TC820CPL Microchip Technology, TC820CPL Datasheet - Page 18

• Manufacturer Part Number: TC820CPL
• Description: IC ADC 3 3/4DGT LGC PROBE 40DIP
• Manufacturer: Microchip Technology

Specifications of TC820CPL

• 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: Through Hole
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -

TC820
FIGURE 5-4:
Circuit.
Where low cost is important, the RC circuit of
can be used. The frequency of this circuit will be
approximately:
EQUATION 5-1:
FIGURE 5-5:
Typical values are R = 10 kΩ and C = 68pF. The
resistor value should be ≥ 100 kΩ. For accurate
frequency measurement, an RC oscillator frequency of
40 kHz is required.
5.5
All system timing is derived from the clock oscillator.
The clock oscillator is divided by 2 prior to clocking the
A/D counters. The clock is also divided by 8 to drive the
buzzer, by 240 to generate the LCD backplane
frequency, and by 40,000 for the frequency counter
time-base. A simplified diagram of the system clock is
shown in
DS21476C-page 18
System Timing
Figure
37
37
5pF
5pF
22MΩ
40kHz
5-6.
T
OSC
110kΩ
Suggested Crystal Oscillator
RC Oscillator Circuit.
TC820
TC820
=
10pF
10pF
RC
0.3
38
38
470kΩ
75pF
Figure 5-5
39
39
FIGURE 5-6:
5.6
5.6.1
The value of the auto-zero capacitor (C
influence on system noise. A 0.47 µF capacitor is
recommended; a low dielectric absorption capacitor
(Mylar) is required.
5.6.2
The reference voltage capacitor used to ramp the
integrator output voltage back to zero during the
reference integrate cycle is stored on C
capacitor is typical. A good quality, low leakage
capacitor (such as Mylar) should be used.
Components
Components
Oscillator
Oscillator
Component Value Selection
XTAL
RC
AUTO-ZERO CAPACITOR - C
REFERENCE VOLTAGE
CAPACITOR - C
OSC1
System Clock Generation.
Time-Base
Backplane
© 2007 Microchip Technology Inc.
TC820
Counter
Counter
Buzzer
Driver
LCD
OSC2
A/D
REF
÷
AZ
OSC3
REF
÷
40,000
÷
÷
) has some
240
2
8
. A 0.1 µF
AZ