
Data Sheet
AD5410/AD5420
Rev. F | Page 29 of 32
INDUSTRIAL, HART COMPATIBLE ANALOG
OUTPUT APPLICATION
Many industrial control applications have requirements for
accurately controlled current output signals, and th
e AD5410/cifically for use in an industrial control application. The design
provides for a HART-enabled current output, with the HART
industry’s lowest power and smallest footprint HART-compliant IC
modem. For additional space-savings, th
e AD5700-1 offers a 0.5%
precision internal oscillator. The HART_OUT signal from the
AD5700 is attenuated and ac-coupled into the CAP2 pin of the
AD5420. Further information on this configuration can be found
the HART signal into the RSET pin (only applicable of the external
RSET is used), is available in Circuit Not
e CN-0270. Use of
either configuration results in th
e AD5700 HART modem output
modulating the 4 mA to 20 mA analog current without affecting
the dc level of the current. This circuit adheres to the HART
physical layer specifications as defined by the HART
Communication Foundation.
The module is powered from a field supply of 24 V. This supplies
AVDD directly. For transient overvoltage protection, transient
voltage suppressors (TVS) are placed on both the IOUT and field
supply connections. A 24 V TVS is placed on the IOUT connection,
and a 36 V TVS is placed on the field supply input. For added
protection, clamping diodes are connected from the IOUT pin to the
AVDD and GND power supply pins. The recommended external
band-pass filter for th
e AD5700 HART modem includes a 150 kΩ
resistor, which limits current to a sufficiently low level to adhere
to intrinsic safety requirements. In this case, the input has higher
transient voltage protection and should, therefore, not require
additional protection circuitry, even in the most demanding of
industrial environments.
iCoupler digital isolators; further information on iCoupler
side of the digital isolators, removing the need to generate a
digital power supply on the field side of the isolation barrier.
which is more than enough to supply the 2.8 mA requirement
frequency of up to 1 MHz. To reduce the number of isolators
required, nonessential signals such as CLEAR can be connected
to GND and FAULT, and SDO can be left unconnected, reducing
the isolation requirements to just three signals. Doing so,
however, disables the fault alert features of the part.
07027-
048
DVCC
AVDD
IOUT
DVCC
SELECT
CAP1
GND
CAP2
REFOUT REFIN
CLEAR
LATCH
SCLK
SDIN
FAULT
SDO
AD5700/AD5700-1
AD5410/AD5420
10F
0.1F
BACKP
L
ANE
I
NT
E
RF
ACE
BACKPLANE SUPPLY
IOUT
C3
0.1F
10k
1F
150pF
18
+
VDD1
VDD2
GND2
GND1
VIA
VIB
VOA
VOB
ADuM1200
VDD2
GND1
VIA
NC
GND1
VIC
VID
VIB
VOA
VOC
VOD
VOB
GND2
VE2
GND2
ADuM1400
VDD1
MICROCONTROLLER
DIGITAL
OUTPUTS
DIGITAL
INTPUTS
UART
INTERFACE
VDD2
GND1
VIA
VE1
GND1
VOC
VIB
VOA
VIC
VID
VOB
GND2
VE2
GND2
ADuM1402
VDD1
HART_OUT
TXD
RTS
RXD
CD
REF
ADC_IP
VCC
DGND
AGND
0.1F
C1
2.2nF
C2
22nF
AVDD
24V
FIELD
SUPPLY
FIELD
GROUND
SMAJ36CA
36V
150k
1.2M
300pF