DAC8750IPWPR datasheet(37/53 Pages) TI1

37 / 53 page

IOUT

15V

RSET

GND

AVDD

VREFIN/VREFOUT

GND

DIN

SCLK

LDAC

15V

-15V

15V

-15V

DAC7750, DAC8750

www.ti.com

SBAS538B – DECEMBER 2013 – REVISED JUNE 2016

Product Folder Links: DAC7750 DAC8750

Submit Documentation Feedback

Typical Application (continued)

Figure 63. Generic Design for Typical PLC Current and Voltage Outputs

The current output circuit is comprised of amplifiers A1 and A2, MOSFETs Q1 and Q1, and the three resistors

RSET, RA, and RB. This two-stage current source enables the ground-referenced DAC output voltage to drive the

high-side amplifier required for the current-source.

The high-level of integration of the DACx750 family lends itself very well to the design of analog output modules,

offering simplicity of design and reducing solution size. The DACx750 integrates all of the components shown in

Figure 63 allowing a software configurable current output driver. Figure 62 illustrates an example circuit design

for such an application using the DACx750 for the current output driver.

The design uses two triple channel isolators (ISO7631FC) to provide galvanic isolation for the digital lines to

communicate to the main controller. Note that these isolators can be driven by the internally-generated supply

(DVDD) from the DACx750 to save components and cost. The DACx750 supplies up to 10 mA that meets the

supply requirements of the two isolators running at up to 10 Mbps. Note that additional cost savings are possible

if noncritical digital signals such as CLR and ALARM are tied to GND or left unconnected. Finally, a protection

scheme with transient voltage suppressors and other components is placed on all pins which connect to the field.

The protection circuitry is designed to provide immunity to the IEC61000-4 test suite which includes system-level

industrial transient tests. The protection circuit includes transient voltage suppressor (TVS) diodes, clamp-to-rail

steering diodes, and pass elements in the form of resistors and ferrite beads. For more detail about selecting

these components, refer to Single-Channel Industrial Voltage & Current Output Driver, Isolated, EMC/EMI Tested

Reference Design.

9.2.1.3 Application Curve

The current output circuit was measured in 0-mA to 24-mA mode using an 8.5 digit digital multi-meter to measure

the output while driving a 300-

Ω load at 25°C. The measured results are shown in Figure 64. The current output

remains within the data sheet specified performance.

The design was also exposed to IEC61000-4 electrostatic discharge, electrically fast transient, conducted

immunity, and radiated immunity tests on both the current and voltage outputs. During each of these tests a 6.5

digit digital multi-meter, set in fast 5.5 digit acquisition mode, was used to monitor the output. Complete data sets

for the voltage and current outputs during these tests are available in Single-Channel Industrial Voltage &

Current Output Driver, Isolated, EMC/EMI Tested Reference Design.

DAC8750IPWPR Datasheet(PDF) 37 Page - Texas Instruments

DAC8750IPWPR Datasheet(HTML) 37 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

Datasheet Download

Link URL