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Using ADC0816 As Standalone

Anonymous
Anonymous

Hi,

I'm using ADC0816 in standalone mode.

VCC = 5 V

GND = 0 V

V ref + = VCC

V ref - =  GND

CLK = 20 Khz using 555; 

A = HIGH

B = C = D = LOW

INO is being given the Analog Input from 0 - VCC

Questions :

1) First ADC0816 works in standalone mode?

2) I do get some low high output at the digital PINs on oscilloscope. Like : Out of D0-D7 some are high some are low.

     However I'm not able to understand whether that is the correct output for that particular Analog input or not.

     After noting down the digital output shall I directly convert the the binary to digital or its not that way in ADC.

     Sometimes I get different output at Digital Pins for the same analog input.

3) In standalone EOC,SC, ALE & OE should be given inputs ?

Please let me know how to make standalone mode for ADC0816 work? 

  • 0
    TI__Mastermind 44680 points

    Hi

    I would recommend you review Application Note 258. It covers a lot of different circuits for the ADC0816 and ADC0817 to interface to different 'vintage' microprocessors. A simplified version of the circuitry in Figure 28 is probably close to what you need for standalone operation. As the ADC0816 datasheet states, you can use the EOC output to drive the START (also called SC) and ALE inputs to cause continuous standalone conversions. You do need to create an initial Low to High transition on the START input before this will happen however. So you should probably use a logic gate to combine your initial Start Pulse with the EOC output into one signal that drives the START input as needed.

    This should be a link to Application Note 258: http://www.ti.com/lit/an/snoa596/snoa596.pdf

    Also, since the outputs will update periodically and are not valid while in transition, you will want to ignore the output data when the EOC signal is high. OE can be tied high as long as the data outputs of the ADC0816 are the only outputs on the bus.

    I hope this is helpful.

    Best regards,

    Jim B

  • Anonymous
    0 Anonymous in reply to Jim Brinkhurst1

    Hi,

    Thanks Jim B for the reply.

    What if I keep opt for this configuration : 

    1) ALE = VCC

    2) OE = VCC

    3) EOC Connected To SC/START

    4) SC/START = HIGH to LOW

    So, I'll apply the analog input to lets say IN0 with SC/START at HIGH Condition and at that analog input only I will change SC/START to LOW, that should give me the digital output at D0-D7 ?

    Thanks