TC7129 View Datasheet(PDF) - TelCom Semiconductor Inc => Microchip

Part Name

Description

Manufacturer

TC7129

4-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH ON-CHIP LCD DRIVERS

TelCom Semiconductor Inc => Microchip 

4-1/2 DIGIT ANALOG-TO-DIGITAL

CONVERTER WITH ON-CHIP LCD DRIVERS

INTEGRATE

DEINTEGRATE

1

TC7129

2

TIME

OVERSHOOT DUE TO ZERO CROSSING

BETWEEN CLOCK PULSES

INTEGRATOR RESIDUE VOLTAGE

3

ZERO

INTEGRATE

AND LATCH

CLOCK PULSES

OVERSHOOT CAUSED BY

COMPARATOR DELAY OF

1 CLOCK PULSE

Figure 10. Accuracy Errors in Dual-Slope Conversion

4

INT1

INTEGRATE

DE1

DEINTEGRATE REST X10 DE2 REST X10 DE3 ZERO INTEGRATE

5

TC7129

6

NOTE: Shaded area greatly expanded

in time and amplitude.

INTEGRATOR RESIDUAL VOLTAGE

Figure 11. Integrator Waveform

Digital Auto-Zeroing

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 mea-

surement 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.

Inside the TC7129

7

Figure 12 shows a simplified block diagram of the

TC7129.

Integrator Section

The integrator section includes the integrator, compara-

tor, input buffer amplifier, and analog switches used to

8 change the circuit configuration during the separate mea-

surement phases described earlier.

TELCOM SEMICONDUCTOR, INC.

3-241

Share Link: