TC820CKW データシートの表示（PDF） - TelCom Semiconductor Inc => Microchip

部品番号

コンポーネント説明

メーカー

TC820CKW

3-3/4 DIGIT A/D CONVERTER WITH FREQUENCY COUNTER AND LOGIC PROBE

TelCom Semiconductor Inc => Microchip 

TC820

3-3/4 A/D CONVERTER WITH

FREQUENCY COUNTER

AND LOGIC PROBE

+9V

1M Ω

LOGIC

PROBE

INPUT

1M Ω

R1

VH –

+

R2

–

VL +

R3

1N4148

1N4148

VDD

LOGIC

DP1/HI

TC820

DP0/LO

+9V

10kΩ

TL061

VIN

1N4148

0.01µF

OFFSET

NULL

VDD

PK HOLD

VI+N TC820

VSS

DGND

0V

NOTE: Select R1, R2, R3 for desired logic thresholds.

Figure 22. Window Comparator Logic Probe

Figure 23. External Peak Detector

acitors added across the input pull-down resistors to stretch

the input pulse and permit viewing short-duration input

pulses.

depending on the displays values. Figure 25 shows a set of

waveforms for the a, g, d outputs of one digit for several

combinations of "on" segments.

External Peak Detection

The TC820 will hold the highest A/D conversion or

frequency reading indefinitely when the PK HOLD input is

connected to VDD. However, the analog peak input must be

present during the A/D converter's signal integrate period.

For slowly changing signals, such as temperature, the peak

reading will be properly converted and held.

If rapidly changing analog signals must be held, an

external peak detector should be added. An inexpensive

circuit can be made from an op amp and a few discrete

components, as shown in Figure 23. The droop rate of the

external peak detector should be adjusted so that the held

voltage will not decay below the desired accuracy level

during the converter's 400msec conversion time.

Liquid Crystal Display (LCD)

The TC820 drives a triplex (multiplexed 3:1) LCD with

three backplanes. The LCD can include decimal points,

polarity sign, and annunciators for overrange, peak hold,

high and low logic levels, and low battery. Table IV shows the

assignment of the display segments to the backplanes and

segment drive lines. The backplane drive frequency is

obtained by dividing the oscillator frequency by 240.

Backplane waveforms are shown in Figure 24. These

appear on outputs BP1, BP2, and BP3. They remain the

same regardless of the segments being driven.

Other display output lines have waveforms that vary

Table IV. LCD Backplane and Segment Assignments

44-Pin LCD

40-Pin DIP Flat Pkg Display

Pin No. Pin No. Pin No.

BP1 BP2 BP3

1

40

3

LOW "—"

2

41

4

A4 G4

3

42

5

B4 C4

4

43

6

HIGH F3

5

44

7

A3 G3

6

1

8

B3 C3

7

2

9

OVER F2

8

3

10

A2 G2

9

4

11

B2 C2

10

5

12

PEAK F1

11

6

13

A1 G1

12

7

14

B1 C1

13

8

2,16*

—

—

14

9

1

— BP2

15

10

15

BP1 —

*Connect both pins 2 and 16 of LCD to TC820 BP3 output.

E4

D4

DP3

E3

D3

DP2

E2

D2

DP1

E1

D1

BATT

BP3

—

—

3-168

TELCOM SEMICONDUCTOR, INC.

Share Link: