AD5412ACPZ AD [Analog Devices], AD5412ACPZ Datasheet - Page 33

• Manufacturer Part Number: AD5412ACPZ
• Description: Single Channel, 12/16-Bit, Serial Input, Current Source & Voltage Output DAC
• Manufacturer: AD [Analog Devices]

Preliminary Technical Data
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 AD5412/AD5422 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 AD5412/AD5422 from
excessively high voltage transients , external power diodes and a
surge current limiting resistor is required, as shown in Figure
64. 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
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.
SINGLE CONNECTOR FOR I
Typically in analog output modules that facilitate both current
and voltage outputs there is a seperate connector for each
current output and for each voltage output even though either
the voltage output or the current output can be used at any one
time, this results in a redundant connector. For instance in an 8
channel current and voltage output module there will be 16
connectors and only 8 of these will be in use at any one time
resulting in 8 redundant connectors. The AD5412/AD5422 can
be configured with the I
and to one connector, thus removing the redundant connector
and allowing for a reduced sized connector block. Figure 65
shows that with an external buffer amplifier the
AD5412/AD5422 can be configured with a single output
connector for current and voltage output.
AD5412/
AD5422
Figure 64. Output Transient Voltage Protection
AV
AV
AGND
DD
DD
I
OUT
OUT
OUT
and V
and GND. This will ensure
DD
– 2.5V and the two protection
OUT
R
OUT
P
pins connected together
AND V
OUT
R
LOAD
Rev. PrF | Page 33 of 38
When the AD5412/AD5422 is configured for a voltage output
the I
output the V
buffer is to prevent current leakage to ground through the
+V
is internally connected to AGND through a resistance of
approx. 40kΩ.
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 AD5412/AD5422 make it ideal for isolated interfaces
because the number of interface lines is kept to a minimum.
Figure 66 shows a 4-channel isolated interface to the
AD5412/AD5422 using an ADuM1400. For further
information, visit
*ADDITIONAL PINS OMITTED FOR CLARITY
MICROPROCESSOR INTERFACING
Microprocessor interfacing to the AD5412/AD5422 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,
and a latch signal. The AD5412/AD5422 require a 24-bit data-
word with data valid on the rising edge of SCLK.
Controller
Serial Clock Out
Serial Data Out
SENSE
Control out
OUT
SYNC Out
pin when the current output is enabled, the +V
pin will be in tri-state, when configured for a current
AD5412/
AD5422
Figure 65. Connecting I
OUT
+V
pin will be in tri-state, the function of the
-V
ADuM1400 *
V
V
V
V
http://www.analog.com/icouplers.
IA
IB
IC
ID
V
SENSE
SENSE
I
OUT
OUT
Figure 66. Isolated Interface
ENCODE
ENCODE
ENCODE
ENCODE
OUT
and V
OUT
DECODE
DECODE
DECODE
DECODE
AD5412/AD5422
to one connector
I
V
V
V
V
OUT
OA
OD
OB
OC
/ V
OUT
SENSE
To SCLK
To SDIN
To LATCH
To CLEAR
pin