Texas Instruments DAC8775EVM User manual

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DAC8775EVM User’s Guide
User's Guide
SBAU248–November 2016
DAC8775EVM User’s Guide
This user’s guide describes the characteristics and use of the DAC8775 evaluation board (EVM). It also
discusses how to setup and configure the software and hardware for proper operation. Throughout this
document, the terms DAC8775EVM, evaluation board, evaluation module, and EVM are synonymous with
the DAC8775EVM.
Contents
1 Overview...................................................................................................................... 2
2 EVM Hardware Overview................................................................................................... 3
3 EVM Software Setup....................................................................................................... 10
4 EVM Software Overview .................................................................................................. 12
5 EVM Documentation....................................................................................................... 15
List of Figures
1 DAC8775EVM Hardware Setup ........................................................................................... 3
2 DAC8775EVM Block Diagram ............................................................................................. 3
3 PVDD/AVDD, AVSS, and DVDD Supply Connections ................................................................. 6
4 Digital Communication Test Points........................................................................................ 7
5 Onboard Reference Supply Connections................................................................................. 8
6 Output Terminal Block Connections and Load Jumpers ............................................................... 9
7 SM-USB-DIG Connection................................................................................................... 9
8 DAC8775EVM Installer.................................................................................................... 10
9 DAC8775EVM Install Path................................................................................................ 11
10 DAC8775EVM Software License Agreements ......................................................................... 11
11 EVM GUI – Front Panel ................................................................................................... 12
12 Device Schematic.......................................................................................................... 15
13 DC-DC Schematic.......................................................................................................... 16
14 Outputs Schematic......................................................................................................... 16
15 DAC8775EVM PCB Components Layout............................................................................... 17
List of Tables
1 Contents of DAC8775EVM Kit............................................................................................. 2
2 Related Documentation..................................................................................................... 2
3 EVM Jumper Summary ..................................................................................................... 4
4 SM-USB-DIG Connector .................................................................................................. 10
5 EVM Board Bill of Materials............................................................................................... 18

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Trademarks
Windows XP, Windows 7 are registered trademarks of Microsoft.
1 Overview
The DAC8775 is a four-channel (quad) 16-bit precision digital-to-analog converter (DAC). Each 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.
Each channel 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 DAC8775 includes integrated buck-boost converters for each channel
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
DAC8775 features additional peripherals including: HART input pins for coupling of FSK HART Voltage
signals, slew-rate control for the analog outputs, 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 DAC8775EVM Kit
ITEM NO ITEM QTY DESCRIPTION OR USE
1 DAC8775EVM 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 DAC8775EVM. This user’s guide is available from the TI website under the literature
number SBAU248. 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 NO LITERATURE NUMBER
DAC8775 product data sheet SLVSBY7
REF5050 product data sheet SBOS410
SM-USB-DIG platform user’s guide SBOU098

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DAC8775
PVDD/AVDD
Power Supply
VOUTA
IOUTA
VOUTD
IOUTD
... ...
HARTINX
IEC61000-4 Protection Circuit
Placeholder
External Supplies
SM-USB-DIG
VPOSX/VNEGX
Internal Buck-Boost
External VREF
REF5050
Internal VREF
VREF
SPI
Computer SM-USB-DIG
Platform DAC8775EVM
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
DAC8775EVM with the Texas Instruments logo facing up.
Figure 1. DAC8775EVM 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 each channel’s
positive and negative supplies rails. The EVM also allows the user to select the internal reference,
onboard REF5050 reference, or external reference to provide the reference voltage to the DAC8775.
Figure 2. DAC8775EVM 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 DC/DC Channel A to supply VPOSA
2-3 Selects PVDD/AVDD to supply VPOSA
JP2 1-2 1-2 Selects DC/DC Channel A to supply VNEGA
2-3 Selects AVSS to supply VNEGA
JP3 1-2 1-2 Selects DC/DC Channel B to supply VPOSB
2-3 Selects PVDD/AVDD to supply VPOSB
JP4 1-2 1-2 Selects DC/DC Channel B to supply VNEGB
2-3 Selects AVSS to supply VNEGB
JP5 1-2 1-2 Selects DC/DC Channel C to supply VPOSC
2-3 Selects PVDD/AVDD to supply VPOSC
JP6 1-2 1-2 Selects DC/DC Channel C to supply VNEGC
2-3 Selects AVSS to supply VNEGC
JP7 1-2 1-2 Selects DC/DC Channel D to supply VPOSD
2-3 Selects PVDD/AVDD to supply VPOSD
JP8 1-2 1-2 Selects DC/DC Channel D to supply VNEGD
2-3 Selects AVSS to supply VNEGD
JP9 Not installed Installed Connects the SM-USB-DIG supply to DVDD
Not installed Disconnects the SM-USB-DIG supply from DVDD
JP10 1-2 1-2 Selects the DAC8775 internal reference
2-3 Selects the REF5050 external reference
JP11 Not installed Installed Disables internal DVDD LDO
Not installed Enables internal DVDD LDO
JP12 2-3 1-2 Issues a clear command to the DAC8775
2-3 No operation
JP13 Not installed Installed Selects the external DVDD
Not installed Disconnects the external DVDD
JP14 Not installed Installed Issues a hardware reset to the DAC8775
Not installed No operation
JP15 Installed Installed Select asynchronous update mode
Not installed Select synchronous update mode
JP16 Installed Installed VSENSEPA is shorted to VOUTA on-board
Not installed VSENSEPA is shorted to VOUTA off-board
JP17 Installed Installed VSENSEPB is shorted to VOUTB onboard
Not installed VSENSEPB is shorted to VOUTB off-board
JP18 Not installed Installed Loads VOUTA/IOUTA with a short to GND
Not installed Unloads VOUTA/IOUTA of the short to GND
JP19 Installed Installed Loads VOUTA/IOUTA with a 250-Ωresistor
Not installed Unloads VOUTA/IOUTA of the 250-Ωresistor
JP20 Not installed Installed Loads VOUTA/IOUTA with a 625-Ωresistor
Not installed Unloads VOUTA/IOUTA of the 625-Ωresistor

