AD5024 Analog Devices, AD5024 Datasheet - Page 26

• Manufacturer Part Number: AD5024
• Manufacturer: Analog Devices

Specifications of AD5024

• Resolution (bits): 12bit
• Dac Update Rate: 125kSPS
• Dac Settling Time: 8µs
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

AD5024/AD5044/AD5064
APPLICATIONS INFORMATION
USING A REFERENCE AS A POWER SUPPLY
Because the supply current required by the AD5024/AD5044/
AD5064/AD5064-1 is extremely low, an alternative option is to
use a voltage reference to supply the required voltage to the parts
(see Figure 56). This is especially useful if the power supply is
quite noisy or if the system supply voltages are at some value
other than 5 V (for example, 15 V). The voltage reference outputs
a steady supply voltage for the AD5024/AD5044/AD5064/
AD5064-1. If the low dropout
3 mA of current to the AD5024/AD5044/AD5064/AD5064-1,
with no load on the output of the DAC. When the DAC output is
loaded, the REF195 also needs to supply the current to the load.
The total current required (with a 5 kΩ load on the DAC output) is
The load regulation of the REF195 is typically 2 ppm/mA,
which results in a 3 ppm (15 μV) error for the 4 mA current
drawn from it. This corresponds to a 0.196 LSB error.
BIPOLAR OPERATION
The AD5024/AD5044/AD5064/AD5064-1 have been designed
for single-supply operation, but a bipolar output range is also
possible using the circuit shown in Figure 57. The circuit gives an
output voltage range of ±5 V. Rail-to-rail operation at the
amplifier output is achievable using an
as the output amplifier.
Assuming V
be calculated as follows:
where D represents the input code in decimal (0 to 65,535).
With V
Figure 56. REF195 as Power Supply to the AD5024/AD5044/AD5064/AD5064-1
INTERFACE
3 mA + (5 V/5 kΩ) = 4 mA
V
V
OUT
OUT
SERIAL
3-WIRE
DD
= 5 V, R1 = R2 = 10 kΩ,
=
=
DD
⎛
⎜
⎝
⎡
⎢
⎣
V
10
65
= V
DD
SYNC
SCLK
,
×
536
DIN
×
D
REF
15V
⎛
⎜
⎝
⎞
⎟
⎠
, the output voltage for any input code can
65
REF195
−
D
,
536
5
V
⎞
⎟
⎠
×
REF195
⎛
⎜
⎝
R1
5V
AD5064-1
AD5024/
AD5044/
AD5064/
R1
+
V
R2
is used, it must supply
DD
AD8638
⎞
⎟
⎠
−
V
DD
or an
V
×
OUT
⎛
⎜
⎝
R2
R1
= 0V TO 5V
AD8639
⎞
⎟
⎠
⎤
⎥
⎦
Rev. E | Page 26 of 28
This is an output voltage range of ±5 V, with 0x0000 corre-
sponding to a −5 V output, and 0xFFFF corresponding to a
+5 V output.
USING THE AD5024/AD5044/AD5064/AD5064-1
WITH A GALVANICALLY ISOLATED INTERFACE
In process control applications in industrial environments, it
is often necessary to use a galvanically isolated interface to
protect and isolate the controlling circuitry from any hazardous
common-mode voltages that can occur in the area where the
DAC is functioning. iCoupler® provides isolation in excess of
2.5 kV. The AD5024/AD5044/AD5064/AD5064-1 use a 3-wire
serial logic interface, so the ADuM1300 three-channel digital
isolator provides the required isolation (see Figure 58). The
power supply to the part also needs to be isolated, which is done
by using a transformer. On the DAC side of the transformer, a
5 V regulator provides the 5 V supply required for the AD5024/
AD5044/AD5064/AD5064-1.
Figure 58. AD5024/AD5044/AD5064/AD5064-1 with a Galvanically Isolated
+5V
DATA
POWER
SCLK
SDI
10µF
V
V
V
V
REF
IA
IB
IC
ADuM1300
5V
0.1µF
Figure 57. Bipolar Operation
V
V
V
OA
OB
OC
SERIAL INTERFACE
V
V
REFA
DD
AD5064-1
AD5024/
AD5044/
AD5064/
R1 = 10kΩ
Interface
3-WIRE
REGULATOR
SYNC
DIN
SCLK
V
5V
OUTA
AD5064-1
AD5024/
AD5044/
AD5064/
GND
V
DD
AD8638/
AD8639
R2 = 10kΩ
+5V
–5V
V
OUT
10µF
x
0.1µF
±5V