SN74LV123A: Necessity of Power-up ramp rate

Hiromu Susami

Prodigy 650 points

Part Number: SN74LV123A

Tool/software:

Hi experts,

SN74LV123A Datasheet 7.3 recommended Operating Conditions shows Δt/ΔV Power-up ramp rate(min) = 1 [ms/V]

Q1. Just to confirm, it means we should take moer than 2ms when power up the SN74LV123A right?

Q2. Other genelal purpose Logic IC does't seem to specify Power-up ramp rate. Why SN74LV123A specify this ramp rate?
　In my opinion, I wonder if this is due to the fact that it requires state retation or regulation by an external RC.

Regards,

Hiromu

9 months ago

+1 Clemens Ladisch 9 months ago

Guru 316940 points

1. Yes (this depends on the final supply voltage). Please note that due to all the decoupling capacitors, it is likely that your rate is indeed slower than that.

2. The '123 has both digital inputs (the triggers) and analog inputs (the capacitors' voltages). A very fast supply ramp rate might result in improper initialization.