[sdiy] Elektron Digitakt teardown

[Julian Schmidt]

ah yes, seems to be right!
something like this:
https://www.onsemi.com/pub/Collateral/TND351-D.PDF

nice idea!

Am 13.07.2017 um 15:48 schrieb rburnett at richieburnett.co.uk:
> If you're using a flyback converter you can easily put extra windings 
> on the flyback transformer to generate additional isolated voltage 
> rail outputs.  This is one of the reasons why flyback power supplies 
> are so popular.  Low cost being the other! ;-)
>
> Usually only one of the output rails from a flyback converter is used 
> for closed-loop voltage feedback.  This is often the rail with the 
> highest power loading.  The other rails have poorer regulation, but it 
> can still be pretty decent if the flyback transformer is designed 
> properly.  Maybe the LDOs are to tighten up regulation on otherwise 
> poorly regulated secondary outputs from a flyback converter.
>
> -Richie,
>
> On 2017-07-13 13:23, Julian Schmidt wrote:
>> Am 09.07.2017 um 12:42 schrieb Julian Schmidt:
>>>
>>>
>>> Am 09.07.2017 um 12:28 schrieb rsdio at audiobanshee.com:
>>>> Interesting stuff, particularly the enhanced analog isolation.
>>> yes! how does it actually work?
>>> I see two SI8660 digital isolator ICs that are probably used to 
>>> isolate the data lines for the DAC/ADC from the digital to the 
>>> analog part.
>>> +/-12V is only used for the analogue side.
>>> But how are the GNDs isolated?
>>
>> I had a closer look at the PSU.
>>
>> 12V DC input from the external wallwart go in.
>> https://www.elektron.se/wp-content/uploads/2016/11/PSU3b.jpg
>>
>> GND isolation for the digital part seems to be achieved with a LT3575,
>> an isolated 5V flyback converter.
>> http://www.linear.com/product/LT3575
>>
>> but the analog PSU is not completely clear to me.
>> They have a VPH2-0066 fixed inductor with 6 coils with 6.6uH each
>> http://www.mouser.com/ds/2/87/BUS_Elx_PM_4301_VERSA_PAC-335903.pdf
>>
>> A lot of 1117 LDO regulators to the left of the coils, but how is the
>> negative voltage generated from the +12V input?
>> I can not spot a switching regulator IC near the coils, nor a MOSFET
>> or similar to generate a PWM for a switching PSU.
>>
>> Any ideas?
>>
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