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Maxim > Design Support > Technical Documents > Application Notes > A/D and D/A Conversion/Sampling Circuits > APP 1138
Maxim > Design Support > Technical Documents > Application Notes > Amplifier and Comparator Circuits > APP 1138
Keywords: DAQ, data acquisition, windows-based, pc-based, ADC, analog to digital converter, ADCs,
converters, RS232, AVR, resistor divider, resistive divider, signal conditioning, rs-232
APPLICATION NOTE 1138
Practical Data Acquisition using a Windows¹-based
Power Meter
Jul 03, 2002
Abstract: This application note describes the design of a PC-based, 14-bit data acquisition system. It
takes a system approach, includes all the necessary building blocks: analog, digital, hardware, and
software. It discusses each step, testing systems separately before integrating them, and detailing pitfalls
learned along the way.
Many articles have been written about the building blocks in a typical data acquisition system, but few
address the entire system, from analog input to PC display. To cover all the problems encountered in
designing a complete data acquisition system, the engineer might have to amass ten articles.
The following application note describes the design of a PC-based, 14-bit data acquisition system. It
takes a system approach, includes all the necessary building blocks: analog, digital, hardware, and
software. It discusses each step, testing systems separately before integrating them, and detailing pitfalls
learned along the way.
The Design Specification
The task: Design a power meter based on a 14-bit simultaneous-sampling ADC with on-chip RAM
(MAX125).
The need for a power meter is apparent to anyone who has tried measuring the input and output
characteristics of a DC-DC converter using conventional instruments. The design allows users to perform
load measurements on the device under test without connecting an endless spaghetti-mass of test leads.
Figure 1 shows the completed power meter display on a personal computer (PC) monitor.
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