14 Oct
2012
14 Oct
'12
6:40 p.m.
I wrote:
meeting the maximum leakage current spec is quite
difficult.
Dave McGuire wrote:
Why? (if you want to go into it)
The requirements are basically:
Vol 0.7V max into 70 mA load
Vil max 1.3V
Vih min 1.7V
minimum 5 ns rise and fall times (10% to 90%)
80uA max leakage at 3.8V, 10uA max at 0V (with Vcc from 0.0V to 5.25V)
10pF max capacitance
My attempts to design anything that meets this failed on either the
leakage current, capacitive loading, or both. However, someone who is
more skilled with analog design could probably come up with something
satisfactory.
Even the National DS8641 and DS3662 didn't quite meet the requirements.
It is unclear whether the ones DEC used had been screened to better
specs (either by National or DEC).