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Table 3. EVM Jumper Summary (continued)
JUMPER LABEL DEFAULT POSITION FUNCTION
JP21 Not installed Installed Loads VOUTA/IOUTA with a 1-kΩresistor
Not installed Unloads VOUTA/IOUTA the 1-kΩresistor
JP22 Not installed Installed Loads VOUTB/IOUTB with a short to GND
Not installed Unloads VOUTB/IOUTB of the short to GND
JP23 Not installed Installed Loads VOUTB/IOUTB with a 250-Ωresistor
Not installed Unloads VOUTB/IOUTB of the 250-Ωresistor
JP24 Not installed Installed Loads VOUTB/IOUTB with a 625-Ωresistor
Not installed Unloads VOUTB/IOUTB of the 625-Ωresistor
JP25 Not installed Installed Loads VOUTB/IOUTB with a 1-kΩresistor
Not installed Unloads VOUTB/IOUTB the 1-kΩresistor
JP26 Installed Installed VSENSENA is shorted to GND onboard
Not installed VSENSENA is shorted to GND off-board
JP27 Installed Installed VSENSENB is shorted to GND onboard
Not installed VSENSENB is shorted to GND off-board
JP28 Installed Installed When HARTIN_A is not in use, AC couple to GND
Not installed When HARTIN_A is in use, disconnect from GND
JP29 Installed Installed When HARTIN_B is not in use, AC couple to GND
Not installed When HARTIN_B is in use, disconnect from GND
JP30 Installed Installed VSENSEPC is shorted to VOUTA onboard
Not installed VSENSEPC is shorted to VOUTA off-board
JP31 Installed Installed VSENSEPD is shorted to VOUTB onboard
Not installed VSENSEPD is shorted to VOUTB off-board
JP32 Not installed Installed Loads VOUTC/IOUTC with a short to GND
Not installed Unloads VOUTC/IOUTC of the short to GND
JP33 Not installed Installed Loads VOUTC/IOUTC with a 250-Ωresistor
Not installed Unloads VOUTC/IOUTC of the 250-Ωresistor
JP34 Not installed Installed Loads VOUTC/IOUTC with a 625-Ωresistor
Not installed Unloads VOUTC/IOUTC of the 625-Ωresistor
JP35 Not installed Installed Loads VOUTC/IOUTC with a 1-kΩresistor
Not installed Unloads VOUTC/IOUTC the 1-kΩresistor
JP36 Not installed Installed Loads VOUTD/IOUTD with a short to GND
Not installed Unloads VOUTD/IOUTD of the short to GND
JP37 Not installed Installed Loads VOUTD/IOUTD with a 250-Ωresistor
Not installed Unloads VOUTD/IOUTD of the 250-Ωresistor
JP38 Not installed Installed Loads VOUTD/IOUTD with a 625-Ωresistor
Not installed Unloads VOUTD/IOUTD of the 625-Ωresistor
JP39 Not installed Installed Loads VOUTD/IOUTD with a 1-kΩresistor
Not installed Unloads VOUTD/IOUTD the 1-kΩresistor
JP40 Installed Installed VSENSENC is shorted to GND onboard
Not installed VSENSENC is shorted to GND off-board
JP41 Installed Installed VSENSEND is shorted to GND onboard
Not installed VSENSEND is shorted to GND off-board
JP42 Installed Installed When HARTIN_C is not in use, AC couple to GND
Not installed When HARTIN_C is in use, disconnect from GND
JP43 Installed Installed When HARTIN_D is not in use, AC couple to GND
Not installed When HARTIN_D is in use, disconnect from GND

