NJM567 VS LM567 - Tone Decoder Help!

Thread Starter

STUART SUTHERLAND

Joined Aug 8, 2019
1
All,

I am looking at two devices:

1. NJM567 (Made by JRC then Phillips)
2. LM567 (Made by TI)

These look fundamentally the same. The data sheet for each looks identical (same equivalent schematic). However, the formula quoted for calculating the central tone frequency differs in both data sheets (I have attached both).

1. Fo = 1 / (1.07 x R x C)
2. Fo = 1.1 / (R x C)

Before I start designing I want to understand why these are different?
I cant understand why they would be from the data sheets.

Does anyone have any experience in using either device and can fill in the blanks?
I thought equation 2 would be one I used, however I got confused when I seen the formula in data sheet 1.

Many thanks,
Stuart
 

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Alec_t

Joined Sep 17, 2013
10,355
Welcome to AAC!
There may well be slight manufacturing process differences in the two sources. But a 3% difference is hardly worth bothering about as the datasheets usually specify 'typical' device properties and give tolerance ranges.
 

ericgibbs

Joined Jan 29, 2010
8,728
hi,
I saw this difference some years ago when using Phillips 4528 monostable IC's, they used a different timing formula from other manufacturers.
E
 
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