TC811 查看數據表（PDF） - TelCom Semiconductor Inc => Microchip

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TC811

3-1/2 DIGIT A/D CONVERTER WITH HOLD AND DIFFERENTIAL REFERENCE INPUTS

TelCom Semiconductor Inc => Microchip 

3-1/2 DIGIT A/D CONVERTER WITH HOLD AND

DIFFERENTIAL REFERENCE INPUTS

1

Liquid Crystal Display Sources

Several LCD manufactures supply standard LCD dis-

plays to interface with the TC811 3-1/2 digit analog-to-digital

converter.

Manufacturer Address/Phone

Representative

Part Numbers*

Crystaloid

Electronics

5282 Hudson Dr.,

Hudson, OH 44236

216-655-2429

C5335, H5535,

T5135, SX440

AND

770 Airport Blvd.,

Burlingame, CA 94010

415-347-9916

FE 0801,

FE 0203

EPSON

3415 Kashikawa St.,

Torrence, CA 90505

212-534-0360

LD-B709BZ

LD-H7992AZ

Hamlin, Inc.

612 E. Lake St.,

Lake Mills, WI 53551

414-648-2361

3902, 3933, 3903

*NOTE: Contact LCD manufacturer for full product listing/specifications.

TC811

9V

+

26

38

V–

V+

TC811

240kΩ

VR+EF 36

VREF

VR– EF 33

ANALOG 32

COMMON

10kΩ

SET VREF = 1/2 VFULL SCALE

Figure 10. TC811 Internal Voltage Reference Connection

2

3

4

Oscillator Crystal Source

Manufacturer

STATEK

Address/Phone

512 N-Main

Orange, CA 92668

714-639-7810

Representative

Part Numbers

CX-1V 40.0

Ratiometric Resistance Measurements

The TC811 true differential input and differential refer-

ence make ratiometric readings possible. In ratiometric

operation, an unknown resistance is measured with respect

to a known standard resistance. No accurately defined

reference voltage is needed.

The unknown resistance is put in series with a known

standard and a current is passed through the pair (Figure

11). The voltage developed across the unknown is applied

to the input and the voltage across the known resistor

applied to the reference input. If the unknown equals the

standard, the input voltage will equal the reference voltage

and the display will read 1000. The displayed reading can be

determined from the following expression:

Displayed reading = RUNKNOWN x 1000

RSTANDARD

The display will overrange for RUNKNOWN ≥ 2 X

RSTANDARD.

RSTANDARD

RUNKNOWN

VR+EF V+ HLDR

VR–EF

VI+N

TC811

LCD

5

VI–N

ANALOG

COMMON

6

Figure 11. Low Parts Count Ratio Metric Resistance Measurement

7

8

TELCOM SEMICONDUCTOR, INC.

3-147

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