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

 

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.

 

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