Direct voltage tester and method for testing direct voltage

The invention discloses a direct voltage tester and a method for testing direct voltage. The direct voltage tester comprises a high-resolution analog-digital converter, a high-precision regulated power supply and a serial port output circuit. The high-precision regulated power supply and the serial port output circuit are respectively connected with the high-resolution analog-digital converter. The high-resolution analog-digital converter compares reference voltage of the high-precision regulated power supply with the received input voltage to obtain comparison data, and then converts the comparison data to digital signals and outputs the digital signals through the serial port output circuit. Because resolution ratio is very high and cost is very low, the selected analog-digital converter has very low rate of conversion, but measurement of stable direct voltage is not affected. Serial port output of digital signals can enable the voltage tester to be integrated with other systems conveniently. With the help of a single chip microcomputer or a master control computer, an input voltage value can be quickly obtained, utilized and calculated. Therefore, when the direct voltage tester is used, testing cost of direct voltage is remarkably reduced, structure is simple and precision is high.