Texas Instruments BOOST-DAC8730-HART, User Manual, Page: 8 / 21

BOOST-DAC8730-HART Hardware Overview
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8 SLAU699 – May 2017
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BOOST-DAC8730-HART Evaluation Module
4.3 BOOST-DAC8730-HART Power Configurations
The BOOST-DAC8730-HART provides a terminal block (J2) to connect to the external loop-supply. A
typical two-wire connection has a sense resistor tied to either the negative or positive node of the external
supply. A minimum loop resistance value of 250 ohms is commonly required for HART communication.
The minimum voltage for DAC8730 device operation and other parameter requirements are listed in the
DAC8730 data sheet (
SLASEH8 ). For correct loop operation, please be aware that the loop-supply
voltage must exceed the sum of both the minimum voltage requirement of the DAC8730 device, and the
IR drop across the sense resistor.
Table 5. BOOST-DAC8730-HART Power Supply Configuration
Connector Connection Type Description
J2 Terminal block External loop-supply connection
A loop-supply voltage of 24 V is the nominal supply voltage for most 4- to 20-mA two-wire transmitters.
4.4 SPI Communication Signals and Digital Inputs/Outputs
The SPI signals are located on the J2 header and are described in Table 6 , along with the digital input
signals of the BOOST-DAC8730-HART device.
Table 6. Digital Block Signal Definition
Name Connector Description
GND J2-1 Local GND
DS1 J2-2 Power transformer driver (driven from the REG_IN pins)
DS2 J2-3
VCCIO J2-4 External supply output
CLKOUT J2-5 Clock output
RESET J2-6 Hardware reset
CS J2-7 SPI chip select
MOSI J2-8 SPI data input
MISO J2-9 SPI data output
SCLK J2-10 SPI clock input
RX J2-11 UART RX input
TX J2-12 UART TX output
IRQ J2-13 Interrupt request output (active low)
GND J2-14 Local GND
VSHUNT J2-15 Internal DC/DC voltage FB_SUPPLY
VINL J2-16 Synchronous DAC load control input