The ADC ADC data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital con- verter 8-channel multiplexer and. ADC ADC – 8-bit Microprocessor Compatible A/D Converters With 8- Channel Multiplexer, Details, datasheet, quote on part number: ADC The ADC/ADC Data Acquisition Devices (DAD) implement on a single chip most the elements of the stan- dard data acquisition system. They contain.

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The source resistance must be below 10kohms for operation below kHz and below 5kohms for operation around 1. The source code provided was used to control an ADC where only 4 inputs were used, therefore, ADD C is tied to ground and so are the unused inputs.

National Semiconductor

Top rail of Reference voltage. Signal from the ADC. The maximum frequence of the clock is 1. This is a bit of the digital converted output. Bottom rail of Reference voltage. Once loaded the multiplexer sends the appropriate channel to the converter on the chip.

The ADC stores the data in a tri-state output latch until the next conversion is started, but the data is only output when enabled. Start The purpose of the start signal is two fold. As with all control signals it is required to have an input value of Vcc – 1. The ALE should be pulsed for at least ns in order for the addresses to get loaded properly.


This means it satasheet remain stable for up to 72 clock cycles. The signal can be tie to the ALE signal when the clock frequency is below kHz. For a quick reference refer to table 2. Address Lines Because the chip has an 8 channel multiplexer there are three address select lines: It is the Second bit of the select lines. Like the ALE pulse the minimum pulse width is ns.

See table 1 for details. There are 8, 8 clock cycle periods required in order to complete an entire conversion.

You will also need to download multiplex. Be sure to consult the manufactures data-sheets for other chips. It is the MSB of the select lines.

Up to 72 if datadheet start signal is received in the middle of an 8 clock cycle period. Note that it can take up to 2. It goes daasheet when a conversion is started and high at the end of a conversion.

Clock The clock signal is required to cycle through the comparator stages to do the conversion.

On the rising edge of the pulse the internal registers are cleared and on the falling edge of the pulse the conversion is initiated. Table 2 provides a summary of all of the input and output to the chip. This is an address select line datazheet the multiplexer. Unfortunately you cannot just hook up analog inputs to an ADC and expect to get digital outputs from the chip without adding control signals.


A, B, and C. At clock speeds greater than that the user must make certain that enough time has passed since the ALE signal was pulsed so that the correct address is loaded into the multiplexer before a conversion begins.

Control signal from FPGA. The following control signals are used to control the conversion. The source must remain datazheet while it is being sampled and should contain little noise.

National Semiconductor – datasheet pdf

The clock should conform to the same range as all other control signals. It is a control signal from the FPGA, which tells the converter when to start a conversion. All of the signals are explained below.

Begin by downloading the files into your desired destination directory and then compile them in this order. It is recomended that the source resistance not exceed 5kohms for operation at 1. C is the daatasheet significant bit and A is the least. The start signal should conform to the same range as all other control signals.