AD5662BRM-1 Analog Devices Inc, AD5662BRM-1 Datasheet - Page 20

• Manufacturer Part Number: AD5662BRM-1
• Description: IC,D/A CONVERTER,SINGLE,16-BIT,CMOS,TSSOP,8PIN
• Manufacturer: Analog Devices Inc
• Series: nanoDAC™r

Specifications of AD5662BRM-1

• Design Resources: 4 mA to 20 mA Process Control Loop Using AD5662 (CN0009) 16-Bit Fully Isolated Voltage Output Module Using AD5662, ADuM1401, and External Amplifiers (CN0063) 16-Bit Fully Isolated 4 mA to 20 mA Output Module Using AD5662, ADuM1401, and External Amplifiers (CN0064)
• Settling Time: 8µs
• Number Of Bits: 16
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 750µW
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD5662
USING AD5662 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 might occur in the area where the
DAC is functioning. Isocouplers provide isolation in excess of
3 kV. The AD5662 uses a 3-wire serial logic interface, so the
ADuM130x 3-channel digital isolator provides the required
isolation (see Figure 44). 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 AD5662.
DATA
SCLK
SDI
POWER
Figure 44. AD5662 with a Galvanically Isolated Interface
V1A
V1B
V1C
ADMu103x
VOB
VOC
REGULATOR
+5V
SCLK
SYNC
DIN
AD5662
GND
V
DD
V
10μF
OUT
0.1μF
Rev. A | Page 20 of 24
POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in a circuit, it is helpful to carefully
consider the power supply and ground return layout on the
board. The printed circuit board containing the AD5662 should
have separate analog and digital sections, each having its own
area of the board. If the AD5662 is in a system where other
devices require an AGND-to-DGND connection, the connection
should be made at one point only. This ground point should be
as close as possible to the AD5662.
The power supply to the AD5662 should be bypassed with 10 μF
and 0.1 μF capacitors. The capacitors should be located as close
as possible to the device, with the 0.1 μF capacitor ideally right
up against the device. The 10 μF capacitors are the tantalum
bead type. It is important that the 0.1 μF capacitor has low
effective series resistance (ESR) and effective series inductance
(ESI), for example, common ceramic types of capacitors. This
0.1 μF capacitor provides a low impedance path to ground for
high frequencies caused by transient currents due to internal
logic switching.
The power supply line itself should have as large a trace as
possible to provide a low impedance path and to reduce glitch
effects on the supply line. Clocks and other fast switching
digital signals should be shielded from other parts of the board
by digital ground. Avoid crossover of digital and analog signals
if possible. When traces cross on opposite sides of the board,
ensure that they run at right angles to each other to reduce
feedthrough effects through the board. The best board layout
technique is the microstrip technique where the component
side of the board is dedicated to the ground plane only and the
signal traces are placed on the solder side. However, this is not
always possible with a 2-layer board.