TC820CLW Просмотр технического описания (PDF) - TelCom Semiconductor Inc => Microchip

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Компоненты Описание

производитель

TC820CLW

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

TelCom Semiconductor Inc => Microchip 

3-3/4 A/D CONVERTER WITH

FREQUENCY COUNTER

AND LOGIC PROBE

BP1

BP2

BP3

Figure 24. Backplane Waveforms

SEGMENT

LINE

ALL OFF

VDD

VH

VL

VDISP

a SEGMENT

ON

d, g OFF

VDD

VH

VL

VDISP

a, g ON

d OFF

VDD

VH

VL

VDISP

ALL ON

VDD

VH

VL

VDISP

Figure 25. Typical Display Output Waveforms

HIGH OVER PEAK BATT

LOW

1

TC820

LCD Source

2 Although most users will design their own custom LCD,

a standard display for the TC820 (Figure 26), Part No. ST-

1355-M1, is available from:

Crystaloid (USA)

Crystaloid Electronics

P.O. Box 628

5282 Hudson Dr.

Hudson, OH 44238

Phone: (216) 655-2429

Fax: (216) 655-2176

Crystaloid (Europe)

Rep France

102, rue des Nouvelles

F92150 Suresnes

France

Phone: 33-1-42 04 29 25

Fax: 33-1-45 06 46 99

3

Annunciator Output

The annunciator output is a square wave running

at the backplane frequency (for example, 167Hz when

fOSC = 40kHz). The peak-to-peak amplitude is equal to (VDD

– VDISP). Connecting an annunciator of the LCD to the

annunciator output turns it on; connecting it to its backplane

4

turns it off.

LCD Drive Voltage (VDISP)

The peak-to-peak LCD drive voltage is equal to (VDD –

VDISP). In the 40-pin dual-in-line package (DIP), VDISP is

5 internally connected to DGND, providing a typical LCD drive

voltage of 5VP-P.

For applications with a wide temperature range, some

LCDs require that the drive levels vary with temperature to

maintain good viewing angle and display contrast. In this

case, the TC820 44-pin package provides a pin connection

for VDISP. Figure 27 shows TC820 circuits that can be

adjusted to give a temperature compensation of about

6 10mV/°C between VDD and VDISP. The diode between GND

and VDISP should have a low turn-on voltage because VDISP

cannot exceed 0.3V below GND.

Crystal Source

Two sources of the 40 kHz crystal are:

Statek Corp.

512 N. Main St.

Orange, CA 92668

Phone: (714) 639-7810

Fax: (714) 997-1256

Part #: CX-1V-40.0

SPK Electronics

2F-1, No. 312, Sec. 4,

Jen Ai Rd

Taipei, Taiwan R.O.C.

7

Phone: (02) 754-2677

Fax: 886-2-708-4124

Part#: QRT-38-40.0kHz

PIN 1

Figure 26. Typical TC820 LCD

TELCOM SEMICONDUCTOR, INC.

8

3-169

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