Texas Instruments DAC8771EVM User manual

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DAC8771 Evaluation Module
User's Guide
SLAU727–August 2017
DAC8771 Evaluation Module
This user’s guide describes the characteristics and use of the DAC8771 evaluation board (EVM). It also
discusses how to setup and configure the software and hardware for proper operation. Throughout this
document, the terms evaluation board,evaluation module, and EVM are synonymous with the
DAC8771EVM.
Contents
1 Overview...................................................................................................................... 2
2 EVM Hardware Overview................................................................................................... 3
3 EVM Software Setup ........................................................................................................ 9
4 EVM Software Overview .................................................................................................. 11
5 EVM Documentation....................................................................................................... 14
List of Figures
1 DAC8771EVM Hardware Setup ........................................................................................... 3
2 DAC8771EVM Block Diagram ............................................................................................. 3
3 PVDD/AVDD, and DVDD Supply Connections.......................................................................... 5
4 Digital Communication Test Points........................................................................................ 6
5 Onboard Reference Supply Connections................................................................................. 7
6 Output Terminal Block Connections and Load Jumpers ............................................................... 7
7 SM-USB-DIG Connection................................................................................................... 8
8 DAC8771EVM Installer ..................................................................................................... 9
9 DAC8771EVM Install Path................................................................................................ 10
10 DAC8771EVM Software License Agreements ......................................................................... 10
11 EVM GUI – Front Panel ................................................................................................... 11
12 Schematic 1................................................................................................................. 14
13 Schematic 2................................................................................................................. 15
14 DAC8771EVM PCB Components Layout............................................................................... 16
List of Tables
1 Contents of DAC8771EVM Kit............................................................................................. 2
2 Related Documentation..................................................................................................... 2
3 EVM Jumper Summary ..................................................................................................... 4
4 SM-USB-DIG Connector.................................................................................................... 8
5 EVM Board Bill of Materials............................................................................................... 17

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Trademarks
Microsoft, Windows are registered trademarks of Microsoft Corporation.
1 Overview
The DAC8771 is a single-channel (quad) 16-bit precision digital-to-analog converter (DAC). The output
can be configured to produce a current in output ranges of 0 to 20 mA, 0 to 24 mA, 3.5 to 23.5 mA, or ±24
mA. It can also be configured for voltage output in ranges of 0 to 5 V, 0 to 6 V, 0 to 10 V, 0 to 12 V, ±5 V,
±6 V, ±10 V, or ±12 V. The DAC8771 includes an integrated buck-boost converter to generate all
necessary power supplies from a single external supply. The buck-boost converter features various
operating modes that can be used to enhance power dissipation and thermal performance. The DAC8771
features additional peripherals including: HART input pins for coupling of FSK HART voltage signals, slew-
rate control for the analog output, and reliability features such as CRC, watchdog timer, and conditional
alarms.
1.1 EVM Kit Contents
Table 1 details the contents of the EVM kit. Contact the nearest Texas Instruments Product Information
Center or visit the Texas Instruments E2E Community (http://E2E.ti.com) if any component is missing.
Table 1. Contents of DAC8771EVM Kit
Item # Item QTY Description or Use
1 DAC8771EVM PCB 1 EVM hardware
2 USB Extension Cable 1 Connects PC USB port to SM-USB-DIG USB connector
3 SM-USB-DIG Platform 1 Platform used for digital communication from PC to EVM
1.2 Related Documentation From Texas Instruments
The following documents provide information regarding Texas Instruments integrated circuits used in the
assembly of the DAC8771EVM. This user’s guide is available from the TI website under the literature
number SLAU727. Any letter appended to the literature number corresponds to the document revision that
is current at the time of the writing of this document. Newer revisions may be available from the TI website
at http://www.ti.com/, or by calling the Texas Instruments Literature Response Center at 1-800-477-8924
or the Product Information Center at 1-972-644-5580. When ordering identify the document by both title
and literature number.
Table 2. Related Documentation
Item # Literature Number
DAC8771 product data sheet SLASEE2
REF5050 product data sheet SBOS410
SM-USB-DIG platform user’s guide SBOU098

