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PDF TC820 Data sheet ( Hoja de datos )
| Número de pieza | TC820 | |
| Descripción | 3-3/4 Digit A/D Converter with Frequency Counter and Logic Probe | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TC820 (archivo pdf) en la parte inferior de esta página. Total 28 Páginas | ||
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TC820
3-3/4 Digit A/D Converter with Frequency Counter
and Logic Probe
Features
• Multiple Analog Measurement System
- Digit A/D Converter
- Frequency Counter
- Logic Probe
• Low Noise A/D Converter:
- Differential Inputs: (1pA Bias Current)
- On-Chip 50ppm/°C Voltage Reference
• Frequency Counter:
- 4MHz Maximum Input Frequency
- Auto-Ranging Over Four Decade Range
• Logic Probe:
- Two LCD Annunciators
- Buzzer Driver
• 3-3/4 Digit Display with Over Range Indicator
• LCD Display Driver with Built-in Contrast Control
• Data Hold Input for Comparison Measurements
• Low Battery Detect with LCD Annunciator
• Under Range and Over Range Outputs
• On-Chip Buzzer Driver with Control Input
• 40-Pin Plastic DIP, 44-Pin Plastic Flat Pack, or
44-Pin PLCC Packages
Device Selection Table
Part
Number
Resolution
Package
Operating
Temp. Range
TC820CPL 3-3/4 Digits 40-Pin PDIP 0°C to +70°C
TC820CKW 3-3/4 Digits 44-Pin PQFP 0°C to +70°C
TC820CLW 3-3/4 Digits 44-Pin PLCC 0°C to +70°C
General Description
The TC820 is a 3-3/4 digit, multi-measurement system
especially suited for use in portable instruments. It inte-
grates a dual slope A/D converter, auto-ranging fre-
quency counter and logic probe into a single 44-pin
surface mount, or 40-pin through hole package. The
TC820 operates from a single 9V input voltage (bat-
tery) and features a built-in battery low flag. Function
and decimal point selection are accomplished with sim-
ple logic inputs designed for direct connection to an
external microcontroller or rotary switch.
© 2002 Microchip Technology Inc.
DS21476B-page 1
1 page  
TC820
TC820 ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Characteristics: VS = 9V, TA = 25°C, unless otherwise specified.
Symbol
Parameter
Min Typ
Max
Units
Test Conditions
TCZS
Zero Reading Drift
TCFS
Scale Factor Temperature
Coefficient
——
— 0.2
—1
——
—1
—5
— — VIN = 0V
— — 0°C ≤ TA ≤ +70°C
— — -40°C ≤ TA ≤ +85°C
— — VIN = 399mV
5 ppm/°C 0°C ≤ TA ≤ +70°C
— ppm/°C -40°C ≤ TA ≤ +85°C
Ext Ref = 0ppm/°C
IS Supply Current
—1
1.5 mA VIN = 0V
Peak-to-Peak Backplane
Drive Voltage
4.25
4.7
5.3 V VS = 9V
VDISP = DGND
Buzzer Frequency
—5
— kHz FOSC = 40kHz
Counter TIme-Base Period — 1
— Second FOSC = 40kHz
Low Battery Flag Voltage
6.7 7
7.3 V VDD to VSS
VIL Input Low Voltage
—
—
DGND + 1.5
V
VIH Input High Voltage
VDD – 1.5
—
—V
VOL Output Low Voltage,
UR, OR Outputs
VDD – 1.5 — DGND + 0.4 V IL = 50µA
Control Pin Pull-down Current
—
5
— µA VIN = VDD
Note 1: Input voltages may exceed the supply voltages provided that input current is limited to ±100µA. Current above this value
may result in invalid display readings, but will not destroy the device if limited to ±1mA.
2: Dissipation ratings assume device is mounted with all leads soldered to printed circuit board.
© 2002 Microchip Technology Inc.
DS21476B-page 5
5 Page 
TC820
3.2.7 10:1 RANGE CHANGE
The analog input full scale range can be changed with
the RANGE/FREQ input. Normally, RANGE/FREQ is
held low by an internal pull-down. Connecting this pin
to VS+ will increase the full scale voltage by a factor
of 10. No external component changes are required.
The RANGE/FREQ input operates by changing the
integrate period. When RANGE/FREQ is connected to
VDD, the signal integration phase of the conversion is
reduced by a factor of 10 (i.e., from 2000 counts to 200
counts).
For the TC820, the 10:1 range change will result in ±4V
full scale. This full scale range will exceed the Common
mode range of the input buffer when operating from a
9V battery. If range changing is required for the TC820,
a higher supply voltage can be provided, or the input
voltage can be divided by 2 externally.
3.3 Frequency Counter
In addition to serving as an analog-to-digital converter,
the TC820 internal counter can also function as a fre-
quency counter (Figure 3-3). In the Counter mode,
pulses at the RANGE/FREQ input will be counted and
displayed.
The frequency counter derives its time-base from the
clock oscillator. The counter time-base is:
EQUATION 3-5:
tCOUNT = FOSC
40,000
Thus, the counter will operate with a 1-second time-
base when a 40kHz oscillator is used. The frequency
counter accuracy is determined by the oscillator accu-
racy. For accurate frequency measurements, a crystal
oscillator is recommended.
The frequency counter will automatically select the
proper range. Auto-range operation extends over four
decades, from 3.999kHz to 3.999MHz. Decimal points
are set automatically in the Frequency mode (Figure 3-4).
The logic switching levels of the RANGE/FREQ input
are CMOS levels. For best counter operation, an exter-
nal buffer is recommended. See the applications sec-
tion for details.
3.4 Logic Probe
The TC820 can also function as a simple logic probe
(Figure 3-5). This mode is selected when the LOGIC
input is high. Two dual purpose pins, which normally
control the decimal points, are used as logic inputs.
Connecting either input to a logic high level will turn on
the corresponding LCD annunciator. When the "low"
annunciator is on, the buzzer will be on. As with the fre-
quency counter input, external level shifters/buffers are
recommended for the logic probe inputs.
FIGURE 3-3:
TC820 COUNTER OPERATION
LCD
Clock
Oscillator
TC820
From Integrator
of A/D Converter
÷2
Comparator
Data Latch, Peak Hold
Register, LCD
Decoder/Drivers
FREQ/
VOLTS
÷20,000
A/D Converter/Frequency
Counter Select
A/D Converter
Frequency Counter
Enable
3-3/4 Digit Counter
Count
Overflow
To Decimal
Point Drivers
Under Range
Control
RANGE/
FREQ
Frequency Input
Programmable
Divider
( ÷1, 10, 100, 1000)
Auto-Range
Control
Over Range
Detect
© 2002 Microchip Technology Inc.
DS21476B-page 11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet TC820.PDF ] | |
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