ahh nope apparently ground pin currents at 1A are 6.1mA, hmm so if thats the case and we use the external ground for the return, then the reg output will still be seeing the full 45v till the output caps charge.
haha beaten to the reply. yes I was thinking of the GND pin being used for return currents instead of simply a means to measure the reference, ie not a convoluted '2 terminal device'
head failing... except it isnt seeing the full voltage, only the difference, erase ground pin from thinking, not ground.
haha beaten to the reply. yes I was thinking of the GND pin being used for return currents instead of simply a means to measure the reference, ie not a convoluted '2 terminal device'
head failing... except it isnt seeing the full voltage, only the difference, erase ground pin from thinking, not ground.
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nope... you're still thinking about it a little backwards. Every pin on the TPS that used to be connected to GND will now be connected to some arbitrary voltage, let's call it VREF for fun. If VREF is connected to the true circuit GND (eg the GND of the unregulated supply feeding the reg) then the input to GND and output to GND voltages are exactly as they appear.
If you elevate VREF with a zener by 24V then all that the TPS sees is the differential voltage between Vin and VREF and Vout and VREF. The TPS shouldn't care what the true input and output voltages are relative to the actual circuit GND.
The sense pin should be connected directly to the load as one would usually do.
Cheers,
Owen
If you elevate VREF with a zener by 24V then all that the TPS sees is the differential voltage between Vin and VREF and Vout and VREF. The TPS shouldn't care what the true input and output voltages are relative to the actual circuit GND.
The sense pin should be connected directly to the load as one would usually do.
Cheers,
Owen
Tada!
It's the middle of the day here, and I've had a very big coffee, so I'm running at peak capacity
Go to bed!
Cheers,
Owen
haha OK I might just do that, I just need to go run the DPS600 load testing first
kidding
been staring at a wifi/blutooth ES9016 dac layout i'm working on for the last few hours too, diptrace functionality is great, but it has some idiosyncrasies that hurt my head too, especially since it runs in emulation in wine on mac.b I decided further caffeine was not productive a couple hours ago, fading
Hi
I need your advise on heatsink - I was looking at these 2, as they available in my country:
https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=75-604-71&toc=0&q=SK+49%2F200%2FSA
https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=75-604-70&toc=0&q=sk+49/150/SA
will they be ok? thermal resistance is 0,5K/W and 0,6K/W respectively
Thanks for your advice
Rolle
I need your advise on heatsink - I was looking at these 2, as they available in my country:
https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=75-604-71&toc=0&q=SK+49%2F200%2FSA
https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=75-604-70&toc=0&q=sk+49/150/SA
will they be ok? thermal resistance is 0,5K/W and 0,6K/W respectively
Thanks for your advice
Rolle
Hi qusb
Actually I was thinking something similar like you did with the nicely tapped heatsink you got from Conrad heatsink back in 2011:
http://www.diyaudio.com/forums/digi...ssic-pass-labs-d1-ess-dac-21.html#post2601219
It will be in a vented wooden enclosure in a desk - backside of the desk removed for better air circulation. I have separate heatsink for a Paul Hynes PR3 reg used for powering the buffalo dac. So no additional power supplies on the heatsink besides the board from OPC
Will I be ok or you think I should look for bigger heatsink than the one rated at 0,5K/W?
Thanks
Rolle
Actually I was thinking something similar like you did with the nicely tapped heatsink you got from Conrad heatsink back in 2011:
http://www.diyaudio.com/forums/digi...ssic-pass-labs-d1-ess-dac-21.html#post2601219
It will be in a vented wooden enclosure in a desk - backside of the desk removed for better air circulation. I have separate heatsink for a Paul Hynes PR3 reg used for powering the buffalo dac. So no additional power supplies on the heatsink besides the board from OPC
Will I be ok or you think I should look for bigger heatsink than the one rated at 0,5K/W?
Thanks
Rolle
OK well the heatsink we got, is just comfortable with it inside a case, it does run a little toasty in summer but its still OK. do you know what temp that heatsink rating is given at? heatsinks get more efficient as they get hotter believe it or not; the hotter they get, the more heat they can get rid of. so its important how theyve rated them.
the first one is basically the same dimensions as the conrad unit, but with a thinner base and the depth of the fins is not as much, so for me I would avoid that one if you are mounting in a desk, the wood wont take any heat away from the heatsink either like it does with my current chassis. the heatsinks we have are 0.36C/W for an 80C rise, which translates to ~0.45C/W for the temps i'm running them, which is only about hmm maybe 25C rise above ambient, meaning the heatsink can get up to 65-70C on our hottest days. for an air temp inside the chassis of ~50-60C
so really to be safe I would take the next size up if I were you
the first one is basically the same dimensions as the conrad unit, but with a thinner base and the depth of the fins is not as much, so for me I would avoid that one if you are mounting in a desk, the wood wont take any heat away from the heatsink either like it does with my current chassis. the heatsinks we have are 0.36C/W for an 80C rise, which translates to ~0.45C/W for the temps i'm running them, which is only about hmm maybe 25C rise above ambient, meaning the heatsink can get up to 65-70C on our hottest days. for an air temp inside the chassis of ~50-60C
so really to be safe I would take the next size up if I were you
EU Group 2 Shipping
Hi Guys
I have the boards and FET's packed and ready to ship, I've sent you all an email/PM with the details.
