AD5410ACPZ AD [Analog Devices], AD5410ACPZ Datasheet - Page 26

• Manufacturer Part Number: AD5410ACPZ
• Description: Single Channel, 16-Bit, Serial Input, Current Source DAC
• Manufacturer: AD [Analog Devices]

AD5410/AD5420
APPLICATIONS INFORMATION
DRIVING INDUCTIVE LOADS
When driving inductive or poorly defined loads connect a
0.01µF capacitor between I
stability with loads beyond 50mH. There is no maximum
capacitance limit. The capacitive component of the load may
cause slower settling, The digital Slew Rate Control feature may
also prove useful in this situation.
TRANSIENT VOLTAGE PROTECTION
The AD5410/AD5420 contains ESD protection diodes which
prevent damage from normal handling. The industrial control
environment can, however, subject I/O circuits to much higher
transients. In order to protect the AD5410/AD5420 from
excessively high voltage transients , external power diodes and a
surge current limiting resistor may be required, as shown in
Figure 39. The constraint on the resistor value is that during
normal operation the output level at IOUT must remain within
its voltage compliance limit of AV
protection diodes and resistor must have appropriate power
ratings. Further protection can be provided with Transient
Voltage Suppressors or Transorbs, these are available as both
unidirectional (protects against positive high voltage transients)
and bidirectional (protects against both positive and negative
high voltage transients) and are available in a wide range of
standoff and breakdown voltage ratings. It is recommended that
all field connected nodes are protected.
LAYOUT GUIDELINES
In any circuit where accuracy is important, careful consideration
of the power supply and ground return layout helps to ensure
the rated performance. The printed circuit board on which the
AD5410/AD5420 is mounted should be designed so that the
analog and digital sections are separated and confined to certain
areas of the board. If the AD5410/AD5420 is in a system where
multiple devices require an AGND-to-DGND connection, the
connection should be made at one point only. The star ground
point should be established as close as possible to the device.
The AD5410/AD5420 should have ample supply bypassing of
10 µF in parallel with 0.1 µF on each supply located as close to
the package as possible, ideally right up against the device. The
10 µF capacitors are the tantalum bead type. The 0.1 µF
capacitor should have low effective series resistance (ESR) and
low effective series inductance (ESI) such as the common
AD5410/
AD5420
Figure 39. Output Transient Voltage Protection
AV
AV
AGND
DD
DD
I
OUT
OUT
and GND. This will ensure
DD
R
P
– 2.5V and the two
R
LOAD
Rev. PrE | Page 26 of 30
ceramic types, which provide a low impedance path to ground
at high frequencies to handle transient currents due to internal
logic switching.
The power supply lines of the AD5410/AD5420 should use as
large a trace as possible to provide low impedance paths and
reduce the effects of glitches on the power supply line. Fast
switching signals such as clocks should be shielded with digital
ground to avoid radiating noise to other parts of the board and
should never be run near the reference inputs. A ground line
routed between the SDIN and SCLK lines helps reduce crosstalk
between them (not required on a multilayer board that has a
separate ground plane, but separating the lines helps). It is
essential to minimize noise on the REFIN line because it
couples through to the DAC output.
Avoid crossover of digital and analog signals. Traces on
opposite sides of the board should run at right angles to each
other. This reduces the effects of feed through the board. A
microstrip technique is by far the best, but not always possible
with a double-sided board. In this technique, the component
side of the board is dedicated to ground plane, while signal
traces are placed on the solder side.
GALVANICALLY ISOLATED INTERFACE
In many process control applications, it is necessary to provide
an isolation barrier between the controller and the unit being
controlled to protect and isolate the controlling circuitry from
any hazardous common-mode voltages that might occur. The
i Coupler® family of products from Analog Devices provides
voltage isolation in excess of 2.5 kV. The serial loading structure
of the AD5410/AD5420 make it ideal for isolated interfaces
because the number of interface lines is kept to a minimum.
Figure 40 shows a 4-channel isolated interface to the
AD5410/AD5420 using an ADuM1400. For further
information, visit
*ADDITIONAL PINS OMITTED FOR CLARITY
MICROPROCESSOR INTERFACING
Microprocessor interfacing to the AD5410/AD5420 is via a serial
bus that uses protocol compatible with microcontrollers and
DSP processors. The communications channel is a 3-wire
(minimum) interface consisting of a clock signal, a data signal,
Controller
Serial Clock Out
Serial Data Out
Control out
SYNC Out
ADuM1400 *
V
V
V
V
http://www.analog.com/icouplers.
IA
IB
IC
ID
Preliminary Technical Data
Figure 40. Isolated Interface
ENCODE
ENCODE
ENCODE
ENCODE
DECODE
DECODE
DECODE
DECODE
V
V
V
V
OA
OD
OB
OC
To SCLK
To SDIN
To LATCH
To CLEAR