30 Mar
2017
30 Mar
'17
10:14 p.m.
On 03/30/2017 09:07 PM, Tony Duell via cctalk wrote:
The fundamental rule is 'You can't change the
voltage across a
capacitor instantly'. There is a related one 'You can't change the
current through an inductor instantly'. It (of course) doesn't matter
if said capacitor or inductor is an actual component or 'strays'.
Funny that driving DRAMs would be mentioned today. Yesterday, I was
going through some of my old tubes of ICs and ran across some AM2966
DIPs. I didn't remember why I'd gotten them or even what they were.
A glance at a datasheet refreshed my memory--basically they're LS244
octal drivers intended for MOS memory address lines. They feature 25
ohm resistors in the collectors of both of the totem-pole output
transistors. Each output is spec-ed to sink a minimum of 50 ma.
It takes some muscle to drive a capacitive load.
--Chuck