Sample and Hold + Input Protection

[List, Chris]

On Thursday, November 13, 1997 5:08 PM, Roy Tate
[SMTP:roytate at ionet.net] wrote:
> Has anyone used a LF398 monolithic sample and hold
> in a module?  The data sheet looks very promising.
> 

Simple, good, works as advertised. It's not super fancy (ie leakage and
aquisition time specs) - compared to some of the AD or bigger package
Harris devices, but it's good. I used it when experimenting with a
voltage quantizer and had no complaints.

> On a seperate topic, what does everybody here do for input 
> protection?  To give you an idea what I am talking about,
> I was reading the "CMOS Cookbook" and saw an example
> on page 44 of interfacing an op-amp to CMOS.  The op-amp 
> was powered by +15 and -15, and the CMOS was powered 
> by some lower voltage, let's say +7.5 and -7.5.  The op-amp
> output went through a 12K resistor, and then was protected
> by 2 diodes, one to +7.5, the other to -7.5, and then to
> the CMOS gate.

Hmmm, I'm not a big fan of multiple power supplies myself, so I run my
CMOS off of either 0 -> +15v, or -15v -> 0v. Then I use the same
technique you described but with only one diode and (as Gene mentioned)
a higher resistor value (30K ->100K)...

- CList