PVDD/AVDD
GND
AVSS
GND
GND
DVDD
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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_X/AVDD Supply
The PVDD_X, the buck-boost converter supplies, and AVDD, the analog supply, of the DAC8775 are
connected to the same power net labeled PVDD/AVDD on the DAC8775EVM. Terminal block J2, 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, AVSS, and DVDD Supply Connections
2.4.2 VPOS_X and VNEG_X Supplies
VPOS_X, the positive supply for the output signal chain, and VNEG_X, the negative supply for the output
signal chain, may be powered by the DAC8775 internal buck-boost converters or by off-board supply
voltages.
WARNING
Permanent device damage may occur if externally supplying
VPOS_X or VNEG_X while the internal buck-boost supply is
enabled.
When using the DAC8775 internal buck-boost converters to supply VPOS_X and VNEG_X, install JP1
through JP8 (or the two jumpers that correspond to the channel of interest) in the 1-2 position, or "inside"
position, as indicated by Table 3.
When using external equipment to supply VPOS_X and VNEG_X, install JP1 through JP8 (or the two
jumpers that correspond to the channel of interest) in the 2-3 position, or "outside" position, as indicated
by Table 3. In this configuration, the VPOS_X supplies are connected to the PVDD/AVDD net and the
VNEG_X supplies are connected to the AVSS net. If bipolar supplies are used, connect an appropriate
negative supply voltage to AVSS through terminal block J3, 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 DAC8775 can be supplied by the SM-USB-DIG VDUT supply (pin
6 of J1), an external supply voltage through J4 (illustrated in Figure 3), or by the DAC8775 internal DVDD
LDO. When using the SM-USB-DIG as the DVDD supply, uninstall jumper JP13 and install jumpers JP9
and JP11. To use an external supply voltage as the DVDD supply, install jumpers JP13 and JP11 and
uninstall JP9. To use the DAC8775 internal LDO as the DVDD supply, uninstall jumpers JP9, JP13, and
JP11.
In each DVDD supply configuration, take care to ensure that digital logic thresholds of the host and
DAC8775 match and that the absolute maximum ratings of the DAC8775 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
DAC8775. Test points are provided for the !LDAC, CLR, ALARM, RESET, SDIN, SCLK, !SYNC, and SDO
pins of the DAC8775.
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 DAC8775 internal DVDD LDO or
external supplies as described in Section 2.4.3.

+5V
GND
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2.5.2 Reference Voltage
The DAC8775 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 JP10 in the 1-2 position. To use the REF5050 reference
voltage, place JP10 in the 2-3 position and connect a supply voltage for the REF5050 to J9, as shown in
Figure 5. To use an external reference voltage, remove JP10 and the reference can be connected to the
DAC8775EVM through the center post of JP10.
2.5.3 VOUT_X, VSENSEP_X, and VSENSEN_X
The VOUT_X pins can be access on terminal blocks J5, J6, J7, and J8 or by the OUT_A, OUT_B,
OUT_C, or OUT_D test points. The VSENSEP_X and VSENSEN_X sense connections may be provided
onboard or externally closer to the point of load through terminal blocks J5, J6, J7, or J8. To provide the
VSENSEP_X connections onboard, install JP16, JP17, JP30, or JP31 based on the channel of interest.
Similarly, to provide VSENSEN_X connections onboard, install JP26, JP27, JP40, or JP41. 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_X
The IOUT_X pins can be accessed on terminal blocks J5, J6, J7, or J8 or by the test points OUT_A,
OUT_B, OUT_C, or OUT_D.
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 DAC8775. JP18, JP22, JP32, or JP36 are available
to provide a short-circuit condition on the outputs. JP19, JP23, JP33, or JP37 provide a 250-Ωload on the
outputs. JP20, JP24, JP34, or JP38 are available to provide a 625-Ωon the outputs. JP21, JP25, JP35, or
JP39 provides a 1-kΩload on the outputs.

Load
Jumpers
GND
VSENSEN_A
VOUT/IOUT_A
VSENSEP_A
GND
VSENSEN_B
VOUT/IOUT_B
VSENSEP_B
GND
VSENSEN_C
VOUT/IOUT_C
VSENSEP_C
GND
VSENSEN_D
VOUT/IOUT_D
VSENSEP_D
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Figure 6. Output Terminal Block Connections and Load Jumpers
2.5.6 Applying HART Signals
JP28, JP29, JP42, and JP43 are available to couple external HART FSK communication signals onto the
current outputs. When injecting the HART signal, remove JP28, JP29, JP42, or JP43 and apply the HART
signal to pin 1. When a HART signal is not being injected, install JP28, JP29, JP42, or JP43, 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

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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)
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 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
The EVM software may be downloaded by following the instructions provided external to this document.
To install the software, locate and extract the file named DAC8775.zip to a specific folder (for example,
C:\DAC8775\) on the hard drive.
Figure 8. DAC8775EVM Installer