TC818A Просмотр технического описания (PDF) - Microchip Technology
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TC818A Datasheet PDF : 24 Pages
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TC818A
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin Number
(64-Pin PQFP)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Symbol
Description
NC
No connection.
OHM Logic Input. “0” (Digital Ground) for resistance measurement.
20mA Logic Input. “0” (Digital Ground) for 20mA full scale current measurement.
BUZ
Buzzer. Audio frequency, 4kHz, output for continuity indication during resistance
measurement. A noncontinuous 4kHz signal is output to indicate an input over range
during voltage or current measurements.
XTAL1 32.768kHz Crystal Connection.
XTAL2 32.768kHz Crystal Connection.
VDISP
Sets peak LCD drive signal: VP - VDD-VDISP. VDISP may also be used to compensate for
temperature variation of LCD crystal threshold voltage.
BP1
LCD Backplane #1.
BP2
LCD Backplane #2.
BP3
LCD Backplane #3.
LOΩ/A
LCD Annunciator segment drive for low ohms resistance measurement and current
measurement.
Ω/V
LCD Annunciator segment drive for resistance measurement and voltage measurement.
k/m/HOLD LCD Annunciator segment drive for k (“kilo-Ohms”), m (“milliamps” and “millivolts”) and
HOLD mode.
BCP0 LCD segment drive for “b,” “c” segments and decimal point of least significant digit (LSD).
(One’s digit)
AGD0 LCD segment drive for “a,” “g,” “d” segments of LSD.
FE0
LCD segment drive for “f” and “e” segments of LSD.
NC
No connection.
BCP1 LCD segment drive for “b,” “c” segments and decimal point of 2nd LSD.
AGD1 LCD segment drive for “a,” “g,” “d” segments of 2nd LSD.
FE1
LCD segment drive for “f” and “e” segments of 2nd LSD.
BCP2
LCD segment drive for “b,” “c” segments and decimal point of 3rd LSD
(hundred’s digit).
AGD2 LCD segment drive for “a,” “g,” “d” segments of 3rd LSD.
FE2
LCD segment drive for “f,” “e” segments of 3rd LSD.
BCP3
LCD segment drive for “b,” “c” segments and decimal point of MSD,
(thousand’s digit).
AC/-/AUTO LCD annunciator segment drive for AC measurements, polarity, and auto-range operation.
-MEM/BATT LCD annunciator segment drive for AC for low battery indication and memory (relative
measurement).
ANNUNC
Square wave output at the backplane frequency, synchronized to BP1. ANNUNC can be
used to control display annunciators. Connecting an LCD segment to ANNUNC turns it on;
connecting it to its backplane turns it off.
VCC
COM
DEINT
Positive battery supply connection.
Analog circuit ground reference point. Nominally 3V below VCC.
De-integrate output.
RMREFL
CREFL
CREFH
REFHI
Ratiometric (resistance measurement) reference low voltage.
Reference capacitor negative terminal CREF = 0.1µf.
Reference capacitor positive terminal CREF = 0.1µf.
Reference voltage for voltage and current measurement. Nominally 163.85mV.
ΩR1
Standard resistor connection for 200Ω full scale.
ΩR2
Standard resistor connection for 2000Ω full scale.
© 2002 Microchip Technology Inc.
DS21475B-page 5
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