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wow the PCB glows...you must be using some cool new tech to run these.
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Ahh yes I had lots of fun dealing with the transients in my design. At least for the scrypt chip I'm dealing with it was not that bad because the transients occurred at the end of each hash cycle...which for this chip was in the range of 10-20 khz, so even at a 250 kHz switch rate it was manageable and enough spacing to decouple any resonances. Im pretty sure SHA cores have hash cycles in the 100s of kHz, which would be pretty nasty for a 250 kHz buck. |
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Looking good jstefanop  Any idea on final cost per unit? Final cost is $32 plus shipping. Do you know when it will come time to pay for the rest we owe and shipping? Just curious on time frame. Not until I'm ready to ship your order out. Once I can ship it out within a day or two ill contact people in the order on the list. PCB manufacturer was swamped with year end orders and since I'm "low priority" they still haven't completed all my boards. They are promising they'll ship everything out to me on Friday, so if thats the case ill be able to start shipments by midweek next week. |
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Looking good jstefanop Any idea on final cost per unit? Final cost is $32 plus shipping. |
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Alway's love new pictures to look at  . Any idea when we will see one with the black color that was selected? I'm looking forward to seeing that color on PCB. Here ya go, just got these pics from the manufacturer! *saving space from pic Really like the black! It's going to turn out to be a nice looking miner it seems like. Not many use black which I think makes it that much cooler. I have still been playing with the prototype some and it is still working away. So hope for good things from these Yea I can't wait to get my hands on these. You guys probably didn't notice but I used 2oz copper on the production version. I was getting around a 50mv voltage drop from buck to ASIC at full power draw of around 10 amps on the 1oz prototype boards. This translated to almost half a watt of wasted power and extra heat. This will be cut in half with 2oz copper so final product will be even more power efficient! |
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Does the BM1384 have isolated ground lines on the IO? If your changing core voltage on the string won't that shift the relative ground voltages and throw off your IO dividers? Unless your just igorning it and it operates fine with IO voltage going from 1.8v +/- 200mv or so.
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i am likeing that soldermask color way better then tradition green
cant wait to see some of the numbers on the sticks when u get them up and going man
Numbers have been up for a while from the prototype sticks. Check out the main thread in the Alt mining section. |
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I've got a 1uF and a 0.1uF on VREG; VDD is tied to 12V and has a pair of 2.2uF on it. The hacked '53 has only a 0.1uF on VREG. Upping VREG bypass from 1uF to 2.2uF had zero effect. The external source is a bigger LDO also powered by 12V.
Try sticking a 10uF on VDD and see what that does. |
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Not a gorram thing. Only stuff pulling from the internal LDO are the chip's own innards. The only substantial difference between what I'm running now and the hacked '53 is the switch rate - I'm at 500K where the '53 was set more like 1MHz. I'm not sure how that could make things better, especially considering the bulk of current draw would be to gate drives and that would double when the switch rate goes up.
Tying the VREG to an external 5V source actually makes things worse. The output voltage loses any semblance of regulation or stability, such that it won't even light up at 100MHz.
Weird...well you shouldn't tie VREG to an external source, since the LDO is powered from VDD anyway (unless you don't have VDD connected to 12v). Do you have at least a 1 uF bypass cap tied to VREG, and a 4.7 uF input cap to VDD? |
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 Just thought I'd show this off a little. Right now I can't get it to work past 225MHz (99GH) because the regulator is dropping out. I know what particular symptom is causing the dropout, but I'm as of yet unable to figure out what's causing that symptom. Basically, the internal 5V LDO on the TPS53355 is sagging when it starts to push more power. The initial problem with resetting I was running into was based on this - the bootstrap was drawing too much current during switch, causing the LDO to bottom out below threshold and reset the chip. I fixed that problem enough that now it starts, and it looks like I have stable hashing at 100% which is great. But when the current ramps up from either too high voltage at a given frequency (right now, if I turn it up any farther at 225MHz) or too high frequency at a given voltage (it should run 250MHz at the current voltage setting if the buck would allow it) the VREG5 slides down below 4V and resets power, which kills my string. I am primarily vexed because the hacked '53 I was using earlier did not have this problem. Its 5V was stable all the way to 820mV 300MHz. If anyone has some fresh insight as to why an internal LDO would bottom out so badly, let me know. I'll be poking for the next couple hours and hopefully I'll figure it out and won't need advice, but there's a lot of smart people around here and it rarely hurts to ask. But for now I have a stable 100GH miner. Which is pretty cool. Basically I have an S2 board with 1/8 as many ASICs and approximately 1/3 the power draw. Not good enough yet to sell, but still pretty good. When it'll run 350MHz stable I'd call it good enough to sell, but then I'd keep tweaking until it could do 400MHz pretty reliably. That should give Novak time to finish up the controls firmware. What are you running of the internal 5v LDO, and how much current is it pulling? |
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Another update for you guys, PCBs were delayed more than I liked because of the Holidays, but manufacture finally started building my order and should be complete next week. I will hopefully finish assembling and start shipping these out by end of next week if all goes well. Here are some pics manufacture sent me of the production board with black solder mask!   |
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Alway's love new pictures to look at . Any idea when we will see one with the black color that was selected? I'm looking forward to seeing that color on PCB. Here ya go, just got these pics from the manufacturer! |
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Nice work! Thats a LOT of poly caps for just 8 chips. Are you having issues with transients? Figured a single poly cap our a couple ceramics between serial plains should be enough for that design.
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Alway's love new pictures to look at . Any idea when we will see one with the black color that was selected? I'm looking forward to seeing that color on PCB. ill post the final PCB pic as soon as I have it from manufacturer! |
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Lol I love how they have a "5000w" version from a single 120v input...  |
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Sigh...people should not post shit like this if they don't know what they are talking about.
If you are a miner DO NOT USE THIS TO "MAGICALLY" GET A 240V OUTLET. Nothing will replace a true 240v line coming from a dual pole breaker in your panel. You will still be limited by 120v current, all this does is add another 10-20% efficiency loss on your line. Sure you can run your 240v only server PSU on it, but since most of those PSUs are over 2kw you'll trip your breaker before you get anywhere close to that anyway.
For that price you can probably get a real 240v line installed anyway.
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They taped out the scrypt A4 chip. Nothing on the SHA A3. They are also still looking for investors to buy the masks for the A4, so it will be a while before anything comes out...and definitely nothing on the horizon for SHA chips. |
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I think what he means is, since the chips are chained each is at a different local ground so chip-to-chip signalling might need to be shifted; is that handled internally?
The beauty of this design is that the coms are chained as well, so chip to chip is already "auto" shifted. You can see all they have is just an external resistor divider network on the coms line. Of course the end nodes still need to be shifted, but in terms of serial chain design this is as simple as it gets. |
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