ad5066bruz-1reel7 Analog Devices, Inc., ad5066bruz-1reel7 Datasheet - Page 19

• Manufacturer Part Number: ad5066bruz-1reel7
• Description: Fully Accurate 16-bit Unbuffered Vout Dac Spi Interface 2.7 V To 5.5 V In A Tssop
• Manufacturer: Analog Devices, Inc.

Preliminary Technical Data
THREE-WIRE
APPLICATIONS
USING A REFERENCE AS A POWER SUPPLY FOR
THE AD5066
Because the supply current required by the AD5066 is extremely
low, an alternative option is to use a voltage reference to supply
the required voltage to the parts (see Figure 14). 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 or 3 V,
for example, 15 V. The voltage reference outputs a steady supply
voltage for the AD5066. If the low dropout
must supply 500 µA of current to the AD5066, 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 1.5 mA current
drawn from it. This corresponds to a 0.196 LSB error.
BIPOLAR OPERATION USING THE AD5066
The AD5066 has been designed for single-supply operation,
but a bipolar output range is also possible using the circuit in
Figure 15. The circuit gives an output voltage range of ±5 V.
Rail-to-rail operation at the amplifier output is achievable using
an
The output voltage for any input code can be calculated as
follows:
where D represents the input code in decimal (0 to 65,535).
With V
This is an output voltage range of ±5 V, with 0x0000 corre-
sponding to a −5 V output, and 0xFFFF corresponding to a
INTERFACE
AD820
500 µA + (5 V/5 kΩ) = 1.5 mA
SERIAL
V
V
O
O
DD
Figure 14. REF195 as Power Supply to the AD5025/45/65
= 5 V, R1 = R2 = 10 kΩ,
ª
«
¬
§
¨
©
or an
V
10
65
DD
,
u D
536
SYNC
SCLK
u
OP295
DIN
§
¨
©
15V
·
¸
¹
65

D
,
536
REF195
5
as the output amplifier.
V
·
¸
¹
u
§
¨
©
R1
R1
5V

AD 5066
R2
V
·
¸
¹
DD

V
REF195
DD
u
V
§
¨
©
OUT
R2
R1
is used, it
·
¸
¹
= 0V TO 5V
º
»
¼
Rev. PrB | Page 19 of 20
+5 V output.
+5V
USING THE AD5066 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. i Coupler® provides isolation in excess
of 2.5 kV. The AD5066 uses a 3-wire serial logic interface, so the
ADuM1300 three-channel digital isolator provides the required
isolation (see Figure 16). 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 AD5066.
DATA
SCLK
SDI
POWER
Figure 16. AD5025/45/65 with a Galvanically Isolated Interface
10µF
V
V
V
IA
IB
IC
Figure 15. Bipolar Operation with the AD5066
ADuM1300
0.1µF
V
V
V
OA
OB
OC
V
THREE-WIRE
DD
AD5066
INTERFACE
R1 = 10kŸ
SERIAL
REGULATOR
V
5V
SCLK
SYNC
DIN
OUT
AD5066
GND
V
DD
AD820/
OP295
R2 = 10kŸ
+5V
–5V
V
10µF
OUT
AD5066
0.1µF
±5V