Copyright © 2018, Texas Instruments Incorporated
DAC8771
PVDD/AVDD
Power Supply
VOUT
IOUT
HARTIN
IEC61000-4 Protection Circuit
Placeholder
External Supplies
SM-USB-DIG
VPOS/VNEG
Internal Buck-Boost
External VREF
REF5050
Internal VREF
VREF
SPI
Copyright © 2018, Texas Instruments Incorporated
Computer SM-USB-DIG
Platform DAC8771EVM
Power Supply
USB 10-Pin Connector
Single-supply for use with buck-boost converter
Multi-supply for use without buck-boost converter
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2 EVM Hardware Overview
This section discusses the overall system setup for the EVM. A personal computer (PC) runs the software
that communicates with the SM-USB-DIG platform, which provides the power and digital signals used to
communicate with the EVM board. Connectors on the EVM board allow the user to connect the required
external power supplies for the configuration under test. The SM-USB-DIG must be connected to the
DAC8771EVM with the Texas Instruments logo facing up.
Figure 1. DAC8771EVM Hardware Setup
2.1 EVM Board Block Diagram
A block diagram of the EVM board setup is shown in Figure 2. This board provides test points for the SPI,
power, reference, ground, analog outputs, LDAC, CLR, ALARM, and RESET signals. The EVM allows the
user to select the internal buck-boost converter or external power supplies as sources for positive and
negative supply rails of each channel. The EVM also allows the user to select the internal reference,
onboard REF5050 reference, or external reference to provide the reference voltage to the DAC8771.
Figure 2. DAC8771EVM Block Diagram

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2.2 Electrostatic Discharge Warning
Many of the components on the EVM are susceptible to damage by electrostatic discharge (ESD). Users
are advised to observe proper ESD handling precautions when unpacking and handling the EVM,
including the use of a grounded wrist strap at an approved ESD workstation.
2.3 Jumper Summary
Table 3 summarizes all of the EVM jumper functionality.
Table 3. EVM Jumper Summary
Jumper Label Default Position Function
JP1 1-2 1-2 Selects positive buck-boost to supply VPOS
2-3 Selects PVDD/AVDD to supply VPOS
JP2 1-2 1-2 Selects negative buck-boost to supply VNEG
2-3 Selects EXT_VNEG to supply VNEG
JP3 Installed Installed VSENSEP is shorted to VOUT onboard
Not installed VSENSEP is shorted to VOUT off board
JP4 Installed Installed Loads VOUT/IOUT with a short to GND
Not installed Unloads VOUT/IOUT of the short to GND
JP5 Installed Installed Loads VOUT/IOUT with a 249-Ωresistor
Not installed Unloads VOUT/IOUT of the 249-Ωresistor
JP6 Not installed Installed Loads VOUT/IOUT with a 624-Ωresistor
Not installed Unloads VOUT/IOUT of the 625-Ωresistor
JP7 Not installed Installed Loads VOUT/IOUT with a 1-kΩresistor
Not installed Unloads VOUT/IOUT of the 1-kΩresistor
JP8 Installed Installed VSENSEN is shorted to GND onboard
Not installed VSENSEN is shorted to GND off board
JP9 Installed Installed When HART_IN is not in use, AC couple to GND
Not installed When HART_IN is in use, disconnect from GND
JP10 Not installed Installed Selects the external DVDD
Not installed Disconnects the external DVDD
JP11 1-2 1-2 Selects the DAC8771 internal reference
2-3 Selects the REF5050 external reference
JP12 2-3 1-2 Issues a clear command to the DAC8771
2-3 No operation
JP13 Not installed Installed Issues a hardware reset to the DAC8771
Not installed No operation
JP14 Installed Installed Select asynchronous update mode
Not installed Select asynchronous update mode
JP15 Not installed Installed Disables internal DVDD LDO
Not installed Enables internal DVDD LDO
JP16 Not installed Installed Connects the SM-USB-DIG supply to DVDD
Not installed Disconnects SM-USB-DIG supply for DVDD
JP17 Not installed Installed RSET is connected to external Resistor
Not installed Internal current setting resistor is used

