Applications Information

Full-Scale Output Voltage Range Selection

The DAC0890 has been designed for ease of use All refer-

ence voltage and output amplifier connections are internal

All trims such as full-scale (gain) and zero (offset) are per-

formed during manufacturing Therefore no external trim-

ming is required to achieve the specified accuracy The only

external connections required select the desired full-scale

output voltage range

The two full-scale output voltage ranges are selected by

connecting SENSE SELECT and VOUT as shown in

Figure

2a b The 255V range can be used with supply voltages as

low as 475V The 102V range can be selected with sup-

plies as low as 120V

TLH10592 – 8

FIGURE 2a 0V to 255V Output Voltage Range

TLH10592 – 9

FIGURE 2b 0V to 102V Output Voltage Range

Power Supply Voltage

The DAC0890 is designed to operate on a single power

operation the power supply voltage can be as low as

a

475V When the 102V full-scale is used the supply volt-

Grounding and Power Supply

Bypassing

Proper grounding is essential to extract all the precision and

full rated performance that the DAC0890 is capable of deliv-

ering Typical applications for the DAC0890 include opera-

tion with a microprocessor In this environment digital noise

is prevalent and anticipated Therefore special care must

be taken to ensure that proper operation will be achieved

The DAC0890 uses two ground pins AGND and DGND to

minimize ground drops and noise in the analog signal paths

Figure 3 details the proper bypassing and ground connec-

tions

The DAC0890’s best performance can be ensured by con-

necting 001 mFto0 1 mF ceramic capacitor in parallel with

AGND

Sense Inputs

The SENSE inputs (pins 13 and 19) allow compensation for

voltage drops in long output lines to remote loads This

places the drops in the internal amplifier’s feedback loop

An example of this is shown in

Figure 3 The I-R drop which

might be caused by printed circuit board traces or long ca-

placed inside the feedback loop if SENSE1 is connected

directly to the load This forces the voltage at the load to be

the correct value It is important to remember that the volt-

age at the DAC0890’s VOUT pins may become higher than

the full-scale output voltage selected using the SELECT

14 and 18) when the SENSE inputs are used

The SENSE inputs have a finite input impedance The

range-setting resistors load the output with 25 kX when the

0V to 255V range is selected and 10 kX when the 0V to

102V range is selected

TLH10592 – 10

FIGURE 3 Typical Connection Showing Power Supply

Bypassing and the Use of SENSE Inputs

9