TC820CLW Microchip Technology, TC820CLW Datasheet - Page 8

• Manufacturer Part Number: TC820CLW
• Description: IC ADC 3 3/4DGT LGC PROBE 44PLCC
• Manufacturer: Microchip Technology

Specifications of TC820CLW

• Display Type: LCD
• Configuration: 7 Segment + 2 Annunciators
• Digits Or Characters: A/D 3.75 Digits
• Current - Supply: 1mA
• Voltage - Supply: 9V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -

TC820
3.0
The is a 3-3/4 digit measurement system combining an
integrating
counter, and logic level tester in a single package. The
TC820 supersedes the TC7106 in new designs by
improving performance and reducing system cost. The
TC820 adds features that are difficult, expensive, or
impossible to provide with older A/D converters (see
Table
based instruments to deliver higher performance and
more features, while actually reducing parts count.
Fabricated in low power CMOS, the TC820 directly
drives a 3-3/4 digit (3999 maximum) LCD.
With a maximum range of 3999 counts, the TC820
provides 10 times greater resolution in the 200 mV to
400 mV range than traditional 3-1/2 digit meters. An
auto-zero cycle ensures a zero reading with a 0V input.
CMOS processing reduces analog input bias current to
only 1 pA. Rollover error (the difference in readings for
equal magnitude but opposite polarity input signals) is
less than ±1 count. Differential reference inputs permit
ratiometric
transducer applications.
The TC820's frequency counter option simplifies
design of an instrument well-suited to both analog and
digital troubleshooting: voltage, current, and resistance
measurements, plus precise frequency measurements
to 4MHz (higher frequencies can be measured with an
external prescaler), and a simple logic probe. The
frequency counter will automatically adjust its range to
match the input frequency, over a four-decade range.
Two logic level measurement inputs permit a TC820
based meter to function as a logic probe. When
combined with external level shifters, the TC820 will
display logic levels on the LCD and also turn on a
piezoelectric buzzer when the measured logic level is
low.
Other TC820 features simplify instrument design and
reduce parts count. On-chip decimal point drivers are
included, as is a low battery detection annunciator. A
piezoelectric buzzer can be controlled with an external
switch or by the logic probe inputs. Two oscillator
options are provided: a crystal can be used if high
accuracy frequency measurements are desired, or a
simple RC option can be used for low-end instruments.
the highest A/D or frequency reading. This feature is
useful in measuring motor starting current, maximum
temperature, and similar applications.
A family of instruments can be created with the TC820.
No additional design effort is required to create
instruments with 3-3/4 digit resolution.
The TC820 operates from a single 9V battery, with
typical power of 10mW. Packages include a 40-lead
plastic DIP, 44-lead plastic flat package (PQFP), and
44-lead PLCC.
DS21476C-page 8
A "peak reading hold" input allows the TC820 to retain
3-1). The high level of integration permits TC820
DETAILED DESCRIPTION
measurements
analog-to-digital
for
converter,
ohms
or
frequency
bridge
TABLE 3-1:
3.1
3.1.1
The TC820 analog-to-digital converter operates on the
principle of dual slope integration. An understanding of
the dual slope conversion technique will aid the user in
following the detailed TC820 theory of operation
following this section. A conventional dual slope con-
verter measurement cycle has two distinct phases:
1.
2.
Referring to
converted is integrated from zero for a fixed time period
(t
reference voltage of the opposite polarity is then
integrated until the integrator output voltage returns to
zero. The reference integration (de-integration) time
(t
input voltage (V
3-3/4 Digit Resolution
Auto-Ranging Frequency
Counter
Logic Probe
Decimal Point Drive
Peak Reading Hold
(Frequency or Voltage)
Display Hold
Simple 10:1 Range Change
Buzzer Drive
Low Battery Detection
with Annunciator
Over Range Detection
with Annunciator
Low Drift Reference
Under Range/Over Range
Logic Output
Input Overload Display
LCD Annunciator Driver
LCD Drive Type
LCD Pin Connections
LCD Elements
INT
DEINT
Features Comparison
), measured by counting clock pulses. A constant
Input Signal Integration.
Reference Voltage Integration (De-integration).
) is then directly proportional to the unknown
General Theory of Operation
DUAL SLOPE CONVERSION
PRINCIPLES
Figure
IN
).
COMPETITIVE EVALUATION
3-1, the unknown input signal to be
© 2007 Microchip Technology Inc.
Triplexed
TC820
"OL"
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
15
36
Direct
7106
No
No
No
No
No
No
No
No
No
No
No
No
"1"
No
24
23