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PDF TC818 Data sheet ( Hoja de datos )
| Número de pieza | TC818 | |
| Descripción | Auto-Ranging Analog-to-Digital Converter with 3-1/2 Digit Display | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TC818 (archivo pdf) en la parte inferior de esta página. Total 24 Páginas | ||
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TC818A
Auto-Ranging Analog-to-Digital Converter
with 3-1/2 Digit Display
Features
• Auto-Ranging Analog-to-Digital Converter with
3-1/2 Digit Display
• Annunciator Outputs Permit Customizing of LCD
• Auto-Range Operation for AC and DC Voltage
and Resistance Measurements
• Two User Selected AC/DC
• Current Ranges: 20mA and 200mA
• 22 Operating Ranges: 9 DC/AC Voltage
• 4 AC/DC Current
• 9 Resistance and Low Power Ohms
• Display Hold Function
• 3-1/2 Digit Resolution in Auto-Range
Mode: 1/2000
• Extended Resolution in Manual Range
Mode: 1/3000
• Internal AC-to-DC Conversion Op Amp
• Triplex LCD Drive for Decimal Points, Digits,
• Bar Graphs, and Annunciators
• Continuity Detection and Piezoelectric
Transducer Driver
• Low Drift Internal Reference: 75ppm/°C
• 9V Battery Operation: 10mW
• Low Battery Detection and LCD Annunciator
Device Selection Table
Part Number
TC818ACBU
Package
64-Pin PQFP
Operating
Temperature Range
0°C to +70°C
General Description
The TC818A is an integrating analog-to-digital con-
verter (ADC) with a 3-1/2 digit numeric LCD driver,
automatic ranging, and single 9V battery operation.
The numeric display provides 0.05% resolution and a
full set of annunciators that spell out the TC818A's
many operating modes.
Automatic range selection is provided for both voltage
(DC and AC) and ohms (high and low power) measure-
ments. Expensive and bulky mechanical range
switches are not required. Five full scale ranges are
available, with automatic selection of external volt/ohm
attenuators over a 1 to 10,000 range. Two current
ranges, 20mA and 200mA, can be manually selected.
The auto-range feature can be bypassed, allowing
input attenuator selection through a single line input.
During Manual mode operation, resolution is extended
to 3000 counts full scale. Extended resolution is also
available during 2000kΩ and 2000V full scale auto-
range operation. The extended range operation is indi-
cated by a flashing 1 MSD and by the fully extended bar
graph.
The TC818A includes an AC-to-DC converter for AC
voltage and current measurements. Only external
diodes/resistors/capacitors are required. Other fea-
tures include a Memory mode, low battery detection,
display HOLD input, and continuity buzzer driver.
The 3-1/2 digit numeric display includes a full set of
annunciators. Decimal points are adjusted as auto-
matic or manual range changes occur, and Voltage,
Current, and Ohms Operating modes are displayed.
Additional annunciators are activated for manual, auto,
memory, HOLD, AC, low power ohms, and low battery
conditions.
The TC818A is available in a surface mounted 64-pin
flat package. Combining a numeric display driver, sin-
gle 9V battery operation, internal range switching, and
compact surface mounting, the TC818A is ideal for
advanced portable instruments.
© 2002 Microchip Technology Inc.
DS21475B-page 1
1 page  
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
5 Page 
TC818A
FIGURE 3-4:
BASIC TC818A CONVERSION TIMING
TC818A
Auto-Zero
Phase
Signal
INT
Phase
REF
DEINT
Phase
Next Conversion
Auto-Zero Cycle
Extended Resolution
Zero Crossing
External Crystal = 32.768kHz
Internal Clock Period = tP = 2/32.768 = 61.04µsec
Total Conversion Time = tCONV = 8000(tP)
= 488.3msec ≈ 2 conv/sec
Min. Auto-Zero
Time
3361.5tP
Fixed
1638.5tP
tI
*Max.
3000tP
tDE
tCONV = 8000tP
µTo
Input
Signal
*In Auto-Range Operation, Maximum
is 2000tP and minimum Auto-Zero Time is 4361.5tP
Integration Time = TI = 1638.5(tP) = 100msec
Maximum Reference De-integrate Time
= tDE 3000(tP) = 183.1msec
(manual extended resolution)
= 2000(tP) = 122.1msec (auto-range)
Maximum Auto-Zero Time
= (8000 - 3000 - 1638.5)
(tP) = 205.1msec (manual extended resolution)
= (8000 - 3000 - 1638.5)
(tP) = 205.1msec (manual extended resolution)
3.9 Manual Range Selection
The TC818A voltage and resistance auto-ranging fea-
ture can be disabled by momentarily bringing RANGE
(Pin 59) to digital ground potential (Pin 58). When the
change from auto-to-manual ranging occurs, the first
manual range selected is the last range in the Auto-
Ranging mode.
The TC818A power-up circuit initially selects auto-
range operation. Once the manual range option is
entered, range changes are made by momentarily
grounding the RANGE control input. The TC818A
remains in the Manual Range mode until the measure-
ment function (voltage or resistance), or measurement
option (AC/DC, Ω/LOΩ) changes. This causes the
TC818A to return to auto-ranging operation.
The “Auto” LCD annunciator driver is active only in the
Auto-Range mode.
Figure 3-5 shows typical operation where the manual
range selection option is used. Also shown is the
extended resolution display format. Also, see Figure 3-6
and Figure 3-7.
FIGURE 3-5:
MANUAL RANGE
SELECTION RESISTANCE
MEASUREMENTS
Continuity
Indicator
Output 4kHz
Audio
Frequency
Continuous
4kHz Buzzer
Manual
Range
Select
Yes Is
RX < 19
?
No Over Range
Indicator
Is
RX > 3000
?
Yes
Display
"1" 000
No
"1" = > Flashing
MSD
Is
RX > 2000
?
No
Display
True
Reading
Yes*
Display Last
3 Digits and
Flash MSD
Extended Resolution
Feature
*Mode also operates when Auto-Ranging Operator is selected
and 2MΩ < RX < 2.999MΩ.
© 2002 Microchip Technology Inc.
DS21475B-page 11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet TC818.PDF ] | |
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