LM339A - Test conditions for response time

Takushi-san,

If the VIO (input offset voltage) on a device was +1mV (for example) then a 5mV overdrive means that input voltage differential applied is +6mV and -4mV for high and low response time testing.

The majority of the time delay is internal so load doesn't change that propagation time. The rise time will be improved because it is set by RL and CL alone. Fall time will not change significantly.

Hi Ronald-san,

Thanks for the information. Please let me confirm the relation to the input voltage.

Do you mean that if you have 5mV overdrive to 100mV input step, the input peak to peak voltage would be 110mV , such as below ?

Best Regards,
Takushi Kawai

Takushi-san,

The peak to peak voltage is 105mV.

VIO-100mV to VIO+5mV = 105mVp-p
VIO+100mV to VIO-5mV = 105mVp-p

The 100mV was chosen because this is the amount of input needed to fully saturate the input stage.
This is also why a 5mV input is slower than a much higher input. 

Hi Ron-san,

The following is my recognition. Could you confirm if  it is correct ?

I believe "VIO" in your answer is not the parameter in the datasheet.
I think the figure in the left side is the condition of response time for 0 to 1 transition and right side is for 1 to 0 condition.

Best Regards,
Kawai

Hi Ron-san,

Thanks for your support.

Best Regards,

Takushi Kawai