AD664 datasheet(19/20 Pages) AD

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AD664

REV. C

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Figure 29. AD664 in “Tester-per-Pin” Architecture

APPLICATIONS OF THE AD664

“Tester-Per-Pin” ATE Architecture

Figure 29 shows the AD664 used in a single channel of a digital

test system. In this scheme, the AD664 supplies four individual

output voltages. Two are provided to the VHIGH and VLOW in-

puts of the AD345 pin driver I.C. to set the digital output levels.

Two others are routed to the inputs of the AD96687 dual com-

parator to supply reference levels of the readback features. This

approach can be replicated to give as many channels of stimulus/

readback as the tester has pins. The AD664 is a particularly

appropriate choice for a large-scale system because the low

power requirements (under 500 mW) ease power supply and

cooling requirements. Analog ground currents of 600

µA or less

make the ground current management task simpler. All DACs

can be driven from the same system reference and will track

over time and temperature. Finally, the small board area

required by the AD664 (and AD345 and AD96687) allows a

high functional density.

X-Y Plotters

Figure 30 is a block diagram of the control section of a

microprocessor-controlled X-Y pen plotter. In this conceptual

exercise, two of the DACs are used for the X-channel drive and

two are used for the Y-channel drive. Each provides either the

coarse or fine movement control for its respective channel. This

approach offers increased resolution over some other approaches.

A designer can take advantage of the reset feature of the AD664

in the following manner. If the system is designed such that the

“HOME” position of the pen (or galvanometer, beam, head or

similar mechanism) results when the outputs of all of the DACs

are at zero, then no system software is required to home the

pen. A simple reset signal is sufficient.

Similarly, the transparent feature could be used to the same

end. One code can be sent to all DACs at the same time to send

the pen to the home position. Of course, this would require

some software where the previous example would require only a

single reset strobe signal!

Drawing scaling can be achieved by taking advantage of the

AD664’s software programmable gain settings. If, for example,

an “A” size drawing is created with gain settings of 1, then a

“C” size drawing can be created by simply resetting all DAC

gains to 2 and redrawing the object. Conversely, a “C” size

drawing created with gains of 2 can be reduced to “A” size sim-

ply by changing the gains to 1 and redrawing. The same princi-

pal applies for conversion from “B” size to “D” size or “D” size

to “B” size. The multiplying capability of the AD664 provides

another scaling option. Changing the reference voltage provides

a proportional change in drawing size. Inverting the reference

voltage would invert the drawing.

Swapping digital input data from the X channel to the Y chan-

nel would rotate the drawing 90 degrees.

Figure 30. X-Y Plotter Block Diagram

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