Analog signal to DAC

[DTM450]

Hi
Not sure if this is the right forum but

I was curious as to what happens to an analog signal when it goes to a Digital to Analog Converter
does the converter leave the signal and is through put or what

Any and all help would be awesome

[ame]

Hi
Not sure if this is the right forum but

I was curious as to what happens to an analog signal when it goes to a Digital to Analog Converter
does the converter leave the signal and is through put or what

Any and all help would be awesome

Firstly, you need to clarify your meaning. As written, your message is confusing.

You would not connect an analog signal to a Digital to Analog Converter (DAC).

If you meant Analog to Digital Converter (ADC) then it makes more sense.

As to what happens to the signal, it depends on the circuit design. ADCs usually have a high input impedance, so not much happens to the analog signal. It could be routed to another part of the circuit and used there.

[DTM450]

Sorry about the confusion I should have said 'what happens to a analog signal when it goes through an ADC'

And yes I understand you would not connect an analog signal to an ADC but I was curious as to what would happen to the signal

So then with a digital signal going through a DAC nothing happens either

[GTR2Fan]

So then with a digital signal going through a DAC nothing happens either

It comes out as an analogue representation of the digital binary input value.

[DTM450]

*sigh* (its getting late) me and my words I meant to say what would happen if an analog signal was sent through a DAC and a digital signal through an ADC

I do understand the functions of ADCs and DACs

[GTR2Fan]

The output would be wrong in either of those situations. It won't simply be passed through in its raw state because it's not what the converter expected. Is that what you were asking?

[techpaul]

Best you describe what you mean and which way signals are flowing to which parts of a DAC or ADC, as what you are saying does not make sense.

DAC have OUTPUTs of analog signals, it is rare for analog signals to go IN a DAC, no analog signals go through a DAC or ADC.

In some cases an analog signal is connected to VREF of DAC or ADC for special functions. However these days most folks use digital or analog multipliers for those sorts of functions these days.

[DTM450]

The output would be wrong in either of those situations. It won't simply be passed through in its raw state because it's not what the converter expected. Is that what you were asking?

yes sorry if i made it harder to understand than it should have been

[DTM450]

Best you describe what you mean and which way signals are flowing to which parts of a DAC or ADC, as what you are saying does not make sense.

DAC have OUTPUTs of analog signals, it is rare for analog signals to go IN a DAC, no analog signals go through a DAC or ADC.

In some cases an analog signal is connected to VREF of DAC or ADC for special functions. However these days most folks use digital or analog multipliers for those sorts of functions these days.

yes i meant if it went into the converter

[techpaul]

Best you describe what you mean and which way signals are flowing to which parts of a DAC or ADC, as what you are saying does not make sense.

DAC have OUTPUTs of analog signals, it is rare for analog signals to go IN a DAC, no analog signals go through a DAC or ADC.

In some cases an analog signal is connected to VREF of DAC or ADC for special functions. However these days most folks use digital or analog multipliers for those sorts of functions these days.

yes i meant if it went into the converter

In which way draw a diagram, give more detail

[DTM450]

ok this is probably the only way i can explain it, what are the resulting signal outputs from these inputs

[DougieLawson]

Analog in to a DAC won't produce any meaningful output. DAC needs 8 bit data.

A square wave on an ADC should generate a sensible digital output.

[techpaul]

Putting an signal INTO a DAC does NOT get a digital output, you may well BLOW the DAC.

These devices DAC and ADC are ONE direction devices, you cannot change the direction.

Just like you would not expect connecting microphone to headphone/speaker output to chnage the output into an input to an audio device.

That is why there are the two types of devices

1. DAC to produce analog output from digital input
2. ADC to produce digital output from analog input

You cannot reverse their direction.

[ame]

ok this is probably the only way i can explain it, what are the resulting signal outputs from these inputs

Ok, well, the top one makes no sense, but you could input the analog signal into one of the bits of the DAC. As the signal passes the thresholds for logic high and low you would get a one-bit change in the output. If you chose the MSb then you'd get a large-amplitude square wave out for your sine wave in.

The lower image is equally un-useful, but your output would basically switch between 0 when the square-wave input was low, and, say 255, when the square wave input was high (assuming an 8bit converter). There may be intermediate values during the transitions between high and low states, since the transition is not instantaneous, but that's what you'd see.

[techpaul]

ok this is probably the only way i can explain it, what are the resulting signal outputs from these inputs

The top diagram makes no sense as it is back to front and shows an IN that is an OUT

[techpaul]

Here is some annotated circuit symbols for an 8 bit DAC and 8 bit ADC, I believe still available and datasheets exist for TDA8702 and TDA8703

Please explain on which pins you would connect the analog signal as an INPUT on the DAC what levels, type and frequency it would be

[DTM450]

Thanks everyone you have sated my curiosity