TC818ACBU View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
TC818ACBU Datasheet PDF : 24 Pages
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TC818A
TABLE 2-1: PIN FUNCTION TABLE (CONTINUED)
Pin Number
(64-Pin PQFP)
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
Symbol
Description
ΩR3
ΩR4
ΩR5
VR3
VR2
VR5
VR4
VI
II
ACVL
CI
NC
CAZ
RX
CFI
ADI
ADO
RΩBUF
RVIBUF
ACVH
VSS
DGND
RANGE
HOLD
-MEM
DC(Ω)/
AC(LOΩ)
I
NC
Standard resistor connection for 20kΩ full scale range.
Standard resistor connection for 200kΩ full scale range.
Standard resistor connection for 2000kΩ full scale.
Voltage measurement ÷ 100 attenuator.
Voltage measurement ÷ 10 attenuator.
Voltage measurement ÷ 10,000 attenuator.
Voltage measurement ÷ 1000 attenuator.
Unknown voltage input ÷ attenuator.
Unknown current input.
Low output of AC-to-DC converter.
Integrator capacitor connection. Nominally 0.1µF. (Must have low dielectric absorption.
Polypropylene dielectric suggested.)
No connection.
Auto-zero capacitor connection. Nominally 0.1µF.
Unknown resistance input.
Input filter connection.
Negative input of internal AC-to-DC operational amplifier.
Output of internal AC-to-DC operational amplifier.
Active buffer output for resistance measurement. Integration resistor connection.
Nominally 220kΩ.
Active buffer output for voltage and current measurement. Integration resistor connection.
Nominally 15kΩ.
Positive output of AC-to-DC converter.
Negative supply connection. Connect to negative terminal of 9V battery.
Internal logic digital ground. Ground connection for the logic "0" level.
Nominally 4.7V below VCC.
Input to set manual operation and change ranges.
Input to hold display. Connect to DGND to "FREEZE" display.
Input to enter Memory Measurement mode for relative measurements. The two LSDs are
stored and subtracted from future measurements.
Input that selects AC or DC option during voltage/current measurements. For resistance
measurements, the ohms or low power (voltage) ohms option can be selected.
Input to select measurement. Connect to logic "0" (digital ground) for current measurement.
No connection.
3.0 DETAILED DESCRIPTION
3.1 Analog-to-Digital Converter (ADC)
The TC818A includes an integrating ADC with auto-
ranging resolution of 2000 counts and manual range
resolution of 3000 counts. Figure 3-1 shows a simpli-
fied schematic of the analog section. In Auto-Ranging
mode, internal logic will adjust the input voltage or
ohms attenuators so that measurements will always be
made in the appropriate range.
Measurement ranges, logic control inputs, 3-1/2 digit
LCD formatting, and other features are identical to the
TC818A auto-ranging A/D converter. However, the
TC818A is not pin compatible with, and is not a replace-
ment for, the TC818A.
A display annunciator output (ANNUNC) can be used
to customize the LCD. ANNUNC is a square wave at
the backplane frequency. Connecting an annunciator
segment to the ANNUNC driver turns the segment on;
connecting the segment to its backplane turns it off.
DS21475B-page 6
© 2002 Microchip Technology Inc.
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