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From: John R Walliker <jrwalliker@gmail.com>
Newsgroups: sci.electronics.design
Subject: Re: Datasheet help
Date: Sun, 1 Dec 2024 16:13:20 +0000
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On 01/12/2024 15:46, Jeroen Belleman wrote:
> On 12/1/24 16:11, Cursitor Doom wrote:
>> Hi all,
>>
>> I cannot see any reference to input impedance on this datasheet. I'd have
>> thought it was a key parameter!
>>
>> https://disk.yandex.com/i/kWf8paLDWKn5rg
> 
> (The link shows the LM124/LM324 datasheet. You could have
> told us up front.)
> 
> Not really.
> 
> If it's important to you, choose one that has that spec.
> 
> Jeroen Belleman

The data sheet is from 1995, so whatever you can buy now will be
slightly different.  You do get the input bias current and input
offset current, so you can derive something useful from that.

The TI data sheet gives more information for the LM324B:

ZID Differential 10MΩ || 0.1pF
ZICM Common-mode 4GΩ || 1.5p

John