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2.4 Powering the EVM
This section describes the various power configurations that can be used by the EVM.
2.4.1 PVDD/AVDD Supply
The PVDD, the buck-boost converter supply, and AVDD, the analog supply, of the DAC8771 are
connected to the same power net labeled PVDD/AVDD on the DAC8771EVM. Terminal block J3, shown
in Figure 3, allows for external voltage sources to be connected to the PVDD/AVDD supply. The
PVDD/AVDD supply must be provided regardless of whether the buck-boost converter is in use or not.
Figure 3. PVDD/AVDD, and DVDD Supply Connections
2.4.2 VPOS and VNEG Supplies
VPOS, the positive supply for the output signal chain, and VNEG, the negative supply for the output signal
chain, may be powered by the DAC8771 internal buck-boost converters or by off-board supply voltages.
WARNING
Permanent device damage may occur if externally supplying VPOS
or VNEG while the internal buck-boost supply is enabled.
When using the DAC8771 internal buck-boost converters to supply VPOS and VNEG, install JP1 and JP2
in the 1-2 position, or "inside" position, as indicated by Table 3.
When using external equipment to supply VPOS and VNEG, install JP1 and JP2 in the 2-3 position, or
"outside" position, as indicated by Table 3. In this configuration, the VPOS supply is connected to the
PVDD/AVDD net and the VNEG supply is connected to the EXT_VNEG. If bipolar supplies are used,
connect an appropriate negative supply voltage to AVSS through terminal block J4, as shown in Figure 3.
If unipolar supplies are used, connect AVSS to ground through terminal block J3.

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2.4.3 DVDD Supply
DVDD, the digital supply voltage, of the DAC8771 can be supplied by the SM-USB-DIG VDUT supply (pin
6 of J1), an external supply voltage through J5 (illustrated in Figure 3), or by the DAC8771 internal DVDD
LDO. When using the SM-USB-DIG as the DVDD supply, uninstall jumper JP10 and install jumpers JP15
and JP15. To use an external supply voltage as the DVDD supply, install jumpers JP10 and JP15 and
uninstall JP16. To use the DAC8771 internal LDO as the DVDD supply, uninstall jumpers JP10, JP15, and
JP16.
In each DVDD supply configuration, take care to ensure that digital logic thresholds of the host and
DAC8771 match and that the absolute maximum ratings of the DAC8771 are not violated.
2.5 EVM Features
This section describes some of the hardware features present on the EVM board.
2.5.1 Communication Test Points
The EVM board features test points for monitoring the communication between the SM-USB-DIG and the
DAC8771. Header J2 provide test points for the LDAC, ALARM, CLR, RESET, SDIN, SCLK, SYNC, and
SDO pins of the DAC8771.
Figure 4. Digital Communication Test Points
The EVM design also allows external signals to be connected through these communication test points if
the EVM is integrated into a custom evaluation setup or application-specific prototype. Note that if the SM-
USB-DIG platform is not used, DVDD must be configured to use the DAC8771 internal DVDD LDO or
external supplies as described in Section 2.4.3.

