Nonideal Comparator Output Limitations

[gigaJoule]

I'm trying to analyze a circuit with an LM339A, and I've been mulling over the datasheet for hours, but nothing seems to suggest anything about the limitations of the output.

I have found that the input voltages are limited to:
-0.3 < V_in < V_supply - 1.5V
which with my +5V supply is:
-0.3 < V_in < 3.5V

But does anyone know how to think about the output of non-ideal comparators? Thank you so much in advance!

 

[crutschow]

The data sheet lists the "Output Sink Current", "Output Leakage Current", and "Saturation Voltage" which are limitations.

The Maximum Supply Voltage also applies the maximum output voltage you can generate, so thats another limitation.

Another significant consideration is the "Response Time" which determines how fast the comparator will operate.

In general, the whole data sheet is basically a listing of the limitations on the operation of any IC.

 

[gigaJoule]

Thanks, crutschow! Just had one quick follow up question on saturation voltage. Please correct me if I've written anything wrong.

Limitations In the Low State:
Output sink current - the maximum current the output of the device can sink
Saturation voltage - the lowest the output can go in the low state???? ie why people say it does not always go to perfectly down to zero volts?

Limitations In the High State:
Output leakage current - the maximum current let out of the pin.

 

[crutschow]

Thanks, crutschow! Just had one quick follow up question on saturation voltage. Please correct me if I've written anything wrong.

Limitations In the Low State:
Output sink current - the maximum current the output of the device can sink
Saturation voltage - the lowest the output can go in the low state???? ie why people say it does not always go to perfectly down to zero volts?

Limitations In the High State:
Output leakage current - the maximum current let out of the pin.

Yes the saturation voltage is the non-ideal output voltage in the low ("transistor on") state. Ideally it would be 0V. For most applications, this voltage is negligible.

The output leakage current is the current the output transistor conducts in the off state. Ideally it would be 0A. For normal circuit impedances, this current is usually negligible.