TC7129CPL Microchip Technology, TC7129CPL Datasheet - Page 9

• Manufacturer Part Number: TC7129CPL
• Description: IC ADC 4 1/2DGT LCD DVR 40-DIP
• Manufacturer: Microchip Technology

Specifications of TC7129CPL

• Display Type: LCD
• Configuration: 7 Segment
• Digits Or Characters: A/D 4.5 Digits
• Current - Supply: 800µA
• Voltage - Supply: 6 V ~ 12 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 40-DIP (0.600", 15.24mm)
• Resolution (bits): 4.5bit
• Input Channel Type: Differential
• Data Interface: Parallel
• Supply Current: 800µA
• Digital Ic Case Style: DIP
• No. Of Pins: 40
• Operating Temperature Range: 0°C To +70°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: TC7129CPLR; TC7129CPLR

3.0
(All Pin Designations Refer to 40-Pin PDIP.)
3.1
The TC7126A is a dual slope, integrating analog-to-
digital converter. An understanding of the dual slope
conversion technique will aid in following the detailed
TC7126/A operation theory.
The conventional dual slope converter measurement
cycle has two distinct phases:
• Input Signal Integration
• Reference Voltage Integration (De-integration)
The input signal being converted is integrated for a fixed
time period (T
pulses. An opposite polarity constant reference voltage
is then integrated until the integrator output voltage
returns to zero. The reference integration time is directly
proportional to the input signal (T
FIGURE 3-1:
In a simple dual slope converter, a complete conver-
sion requires the integrator output to “ramp-up” and
“ramp-down.”
©
2002 Microchip Technology Inc.
Analog
Signal
Voltage
Input
Integrate
REF
Signal
Fixed
Time
DETAILED DESCRIPTION
Dual Slope Conversion Principles
Polarity Control
SI
Variable
Reference
Integrate
Time
). Time is measured by counting clock
Display
Switch
Driver
Integrator
–
+
BASIC DUAL SLOPE
CONVERTER
Phase
Control
V
V
IN
IN
≈ V
≈ 1.2 V
–
+
RI
REF
Comparator
) (see Figure 3-1).
Control
REF
Logic
Counter
Clock
A simple mathematical equation relates the input sig-
nal, reference voltage and integration time:
EQUATION 3-1:
For a constant V
EQUATION 3-2:
The dual slope converter accuracy is unrelated to the
integrating resistor and capacitor values, as long as
they are stable during a measurement cycle. Noise
immunity is an inherent benefit. Noise spikes are inte-
grated or averaged to zero during integration periods.
Integrating ADCs are immune to the large conversion
errors that plague successive approximation converters
in high noise environments. Interfering signals with fre-
quency components at multiples of the averaging period
will be attenuated. Integrating ADCs commonly operate
with the signal integration period set to a multiple of the
50Hz/60Hz power line period (see Figure 3-2).
FIGURE 3-2:
Where:
V
T
T
SI
RI
R
30
20
10
0
= Reference voltage
= Signal integration time (fixed)
= Reference voltage integration time (variable)
0.1/t
RC
1
IN
V
∫
:
IN
T
0
SI
NORMAL MODE
REJECTION OF DUAL
SLOPE CONVERTER
=
V
Input Frequency
IN
V
(t)d
R
t = Measurement Period
1/t
TC7126/A
T
------ -
T
t
RI
=
SI
V
RC
R
T
RI
DS21458B-page 9
10/t