ECN0010 (Audio amp)

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Werner Almesberger

ECN0010 (Audio amp)

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This one also looks as if it's getting ready for closing. A few
observations, mainly just documentation problems:

- "Removing the external amplifier (U4101) as well as the amplifier
   specific components R4114, R4112, R4109, R4108, R4110, R4113, C4117,
   C4111, C4110, C4110 and C4115."

  This seems confused. Twice C4110 ? C4110 and C4111 are still around.
  I think this should be C4114, C4115, C4117.

  Also, R4115 is missing. Maybe we could also add a word of explanation
  for each of the components, e.g., R4110 and R4113 (input), R4112 and
  R4115 (feedback), R4109 and R4114 (pull-up), R4108 (supply), C4114
  and C4115 (input decoupling), C4117 (bypass).

- "The external headphone will be connected between ROUT1 and LOUT2"
  should be LOUT1, right ?

- didn't we talk about merging the 18+39 pF caps into 56 pF caps ?
  (C4120 + C4119 and C4121 + C4122)
  Might as well do this as part of ECN0010.

- The B4102 story is confusing. We might just skip the intermediate
  step, and refer directly to ECN0032.

That's all I found.

- Werner

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Rene Harder

Re: ECN0010 (Audio amp)

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Werner Almesberger wrote:

> This one also looks as if it's getting ready for closing. A few
> observations, mainly just documentation problems:
>
> - "Removing the external amplifier (U4101) as well as the amplifier
>    specific components R4114, R4112, R4109, R4108, R4110, R4113, C4117,
>    C4111, C4110, C4110 and C4115."
>
>   This seems confused. Twice C4110 ? C4110 and C4111 are still around.
>   I think this should be C4114, C4115, C4117.
>  

Yes indeed that sounds confusing and of course we need to keep the dc
blocking caps C4110 & C4111.

ECN changed, also added R4115!

>   Also, R4115 is missing. Maybe we could also add a word of explanation
>   for each of the components, e.g., R4110 and R4113 (input), R4112 and
>   R4115 (feedback), R4109 and R4114 (pull-up), R4108 (supply), C4114
>   and C4115 (input decoupling), C4117 (bypass).
>  

Do you think that is really necessary if they get removed anyway?

> - "The external headphone will be connected between ROUT1 and LOUT2"
>   should be LOUT1, right ?
>  

fixed!
> - didn't we talk about merging the 18+39 pF caps into 56 pF caps ?
>   (C4120 + C4119 and C4121 + C4122)
>   Might as well do this as part of ECN0010.
>  

This is taken care of in ECN0038.

> - The B4102 story is confusing. We might just skip the intermediate
>   step, and refer directly to ECN0032.
>  

I deleted the sentence and keep only the reference to ECN0032.


Thanks for the review,
Rene

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Werner Almesberger

Re: ECN0010 (Audio amp)

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Rene Harder wrote:
> Do you think that is really necessary if they get removed anyway?

More "nice to have" than necessary. It helps to find them in the original
schematics.

> This is taken care of in ECN0038.

Ah, right. I've changed the 39+18 = 47 to 56. I also added spaces between
numbers and units. It's actually you who keeps making those wonderful
examples with 50Ohm, etc., that remind me why this is not a waste of
space ;-)

Thanks for the changes ! I've moved ECN0010 to "Done".

- Werner

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Rene Harder

Re: ECN0010 (Audio amp)

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Werner Almesberger wrote:
> Rene Harder wrote:
>  
>> Do you think that is really necessary if they get removed anyway?
>>    
>
> More "nice to have" than necessary. It helps to find them in the original
> schematics.
>
>  

Convinced, I'll add them to ecn0010!

>> This is taken care of in ECN0038.
>>    
>
> Ah, right. I've changed the 39+18 = 47 to 56.

I picked 47 pF on purpose because we already have this value in our BOM,
and I think in this case a 47 pF cap is sufficient.

>  I also added spaces between
> numbers and units. It's actually you who keeps making those wonderful
> examples with 50Ohm, etc., that remind me why this is not a waste of
> space ;-)
>  

Yes, I never got used to making a space between value and unit but I'll
try to improve!  ;-)

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Werner Almesberger

Re: ECN0010 (Audio amp)

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Rene Harder wrote:
>> Ah, right. I've changed the 39+18 = 47 to 56.
>
> I picked 47 pF on purpose because we already have this value in our BOM,
> and I think in this case a 47 pF cap is sufficient.

Oops, sorry. Reverted my change and added an explanation.

- Werner

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