Problem with ADC0808CCN

Thread Starter

arivalagan13

Joined Apr 30, 2009
29
Hi group..
I hope everyone is doing well..
I got a problem with ADC circuit..
Before my problem kindly have a look at the circuit I used to test the ADC with attachments..
I'm using ADC0808CCN,which is a 8-channel ADC..
I need to use 4(out of 8) channels for my application..

Before doing that I decided to test one channel by the manner shown in the circuit diagram that I attached..

But the conversion is not taking place...

I'm getting strange responses...which I can't even explain
I used 640kHz clock(also tried with 550kHz)..

I'm getting the same response with and without the clock..

Kindly help me to sort out this problem..



Thanks & Regards,
Arivu
 

Attachments

mik3

Joined Feb 4, 2008
4,843
The ALE pin requires only a pulse and not a continuous 5V signal. Use a pushbutton to pulse it once. Also, you need resistors in series with each diode to limit the current.
 

beenthere

Joined Apr 20, 2004
15,819
The converter is intended to communicate with a microprocessor, not drive LED's directly. You need to place a 300 ohm resistor in series with each LED to keep high currents from destroying the internal circuitry.
 

Thread Starter

arivalagan13

Joined Apr 30, 2009
29
I tried the circuit with pulse(instead 0f +Vcc) to ALE...also with resistors in series with LEDs...but still I'm getting the same response...


Also,suggest me(with IC numbers) some popular 4-channel ADC with 8- to 12-bit resolution...and a single channel ADC with the same resolution..


Regards & Thanks,
Arivu
 

Thread Starter

arivalagan13

Joined Apr 30, 2009
29
when I connect the circuit all the LEDs are glowing(but across some LEDs I'm getting about 3.2V and 2.16V across some LEDs)..

Also I'm getting the same response(as I said above) with or without clock signal)..





Arivu
 
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