AD5737 Analog Devices, AD5737 Datasheet - Page 40

• Manufacturer Part Number: AD5737
• Description: Quad Channel, 12-Bit, Serial Input, 4-20mA Output DAC with Dynamic Power Control and HART Connectivity
• Manufacturer: Analog Devices

Specifications of AD5737

• Resolution (bits): 12bit
• Dac Settling Time: 15µs
• Max Pos Supply (v): +33V
• Single-supply: No
• Dac Type: Current Out
• Dac Input Format: Ser,SPI

AD5737
TRANSIENT VOLTAGE PROTECTION
The
age from normal handling. The industrial control environment
can, however, subject I/O circuits to much higher transients. To
protect the
external power diodes and a surge current limiting resistor (R
are required, as shown in Figure 62. A typical value for R
The two protection diodes and the resistor (R
priate power ratings.
Further protection can be provided using transient voltage
suppressors (TVSs), also referred to as transorbs. These compo-
nents are available as unidirectional suppressors, which protect
against positive high voltage transients, and as bidirectional
suppressors, which protect against both positive and negative
high voltage transients. Transient voltage suppressors are avail-
able in a wide range of standoff and breakdown voltage ratings.
The TVS should be sized with the lowest breakdown voltage
possible while not conducting in the functional range of the
current output.
It is recommended that all field connected nodes be protected.
MICROPROCESSOR INTERFACING
Microprocessor interfacing to the
that uses a protocol compatible with microcontrollers and DSP
processors. The communication channel is a 3-wire minimum
interface consisting of a clock signal, a data signal, and a latch
signal. The
on the falling edge of SCLK.
The DAC output update is initiated either on the rising edge of
LDAC or, if LDAC is held low, on the rising edge of SYNC . The
contents of the registers can be read using the readback function.
CONVERTER)
DC-TO-DC
AD5737
(FROM
C
4.7µF
DCDC
AD5737
AD5737
Figure 62. Output Transient Voltage Protection
contains ESD protection diodes that prevent dam-
R
FILTER
10Ω
from excessively high voltage transients,
requires a 24-bit data-word with data valid
C
0.1µF
FILTER
AD5737
V
BOOST_x
AGND
I
OUT_x
AD5737
D1
D2
is via a serial bus
R
P
P
) must have appro-
R
P
LOAD
is 10 Ω.
Rev. A | Page 40 of 44
P
)
AD5737-to-ADSP-BF527 Interface
The
of the ADSP-BF527, an Analog Devices, Inc., Blackfin® DSP.
Figure 63 shows how the SPORT interface can be connected
to control the AD5737.
LAYOUT GUIDELINES
Grounding
In any circuit where accuracy is important, careful consider-
ation of the power supply and ground return layout helps to
ensure the rated performance. The printed circuit board on
which the
analog and digital sections are separated and confined to
certain areas of the board. If the
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 GNDSW
supply are referred to as PGND. PGND should be confined to
certain areas of the board, and the PGND-to-AGND connection
should be made at one point only.
Supply Decoupling
The
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 cap-
acitors should have low effective series resistance (ESR) and low
effective series inductance (ESL), such as the common ceramic
types, which provide a low impedance path to ground at high
frequencies to handle transient currents due to internal logic
switching.
AD5737
AD5737
ADSP-BF527
AD5737
Figure 63. AD5737-to-ADSP-BF527 SPORT Interface
can be connected directly to the SPORT interface
should have ample supply bypassing of 10 μF
x
SPORT_TSCLK
pin and the ground connection for the AV
SPORT_TFS
SPORT_DT0
is mounted should be designed so that the
GPIO0
AD5737
SYNC
SCLK
SDIN
LDAC
is in a system where
AD5737
Data Sheet
CC