Re: http://www.diyaudio.com/forums/attachment.php?s=&postid=1051929&stamp=1163038065 ... just noticing the dual adjustable linear voltage regulators (U3, U4) ... assuming U4 is for +5 VDC to power up the TPA2001 ... and U3 is power for the TAS5261 ... Yes?
Any concerns about using a +24 VDC (filtered, switching) supply to drive this board (into U3, U4) and setting U3 at some level close to +24 VDC ?? Correct??
The "user's manual" at http://focus.ti.com/lit/ug/slau193/slau193.pdf (page 4) indicates that the TI ("system power supply") regulator (equal to U4 ?) won't accept more than 20 VDC (???). (I know that this does not necessarily apply to our design ... just checking.)
Also wondering if this (our) design has such a limitation? The LM317 at U4 apparently has no problems with any voltage up to ~~= 40 VDC, but I wonder about the rest of the local components around U4 ... any problems??
Are there any voltage test points identified specifically for "on the board" diagnostics purposes, post assembly? ... I assume that around X5 and X3 (regulator outputs) would be tested for proper voltage prior to any "smoke test".
I suppose someone might start making "pre-assembly and assembly notes" or such prior to the shipment of the kits. (??) Posted on the /WiKi/ pages?
Any concerns about using a +24 VDC (filtered, switching) supply to drive this board (into U3, U4) and setting U3 at some level close to +24 VDC ?? Correct??
The "user's manual" at http://focus.ti.com/lit/ug/slau193/slau193.pdf (page 4) indicates that the TI ("system power supply") regulator (equal to U4 ?) won't accept more than 20 VDC (???). (I know that this does not necessarily apply to our design ... just checking.)
Also wondering if this (our) design has such a limitation? The LM317 at U4 apparently has no problems with any voltage up to ~~= 40 VDC, but I wonder about the rest of the local components around U4 ... any problems??
Are there any voltage test points identified specifically for "on the board" diagnostics purposes, post assembly? ... I assume that around X5 and X3 (regulator outputs) would be tested for proper voltage prior to any "smoke test".
I suppose someone might start making "pre-assembly and assembly notes" or such prior to the shipment of the kits. (??) Posted on the /WiKi/ pages?
Hi Ed.
U3 and U4 will be standard LM317 three terminal regulators. U3 will have feedback resistor values to set its output to 12V. That 12V will go to the TAS5261 and will also be used as the input voltage for U4. U4 will have feedback resistor values to set its output to 3.3V. The 3.3V is for the TPA2001D2 only. The TAS5261 has on chip 3.3V regulator that draws power from the 12V input.
The only component you'd have to worry about in terms of voltage rating is C34. I have that spec'd as a 50V part.
You will need two supply voltage for this board: unregulated 15V for U3 and U4 and a higher supply rail for the output stage (50V max). Something like a 12V 1A unregulated wallwart will work nicely for the lower supply voltage. You'll need a beefier transformer, rectifier, and caps for the output stage supply. I have supplied places to jumper in regulated 12V (X2) and 3.3V (X3) supplies if someone so desired. You can use those as very accessible test points if you'd like.
The X5 connector contains the through hole pads where you would jumper in external PWM signals if you aren't going to use the TPA2001D1.
U3 and U4 will be standard LM317 three terminal regulators. U3 will have feedback resistor values to set its output to 12V. That 12V will go to the TAS5261 and will also be used as the input voltage for U4. U4 will have feedback resistor values to set its output to 3.3V. The 3.3V is for the TPA2001D2 only. The TAS5261 has on chip 3.3V regulator that draws power from the 12V input.
The only component you'd have to worry about in terms of voltage rating is C34. I have that spec'd as a 50V part.
You will need two supply voltage for this board: unregulated 15V for U3 and U4 and a higher supply rail for the output stage (50V max). Something like a 12V 1A unregulated wallwart will work nicely for the lower supply voltage. You'll need a beefier transformer, rectifier, and caps for the output stage supply. I have supplied places to jumper in regulated 12V (X2) and 3.3V (X3) supplies if someone so desired. You can use those as very accessible test points if you'd like.
The X5 connector contains the through hole pads where you would jumper in external PWM signals if you aren't going to use the TPA2001D1.
" ... You will need two supply voltage for this board: unregulated 15V for U3 and U4 and a higher supply rail for the output stage (50V max). ..."
I had hoped to use my (surplus) Lambda "lab quality" +24 VDC supplies for all power connects (two of these in parallel = >> 5 Amp, 24 VDC [+/- 0.1%], noise floor >>= 100 dbr ... it says so right there in the manual) plus some audio quality snubbing caps.
I was hoping that by running around +24 VDC that the THD would stay below 0.1 % (over all) ...
I had hoped to use my (surplus) Lambda "lab quality" +24 VDC supplies for all power connects (two of these in parallel = >> 5 Amp, 24 VDC [+/- 0.1%], noise floor >>= 100 dbr ... it says so right there in the manual) plus some audio quality snubbing caps.
