Posted on May 25, 2012 6858
Circuits to interlace the Si7135 directly with two popular microprocessors are shown in Figs. 18-2a and b. The 8080/8048 and the MC6800 families with 8-bit words need to have polarity, overrange, and underrange multiplexed onto the digit 5 word. In each case, the microprocessor can instruct the ADC when to begin a measurement and when to hold this measurement. The Si7135 is designed to work from Â±5 V supplies.
However, if a negative supply is not available, it can be generated using 2 capacitors, and an inexpensive Si7660 or Si7661 IC, as shown in Fig. 18-2c.