Abstract: In this paper two practical examples are used to demostrate the greatly possible exploitation of 3-1/2 digit monolithic A/D converter. One example is a pocket thermocuple thermometer matched with a k-type thermocouple, which temperature range arc from -50 to 1300℃, and the precision is 0.5 grade. Compared with 200mV digital millivoltmeter, it only 8 resistors are extended. Three resistors are added for another example if making a digital displaying meter. Not only it can display the measured value directly but also it can be used generally.