 8.9LSB error.
+5V precision voltage reference to supply the
required voltage to the device, as shown in Figure 53.
BIPOLAR OPERATION USING THE DAC8550
The DAC8550 has been designed for single-supply
operation, but a bipolar output range is also possible
using the circuit in Figure 54. The circuit shown gives
an output voltage range of ±V
REF
. Rail-to-rail
operation at the amplifier output is achievable using
an OPA703 as the output amplifier.
The output voltage for any input code can be
calculated as follows:
(3)
where D represents the input code in 2's complement
(–32768 to +32767).
With V
REF
= 5V, R
1
= R
2
= 10kΩ.
Figure 53. REF02 as a Power Supply to the
DAC8550
(4)
This configuration is especially useful if the power
Using this example, an output voltage range of ±5V
supply is quite noisy or if the system supply voltages
with 8000h corresponding to a –5V output and 8FFFh
are at some value other than 5V. The REF02 outputs
corresponding to a 5V output can be achieved.
a steady supply voltage for the DAC8550. If the
Similarly, using V
REF
= 2.5V, a ±2.5V output voltage
REF02 is used, the current it needs to supply to the
range can be achieved.
DAC8550 is 250μA. This configuration is with no load
on the output of the DAC. When a DAC output is
loaded, the REF02 also needs to supply the current
to the load. The total typical current required (with a
5kΩ load on the DAC output) is:
Figure 54. Bipolar Output Range
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