I was hoping that by running around +24 VDC that the THD would stay below 0.1 % (over all) ...
FastEddy said:
Sorry, I didn't mean to be misleading. You can certainly use 24V for all supply connections. As you said, the LM317 is limited to a maximum of 40V input to output differential. Since the output of U3 is set at 12V you can use up to 52V at the input (not recommended but you can) as long as you have adequate heatsinking. I suggest using a separate 12-15V unregulated wall wart supply so you don't have to use any heatsink at all.
24V will limit the output power to 36Wrms into 8ohms, but if it's well regulated it will be clean power. At low power levels a stiff unregulated supply should give pretty low levels of THD.
" ... 24VDC will limit the output power to 36Wrms into 8ohms, but if it's well regulated it will be clean power. ..."
Thta's what I want as eventually I would be putting 3 or 4 of these boards into a single case for 6 to 8 channels (ala the TI TAS5518 + TAS5261 eval. circuit, etc. ... only better (maybe?)).
Having 36 Watts per channel x 6 or 8 channels with (hopefully) THD <<=0.1% over all, input port to speakers, would be worthy goal, No?
Thta's what I want as eventually I would be putting 3 or 4 of these boards into a single case for 6 to 8 channels (ala the TI TAS5518 + TAS5261 eval. circuit, etc. ... only better (maybe?)).
Having 36 Watts per channel x 6 or 8 channels with (hopefully) THD <<=0.1% over all, input port to speakers, would be worthy goal, No?
I reviewed the schematic and layout one more time to make sure everything was as it should be and placed an order for 30 boards. I should have them in roughly 3 weeks. I'm not sure if the Thanksgiving holliday willl delay that or not...
The final dimensions of the PCB will be 3.96in by 2.994in. They will be 2 layer boards with 2oz copper, silk screen on both sides, and standard green solder mask.
The final dimensions of the PCB will be 3.96in by 2.994in. They will be 2 layer boards with 2oz copper, silk screen on both sides, and standard green solder mask.
GeWa said:For us European members that's 100.6mm x 76mm in normal dimensions.
You know I was actually using mm as the grid spacing while laying out the board but converted it to inches out of habit.
For fear of alienating any higher life forms reading this thread, the dimensions of the board in light years would be 1.06319642725E-17 x 8.03840935151E-18
Why yes there are! There is a hole in each corner of the PCB that will accomodate a 4-40 size screw. Screws and standoffs are included in the parts kit, in case anyone didn't check the latest BOM I posted.
The centers of the mounting holes are roughly 91.5mm apart horizontally and 67mm vertically. That's about 3 5/8in and 2 5/8in, respectively.
There are also two of the same size holes along the centerline of the chip that are spaced roughly 34mm apart. These holes can be used to attach a heatsink to the TAS5261 or to mount the board to a metal case. Sorry for the non standard spacing of the holes. I just placed them as equally far away from traces and parts as I could and those are the dimensions that it just happened to be.
The centers of the mounting holes are roughly 91.5mm apart horizontally and 67mm vertically. That's about 3 5/8in and 2 5/8in, respectively.
There are also two of the same size holes along the centerline of the chip that are spaced roughly 34mm apart. These holes can be used to attach a heatsink to the TAS5261 or to mount the board to a metal case. Sorry for the non standard spacing of the holes. I just placed them as equally far away from traces and parts as I could and those are the dimensions that it just happened to be.
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Hey Bob. I'm in the Lititz/Lancaster area. We're not terribly far from each other; a couple hours depending on traffic
I'm very anxious to see how this thing turns out as well. Hopefully I'll have the first board up and running in the next few weeks.
I was browsing your photo gallery and that's quite a collection of speakers you've got! Very nice looking specimens.
I'm very anxious to see how this thing turns out as well. Hopefully I'll have the first board up and running in the next few weeks.
I was browsing your photo gallery and that's quite a collection of speakers you've got! Very nice looking specimens.
300VA should be fine, but it wil never hurt anything (except your wallet) to use a transformer with a higher VA rating (that basically goes for all amplifiers). I have two transformers, a 250VA with 33VAC secondaries and a 300VA with 30V secondaries that I plan on trying out with the boards. I wouldn't use a transformer with secondary voltages higher than 33VAC because transformer regulation and line voltage variation could cause the rectified voltage to go above 50V which is the maximum supply voltage.
When I get the first board built I will first test the board with a 120VA ~24VDC supply to see how everything looks, then will hook it up to the larger hunk of iron and see what happens.
When I get the first board built I will first test the board with a 120VA ~24VDC supply to see how everything looks, then will hook it up to the larger hunk of iron and see what happens.
Hi Brian,
Thanks for your reply.
It seems like only one of this wallet killer should be able to feed both channels.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=122-680
Thanks for your reply.
It seems like only one of this wallet killer should be able to feed both channels.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=122-680
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