TC7129CKW713 Microchip Technology, TC7129CKW713 Datasheet - Page 13

• Manufacturer Part Number: TC7129CKW713
• Description: IC ADC 4 1/2DGT LCD DVR 44-MQFP
• Manufacturer: Microchip Technology

Specifications of TC7129CKW713

• 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: Surface Mount
• Package / Case: 44-MQFP, 44-PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -

4.8
The successive integration technique picks up where
dual-slope conversion ends. The overshoot voltage
shown in Figure 4-9 (called the “integrator residue
voltage”) is measured to obtain a correction to the initial
count. Figure 4-10 shows the cycles in a successive
integration measurement.
The waveform shown is for a negative input signal. The
sequence of events during the measurement cycle is
shown in Table 4-1.
TABLE 4-1:
© 2006 Microchip Technology Inc.
Phase
REST Rest; circuit settles.
REST Rest; circuit settles.
INT
DE
X10
DE
X10
DE
1
2
3
1
Input signal is integrated for fixed time (1000 clock
cycles on 2V scale, 10,000 on 200 mV).
Integrator voltage is ramped to zero. Counter
counts up until zero-crossing to produce reading
accurate to 3-1/2 digits. Residue represents an
overshoot of the actual input voltage.
Residue voltage is amplified 10 times and
inverted.
Integrator voltage is ramped to zero. Counter
counts down until zero-crossing to correct reading
to 4-1/2 digits. Residue represents an undershoot
of the actual input voltage.
Residue voltage is amplified 10 times and
inverted.
Integrator voltage is ramped to zero. Counter
counts up until zero-crossing to correct reading to
5-1/2 digits. Residue is discarded.
Successive Integration
MEASUREMENT CYCLE
SEQUENCE
Description
4.9
To eliminate the effect of amplifier offset errors, the
TC7129 uses a digital auto-zeroing technique. After the
input voltage is measured as described above, the
measurement is repeated with the inputs shorted
internally. The reading with inputs shorted is a
measurement of the internal errors and is subtracted
from the previous reading to obtain a corrected
measurement. Digital auto-zeroing eliminates the need
for an external auto-zeroing capacitor used in other
ADCs.
4.10
Figure 4-11 shows a simplified block diagram of the
TC7129.
Digital Auto-Zeroing
Inside the TC7129
TC7129
DS21459D-page 13