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2.5.2 Reference Voltage
The DAC8771 reference voltage can be supplied by the internal voltage reference, by the onboard
REF5050, or by an external reference voltage.
Figure 5. Onboard Reference Supply Connections
To use the internal reference voltage, place JP11 in the 1-2 position. To use the REF5050 reference
voltage, place JP11 in the 2-3 position and connect a supply voltage for the REF5050 to J6, as shown in
Figure 5. To use an external reference voltage, remove JP11 and the reference can be connected to the
DAC8771EVM through the center post of JP11.
2.5.3 VOUT, VSENSEP, and VSENSEN
The VOUT pins can be accessed on terminal block J7, by the OUT test points. The VSENSEP and
VSENSEN sense connections may be provided onboard or externally closer to the point of load through
terminal block J7. To provide the VSENSEP connections onboard, install JP3. Similarly, to provide the
VSENSEN connections onboard, install JP8. Removing these jumpers requires that the sense connections
are made external to the EVM board. Figure 6 shows the arrangement of the output terminal blocks.
2.5.4 IOUT
The IOUT pin can be accessed on terminal block J7 or by the test point OUT.
2.5.5 Onboard Output Loads
Four load choices are installed on the EVM board to evaluate the voltage and current outputs as well as
the adaptive power management performance of the DAC8771. JP4 is available to provide a short-circuit
condition on the output. JP5 provides a 250-Ωload on the output. JP6 provides a 625-Ωon the output.
JP7 provides a 1-kΩload on the output.
Figure 6. Output Terminal Block Connections and Load Jumpers

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2.5.6 Applying HART Signals
JP9 is available to couple external HART FSK communication signals onto the current outputs. When
injecting the HART signal, remove JP9 and apply the HART signal to JP9 pin 1. When a HART signal is
not being injected, install JP9 with AC coupling the HART pins to ground.
2.6 Connecting the SM-USB-DIG
To connect the EVM board and the SM-USB-DIG platform together, firmly slide the male and female ends
of the 10-pin connectors together with the Texas Instruments logo of the SM-USB-DIG facing up as shown
in Figure 7. Make sure that the two connectors are completely pushed together as loose connections may
cause intermittent operation.
Figure 7. SM-USB-DIG Connection
2.7 Signal Definitions of J1 (10-Pin SM-USB-DIG Connector)
Table 4 shows the pin-out for the 10-pin connector used to communicate between the EVM and the SM-
USB-DIG. Note that the I2C communication lines (I2C_SCL and I2C_SDA1) are not used.
Table 4. SM-USB-DIG Connector
Pin on J1 Signal Description
1 I2C_SCL I2C clock signal (SCL)
2 CTRL/MEAS4 GPIO: Control output or measure input
3 I2C_SDA1 I2C data signal (SDA)
4 CTRL/MEAS5 GPIO: Control output or measure input
5 SPI_DOUT1 SPI data output (MOSI)
6 VDUT Switchable DUT power supply: 3.3 V, 5 V, Hi-Z (disconnected).
Note: When VDUT is Hi-Z, all digital I/Os are Hi-Z as well
7 SPI_CLK SPI clock signal (SCLK)
8 GND Power return (GND)
9 SPI_CS1 SPI chip-select signal (!CS)
10 SPI_DIN1 SPI data input (MISO)

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3 EVM Software Setup
This section discusses how to install the EVM software.
3.1 Operating Systems for EVM Software
The EVM software has been tested on the Microsoft®Windows®XP and Windows 7 operating systems
with United States and European regional settings. The software should also function on other Windows
operating systems.
3.2 EVM Software Installation
Download the EVM software by following the instructions provided external to this document. To install the
software, locate and extract the file named DAC8771.zip to a specific folder (for example, C:\DAC8771\)
on the hard drive.
Figure 8. DAC8771EVM Installer
After the files are extracted, navigate to the folder created on the hard drive. Locate and execute the
setup.exe file to start the installation. The DAC8771 software installer file then opens to begin the
installation process.
After the installation process initializes, the user is given a choice of selecting the installation directory,
usually defaulting to C:\Program Files(x86)\DAC8771EVM\ and C:\Program Files(x86)\National
Instruments\.

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Figure 9. DAC8771EVM Install Path
After selecting the installation directory, two license agreements are presented that must be accepted.
Figure 10. DAC8771EVM Software License Agreements
After accepting the Texas Instruments and National Instruments license agreements, the progress bar
opens and shows the installation of the software. Once the installation process is completed, click Finish.