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Functional Description (Continued)

This zener is intended for use as a shunt voltage regulator

to eliminate the need for any additional regulating compo-

nents. This is most desirable if the converter is to be re-

motely located from the system power source.

Figures 4

and 5

illustrate two useful applications of this on-board ze-

ner when an external transistor can be afforded.

An important use of the interconnecting diode between V

and V

is shown in

Figures 6 and 7

. Here, this diode is

used as a rectifier to allow the V

supply for the converter

to be derived from the clock. The low current requirements

of the A/D and the relatively high clock frequencies used

(typically in the range of 10k–400 kHz) allows using the

small value filter capacitor shown to keep the ripple on the

line to well under (/4 of an LSB. The shunt zener regula-

tor can also be used in this mode. This requires a clock

voltage swing which is in excess of V

. A current limit for the

zener is needed, either built into the clock generator or a

resistor can be used from the CLK pin to the V

pin.

Applications

TL/H/5583–12

FIGURE 4. Operating with a Temperature

Compensated Reference

TL/H/5583–34

FIGURE 5. Using the A/D as

the System Supply Regulator

TL/H/5583–35

FIGURE 6. Generating V

from the Converter Clock

TL/H/5583–36

FIGURE 7. Remote SensingÐ

Clock and Power on 1 Wire

*Note: 4.5V

6.3V

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