TDA1387 stacking
In my current Ozone implementation I solder up a stack of 6 TDA1387s. All 8 pins are connected together down the stack so its a relatively simple exercise - just bend the top 5 DAC chip's pins down with tweezers and apply plenty of solder from a fine-tipped iron. Check continuity from top to bottom chip with a multimeter on all 8 pins as its easy to miss a narrow gap where the solder hasn't filled in between pins.
The TDA1387 has an internal resistor (pin 5 to pin 7) around 20k so with a stack of 6 pin7 to pin5 should read around 3.3k. This is a sanity check for me to ensure I've not inadvertently got one or more DACs 180o 'out of phase' so to speak in the stack.
The supply current (I run from 3.6V) for each chip is around 4mA so thermals are no problem, unlike stacking TDA1543s. The entire stack of TDA1387s takes about half the current of a single TDA1543 but delivers almost twice the output current swing. What's not to like?
In my current Ozone implementation I solder up a stack of 6 TDA1387s. All 8 pins are connected together down the stack so its a relatively simple exercise - just bend the top 5 DAC chip's pins down with tweezers and apply plenty of solder from a fine-tipped iron. Check continuity from top to bottom chip with a multimeter on all 8 pins as its easy to miss a narrow gap where the solder hasn't filled in between pins.
The TDA1387 has an internal resistor (pin 5 to pin 7) around 20k so with a stack of 6 pin7 to pin5 should read around 3.3k. This is a sanity check for me to ensure I've not inadvertently got one or more DACs 180o 'out of phase' so to speak in the stack.
The supply current (I run from 3.6V) for each chip is around 4mA so thermals are no problem, unlike stacking TDA1543s. The entire stack of TDA1387s takes about half the current of a single TDA1543 but delivers almost twice the output current swing. What's not to like?
It will be going up on to EasyEDA - Web-Based EDA, schematic capture, spice circuit simulation and PCB layout Online shortly, I'll post up a link when its done.
The great thing about EasyEDA is that they offer a very low cost PCB manufacturing service. You're not tied in to them like some PCB tools: you can download and take your Gerbers to anyone but their prices look hard to beat.
Check out:
EasyEDA PCB fabrication prices / capabilities EasyEDA
I haven't got the hang of how to share schematics on EasyEDA yet, so in the meantime here's a pdf of the DAC board's schematic. This takes I2S input and is designed to interface with an AD815 post amplifier, schematic for which I'll post up next. Alternative post-amps are of course possible - for example AD605 or AD603 can be used to include a DC voltage programmed volume control. AD815 has the advantage that its able to drive low impedance headphones without too much trouble via a trafo.
The board is designed to sit atop a hexacap, size determined by the end user's demands for LF definition Hence no PSU details shown on the schematic.
The board is designed to sit atop a hexacap, size determined by the end user's demands for LF definition
Hence no PSU details shown on the schematic.
Last edited:
@abraxalito,
To share a Project with anyone (i.e. make it public) in EasyEDA, basically you right-click on the Project folder that you have put your designs into, click Modify and then next to Visibility, click Public.
This allows anyone to see or clone it but not to edit your original.
Clones can be edited.
Next, open any schematic or PCB layout file in that project and click on the green Share icon (the < shape to the right of the blue gear wheel.
Then select either the url for the Active file (to share only the file you have just opened) or Active Project to share everything in the project folder. Copy and paste that into your forum post and then anyone can see it.
Anyone with the url can then open it in the Editor by clicking on the little green pencil icon in the upper right of the viewing window. Save it to Anonymous files or your own project when prompted and off you go!
It is also possible to set the Project to Public or Private but to then share it with read-only or read-write permissions with selected people (who must also have an account with EasyEDA) by right-clicking on the Project folder and then clicking on Access Control. This opens a simple dialogue box which, when completed, alerts those people to the Project being added to their Shared With Me folder. They can then decide whether to accept or reject the shared Project.
There's some help on setting up sharing in EasyEDA here:
Sharing -- EasyEDA tutorial 140224
To share a Project with anyone (i.e. make it public) in EasyEDA, basically you right-click on the Project folder that you have put your designs into, click Modify and then next to Visibility, click Public.
This allows anyone to see or clone it but not to edit your original.
Clones can be edited.
Next, open any schematic or PCB layout file in that project and click on the green Share icon (the < shape to the right of the blue gear wheel.
Then select either the url for the Active file (to share only the file you have just opened) or Active Project to share everything in the project folder. Copy and paste that into your forum post and then anyone can see it.
Anyone with the url can then open it in the Editor by clicking on the little green pencil icon in the upper right of the viewing window. Save it to Anonymous files or your own project when prompted and off you go!
It is also possible to set the Project to Public or Private but to then share it with read-only or read-write permissions with selected people (who must also have an account with EasyEDA) by right-clicking on the Project folder and then clicking on Access Control. This opens a simple dialogue box which, when completed, alerts those people to the Project being added to their Shared With Me folder. They can then decide whether to accept or reject the shared Project.
There's some help on setting up sharing in EasyEDA here:
Sharing -- EasyEDA tutorial 140224
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