Figure 9-5 shows the ADC0816/17 connected for simple absolute conversion. Absolute conversion refers to the use of transducers with which the output value is not related to another voltage. The "absolute" value of the output voltage is very important (in contrast to the output voltage of a ratiometric transducer). This implies that the reference must be accurate to determine the value of the absolute output of the transducer. A precise, adjustable reference is provided by an LM336-5.0 and the associated parts. Ratiometric transducers can also be used in this circuit, and in most of the following data-conversion circuits. However, the key point to remember is that accuracy of absolute conversion depends primarily on the accuracy of the reference voltage. With ratiometric systems (Fig. 9-4), accuracy is determined by the transducer characteristics. NATIONAL SEMICONDUCTOR, APPLICATION NOTE 259, 1994, P. 594.
The ADC0816, ADC0817 data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital converter, 16-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses successive approximation as the conversion technique. The converter features a high impedance chopper stabilized comparator, a 256R voltage divider with analog switch tree and a successive approximation register. The 16-channel multiplexer can directly access any one of 16-single-ended analog signals, and provides the logic for additional channel expansion. Signal conditioning of any analog input signal is eased by direct access to the multiplexer output, and to the input of the 8-bit A/D converter.
The device eliminates the need for external zero and full-scale adjustments. Easy interfacing to microprocessors is provided by the latched and decoded multiplexer address inputs and latched TTL TRI-STATE® outputs. The design of the ADC0816, ADC0817 has been optimized by incorporating the most desirable aspects of several A/D conversion techniques. The ADC0816, ADC0817 offers high speed, high accuracy, minimal temperature dependence, excellent long-term accuracy and repeatability, and consumes minimal power. These features make this device ideally suited to applications from process and machine control to consumer and automotive applications. For similar performance in an 8-channel, 28-pin, 8-bit A/D converter, see the ADC0808, ADC0809 data sheet. (See AN-258 for more information.)
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Easy interface to all microprocessorsOperates ratiometrically or with 5 VDC or analog span adjusted voltage reference16-channel multiplexer with latched control logicOutputs meet TTL voltage level specifications0V to 5V analog input voltage range with single 5V supplyNo zero or full-scale adjust requiredStandard hermetic or molded 40-pin DIP packageTemperature range −40˚C to +85˚C or −55˚C to +125˚CLatched TRI-STATE outputDirect access to "comparator in" and "multiplexer out" for signal conditioningADC0816 equivalent to MM74C948ADC0817 equivalent to MM74C948-1
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Supply Voltage (VCC) (Note 3) 6.5V
Voltage at Any Pin −0.3V to (VCC+0.3V)
Except Control Inputs
Voltage at Control Inputs −0.3V to 15V
(START, OE, CLOCK, ALE, EXPANSION CONTROL,
ADD A, ADD B, ADD C, ADD D)
Storage Temperature Range −65˚C to + 150˚C
Package Dissipation at TA = 25˚C 875 mW
Post a Buying Lead
Required Field 
