Bob Pease on the New LM4562

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#302
Ryssen said:
OT😎 Ordered some samples of LME49740MA from National,and they want 64$ shipping and handling....:xeye: Anyone else payd shipping for samples?
Click to expand...

I ordered some LM4562 and LME49740 samples last week. Free for me.

A friend do the same and tried 3 times. Each times, he got a different shipping cost ($15, 27$ and 10$) for the same samples and quantities. He never had a choice without shipping cost.

I tried myself again with a new account created just for the test. The first time, Samples was available at no charge. Second time, the system answered "your Samples quota is over". I tried a third time and the sample was available at no charge again.

My friend and me used "pro" email and company name.

I really do not understand their way!!!

.
 
#303
shipping and handling?

Yes, I did. Shipping, handling, local taxes and customs fee.
A little under EUR 50 in total. First sample request. I considered it
not unreasonable.

Second sample request went better, after I informed them of a
recent order for a batch of duals.
 
#304
Fenris said:



Mike, the NI one filters because it's a series circuit to ground. ( http://en.wikipedia.org/wiki/RC_circuit ). The Inverted is not referenced to ground and would be classified as a modified integrator. There are more potential issues with phase and interaction with the inv topology, and usually there's no reason you need gain of less than 1.
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Could you expound on what in the inverting topology make them have more potential issues with phase interactions?

btw. A low pass filter requires a gain <1.

Mike
 
#305
Hi Folk!

I've may be a "compatibility" problem using a LM4562 in a circuit designed for an OPA2134. It's at DAC output (AK4393), the next circuit in the chain is an CS3310.

The sound is very detailed but metallic and flat. If I replace it with an AD8620 or an OP627, the sound is ok. PSU is 12,5v. I don't have the schematic yet. I've to trace it.

After, the CS3310, I have another op-amp. If I replace the original OPA3134 with an LM4562, I don't have the same symptom. All seems fine (more detail, better bass, good sound).

Any idea ?
 

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#306
stef1777 said:


I ordered some LM4562 and LME49740 samples last week. Free for me.

A friend do the same and tried 3 times. Each times, he got a different shipping cost ($15, 27$ and 10$) for the same samples and quantities. He never had a choice without shipping cost.

I tried myself again with a new account created just for the test. The first time, Samples was available at no charge. Second time, the system answered "your Samples quota is over". I tried a third time and the sample was available at no charge again.

My friend and me used "pro" email and company name.

I really do not understand their way!!!

.
Click to expand...

I had to pay $17 for 2 chips, also after the 2nd try. I still haven't tried them

:bawling: :bawling:
 
#310
So what are the bypassing requirements of this opamp? In typical National style the datasheet makes no mention of this. There is one example of a phono preamp in the datasheet with 47uF bypassing but thats all! No technical discussion of this important topic at all in the datasheet!
 
#314
I remember an article in Analog Dialogue, in which the author shows, that an ac-amplifier draws a sinusoidal current out of the +/- supply.
I have never heard of that before.
Therefore it would be wise and perhaps sufficient to connect a blocking cap between the +/- rails.
regards
 
#316
I just searched at analog.com. Sorry, I can't find the article. 😱
Maybe one of the others has a link or could explain it better.
When the amplifier drives a sinewave into a load, there is a current flowing from V+ to V-.
A decoupling cap between V+ and V- could help.
regards
 
#317
juergenk said:
I just searched at analog.com. Sorry, I can't find the article. 😱
Maybe one of the others has a link or could explain it better.
When the amplifier drives a sinewave into a load, there is a current flowing from V+ to V-.
A decoupling cap between V+ and V- could help.
regards
Click to expand...


Maybe not the paper you were looking for, but this one gives the general answer about where to put the decoupling cap(s). It depends on the internal design of the opamp, especially on where the integrator is referenced.

http://www.analog.com/UploadedFiles/Application_Notes/135208865AN-202.pdf
 
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