LM2903: lm2903 power up time

Hello Stuart,

The LM2903 is a simple device, and can start up within 100's of nS depending on the ramp of the supply voltage. This is a bipolar device with no POR and a simple bias generator.

The supply voltage needs to get above 2V before it fully wakes up, then response would be similar to the lowest propagation delay.

It should be up-and-ready after about 1-2us. Note that start-up time or minimum voltage is NOT a guaranteed parameter.

But this is not simple as there are other forces at work.

Please see section 10 of the LM339 family application note. This discusses power-up behavior:

Application Design Guidelines for LM339, LM393, TL331 Family Comparators

If specific start-up behavior is required, the TLV182x/3x/5x family has POR that ensures the output is in a specific state for a specific period after crossing minimum supply voltage.

For example, the TLV1822 will keep the output high-Z for 200us after the supply voltage crosses 2.4V, then the output will reflect the inputs.