SC7106/7107

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:1.2

2006.02.27

Http: www.silan.com.cn

Page 7 of 22

TYPICAL INTEGRATOR AMPLIFIER OUTPUT WAVEFORM (INT PIN)

FUNCTIONAL DESCRIPTION

1. ANALOG SECTION

Figure 3 shows the Analog Section for the SC7106 and SC7107. Each measurement cycle is divided into three

phases. They are (1) auto-zero (A-Z), (2) signal integrate (INT) and (3) de-integrate (DE).

FIGURE 3. ANALOG SECTION OF SC7106 AND SC7107

2. AUTO-ZERO PHASE

During auto-zero three things happen. First, input high and low are disconnected from the pins and internally

shorted to analog COMMON. Second, the reference capacitor is charged to the reference voltage. Third, a

feedback loop is closed around the system to charge the auto-zero capacitor CAZ to compensate for offset

voltages in the buffer amplifier, integrator, and comparator. Since the comparator is included in the loop, the A-Z

accuracy is limited only by the noise of the system. In any case, the offset referred to the input is less than 10

µV.