What is ADC0809?

ADC0809 is a CMOS process 8-channel, 8-bit successive approximation A / D converter manufactured by National Semiconductor. It has an internal 8-channel multiplexer that can latch the decoded signal based on the address code and only gate one of the eight analog input signals for A / D conversion. Is currently the most widely used 8 general-purpose A / D chip.

1.ADC0809 the main features

1) 8 input channels, 8-bit A / D converter, the resolution is 8 bits.

2) has a conversion start and stop control.

3) Conversion time is 100μs (clock is 640kHz), 130μs (clock is 500kHz)

4) Single +5 V power supply

5) Analog input voltage range 0 ~ + 5V, without zero and full scale calibration.

6) Operating temperature range of -40 ~ +85 degrees Celsius 7) Low power consumption, about 15mW.

2.ADC0809's internal structure

ADC0809 is a CMOS monolithic successive approximation A / D converter, the internal structure shown in Figure 13.22, which consists of 8 analog switches, address latch and decoder, comparator, 8-bit switch tree A / D converter Device, successive approximation register, logic control and timing circuit.

3.ADC0809's external features (pin function)

ADC0809 chip has 28 pins, dual in-line package, as shown in Figure 13.23. The following describes each pin function.

IN0 ~ IN7: 8 analog inputs.

2-1 ~ 2-8: 8-bit digital output.

ADDA, ADDB, ADDC: 3-bit address input lines for gating one of the 8 analog inputs

ALE: Address latch enable signal, input, active high.

START: A / D conversion start pulse input, enter a positive pulse (at least 100ns wide) to start (pulse rising edge 0809 reset, falling edge start A / D conversion).

EOC: A / D conversion end signal, output, when the A / D conversion is completed, this terminal outputs a high level (during the conversion has been low).

OE: Data output enable signal, input, active high. When the A / D conversion is finished, this end input a high level, in order to open the output tri-state gate, the output digital.

CLK: clock input. Requirements clock frequency is not higher than 640KHZ.

REF (+), REF (-): Reference voltage.

Vcc: power supply, single + 5V.

GND: ground.

 Author：Brittany Antonia （The author of article owns the copyright.）