Hopefully all payments will come in over the weekend and I'll send them Monday.
This post is for the following - Blitz, lwif, Rolle, CeeVee, deanoUK, Emphrygian, Macfixer, Reenberg, ed linden.
Regards
Michael
Hi Guys
I have the boards and FET's packed and ready to ship, I've sent you all an email/PM with the details.
Hopefully all payments will come in over the weekend and I'll send them Monday.
This post is for the following - Blitz, lwif, Rolle, CeeVee, deanoUK, Emphrygian, Macfixer, Reenberg, ed linden.
Regards
Michael
Hi Buzz,
I PMmed Tr. M. (Michael) with the same question. If it works, fine, if not you will have to wait a few more days,
Luck, Ed.
Great news, owen. I just received two Evaluation boards from Ti which am planning to modify the digital volume control for my 300B SE, now I can use one of it for the NTD1
I dont think the eval board for the positive reg is going to ve useful for the NTD1 at all i'm afraid.
Zfoils in Da house! after giving the aus government their pound of flesh.... and a piece of my mind hehe.
ive not ever received such a small bag worth so much cash! the house was empty apart from me today, I was out the back for a while, didnt hear anyone. thought I would check the tracking when I came in, it said 'delivered'... I said WTF! I looked at the door, nothing, had brief meltdown, then checked the letterbox, there was a card there telling me that my package was waiting for me next door....
sure enough, my neighbour saw me looking bemused and called me over. He said they were delivering a package to him and said I wasnt home so asked him to take it. this is fedex global express, insured on nearly $4K and they just gave it to someone else... all good all is well, hes a trustworthy guy and besides what would he do with them? he obviously had no clue what they were worth and why would he.
not really very impressed with that.
still no sign of the package from opc, hopefully not too far away.
ive not ever received such a small bag worth so much cash! the house was empty apart from me today, I was out the back for a while, didnt hear anyone. thought I would check the tracking when I came in, it said 'delivered'... I said WTF! I looked at the door, nothing, had brief meltdown, then checked the letterbox, there was a card there telling me that my package was waiting for me next door....
sure enough, my neighbour saw me looking bemused and called me over. He said they were delivering a package to him and said I wasnt home so asked him to take it. this is fedex global express, insured on nearly $4K and they just gave it to someone else... all good all is well, hes a trustworthy guy and besides what would he do with them? he obviously had no clue what they were worth and why would he.
not really very impressed with that.
still no sign of the package from opc, hopefully not too far away.
Sorry, qusp, I don't quite understand your comment, could you explain more details? Is this not the pair of LDO that Owen mentioned?
yeah that would be cool, i've also bought some manganin to try winding some of my own for a bit of fun, but I didnt think the Isabellenhutte were rated for the dissipation we need here?
bigpandahk: the eval boards you have pictured? no, thats not the regs we are talking about. there are something like 100 ti regulators starting with tps7A. the ones we are talking about are rated for 1A, the one you have there will do 200m and 150ma max respectively.
it needs to be modified to cope with the higher voltage, as discussed and it needs a hell of a lot more copper for heatsink than on the eval board even if it could cope with the current.
we are talking about the TPS7A3301 (neg) which is QFN20 and is the matching negative counterpart to the TPS7A4700 youve been using for fifo and is on Ians reg board.
the negative part is not yet available in stock at digikey in the QFN20, will be soon, but the eval board wont cut it for either polarity for the job we have here. I will be doing a PCB shortly for them. with 2 pairs pos and neg, with additional heatsinking possibilities, higher voltage caps, the elevated voltage modification to get them to do +/-45v. I plan to make it so that it can sit under the edge of the IV board and with outputs that match the input positions.
bigpandahk: the eval boards you have pictured? no, thats not the regs we are talking about. there are something like 100 ti regulators starting with tps7A. the ones we are talking about are rated for 1A, the one you have there will do 200m and 150ma max respectively.
it needs to be modified to cope with the higher voltage, as discussed and it needs a hell of a lot more copper for heatsink than on the eval board even if it could cope with the current.
we are talking about the TPS7A3301 (neg) which is QFN20 and is the matching negative counterpart to the TPS7A4700 youve been using for fifo and is on Ians reg board.
the negative part is not yet available in stock at digikey in the QFN20, will be soon, but the eval board wont cut it for either polarity for the job we have here. I will be doing a PCB shortly for them. with 2 pairs pos and neg, with additional heatsinking possibilities, higher voltage caps, the elevated voltage modification to get them to do +/-45v. I plan to make it so that it can sit under the edge of the IV board and with outputs that match the input positions.
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