TC820CLW Microchip Technology, TC820CLW Datasheet - Page 11

• 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: -

The peak reading function is also available when the
TC820 is in the Frequency Counter mode. The counter
auto-ranging feature is disabled when peak reading
hold is selected.
3.2.7
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 V
10. No external component changes are required.
The RANGE/FREQ input operates by changing the
integrate period. When RANGE/FREQ is connected to
V
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
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.
FIGURE 3-3:
© 2007 Microchip Technology Inc.
DD
S
, the signal integration phase of the conversion is
+ will increase the full scale voltage by a factor of
RANGE/
VOLTS
FREQ/
FREQ
Frequency Counter
10:1 RANGE CHANGE
Frequency Input
A/D Converter/Frequency
TC820 Counter Operation.
Oscillator
Counter Select
Clock
÷20,000
( ÷1, 10, 100, 1000)
Programmable
÷2
Divider
From Integrator
of A/D Converter
Frequency Counter
A/D Converter
TC820
Comparator
The frequency counter derives its time-base from the
clock oscillator. The counter time-base is:
EQUATION 3-5:
Thus, the counter will operate with a 1-second time-
base when a 40 kHz oscillator is used. The frequency
counter accuracy is determined by the oscillator
accuracy. 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 3.999 kHz to 3.999 MHz. Decimal points
are set automatically in the Frequency mode
The logic switching levels of the RANGE/FREQ input
are CMOS levels. For best counter operation, an
external buffer is recommended. See the applications
section for details.
3.4
The TC820 can also function as a simple logic probe
(Figure
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
frequency counter input, external level shifters/buffers
are recommended for the logic probe inputs.
Point Drivers
To Decimal
Auto-Range
Control
3-5). This mode is selected when the LOGIC
Logic Probe
Enable
Count
Data Latch, Peak Hold
3-3/4 Digit Counter
Decoder/Drivers
Register, LCD
Under Range
t
Control
COUNT
LCD
Overflow
=
40,000
F
OSC
DS21476C-page 11
Over Range
TC820
Detect
(Figure
3-2).