I am looking for a way to power control (from a photon or Arduino) a large bank of (perhaps 10) individual 3.5" hard drives. These typically need 12V at 1.0@ max and +5V @ 1.5@ max each drive.
This is to implement a very large media library, in which each item is seldom accessed - so makes sense to power off drives except when accessed. In typical usage no more than two drives would be powered on at any time. Each drive attaches to an UBUNTU box via a SATA<->USB interface all attached to a USB hub. Ubuntu provides all the system software to do the auto drive mapping needed etc.
I have a partly working prototype using one of the excellent Denkovi USB controllable relay boards. BUT, those boards very briefly pulse all the relays every time the relay control register is updated: Often that causes an already running drive to drop offline (not all drives, but more than half of the motley assembly of second hand units I am using for testing). Also, as compared to - say an Infineon 16 channel high-side switch chip - the relay approach is space intensive (two relays per drive so need 20 relays or 3 Denkovi boards).
All these high-side MOS-FET switch chips come in teeny tiny SMT packages which are well beyond my eyesight capacity to solder or work with, so, I am looking for a board-level product that offers multi-channel logic controlled (pref SPI or serial) high-side power switched.
I looked at the obvious candidates such as Adafruit and so on, but didn’t find what I was looking for. Infineon themselves do a high-side power switch shield for Arduino - but it only offers three channels.
Has anyone here run across anything that might meet my needs?
What I really like about the control everything relay boards is the use of the MCP chip to control the relays as opposed to having them wired directly to the Photon/Arduino through a snubbing diode. This makes MCU reset events not effect the relay state, which in a power-sensitive circuit like hard drives, is extremely useful.
Yeah, these do look good - but at $240, a bit much for a personal project (esp as I would need 2 of them!). Also, those are solid state relays not Hi-Side power switches as such (though, yes they would work fine in my application if not for the cost!).
There should be cheaper boards around, cos - for example - the Infineon high-side controller chips I was originally looking at (e.g an ISP762T) are very low cost (~ $2 each) and, as you can see if you look at the data sheets:
they feature over current and over temp detection, protection and notification. When you get to the 8-output version (ITS4880R) you’re still only talking about $7 though admittedly at a lower power rating per channel! Still the accursed SMT though, no PDIP versions!
I wonder is there anyone out there who might be interested in developing a board around these kinds of chips (Infineon are far from the only makers, ST Micro, Linear and Mitel all seem to do similar devices). I am sure that such a board would find lots of takers in the Photon and maker community in general!
Thanks for inputs so far and for any further thoughts or steers.
@AlanSparkMan,
I fully realize and understand that our products are a bit more expensive than those manufactured by companies in Asia, which is really who we are competing with here, but if you step back for a second and realize the quality of products we are putting out, the support we offer, the warranty we stand behind our products with, and the fact that we are employing several US citizens it may help justify our product’s cost a bit. Every board we manufacture is made right here in the US(Missouri) and we also design the products here. Now I know it is not your responsibility but I would like for you to consider what it costs to produce products like this with warranty and support while employing US citizens. I can tell you for certain that you will not buy higher quality peripheral hardware for the Photon anywhere else and we stand behind that.
Another nice thing is our relay controllers have moved over to what we call the IOT footprint model. The great thing about this is you can plug in a Photon, an Electron, or (using interface adapters which we also offer) just about any other IOT platform device you can possibly imagine(including Arduino if that’s your thing).
We have a full fledged library for our 16 channel relay controllers on Particle’s community libraries as well, just search for NCD16Relay. We really couldn’t make them much easier to use with Particle We don’t use SPI. We use I2C which we personally believe is the ideal solution for these types of devices.
Anyway sorry for rambling, its just tough being a US manufacturer and hearing about how much cheaper everything else in the world is
I hope you will consider our product offerings and we look forward to serving you.
Thanks for your reply and thanks @Mjones for making the introduction. Sorry for my tardy reply - a bout of Man-flu has intervened!
I feel and understand your frustration at competing with Asian suppliers who plainly have lower overheads in every segment of their business than you have in the US and, I would imagine, because of the lower price-points they can start from, do far higher volumes than you are able to. I have frequently heard similar sentiments expressed by business people here in the UK (though in other contexts).
Sadly as this is at present a personal project from which there is no payback other than I get functionality I want to use myself, I can’t take the same stance as I would in a commercial project, much as I would wish otherwise :-). However, I will consider what you have said.
Is there any mileage in an off-forum discussion about designing a board using the multi-channel devices I mentioned earlier in the thread, to see if I can find any way to make it stack up as a commercial proposition? Those do seem to me to offer a high density and specific way to do lots of hi-side switching in a small space. But perhaps you already use devices of those sort? I will revisit your site for a closer look
That would be one way to go, but if the board failed my warranty is cooked, plus I’d have to get a new one and do the mods all over again - but I guess it may come to that!
Actually since the relay chatter time is probably no more than 100ms (to be verified!) I might put the caps (larger reservoir values) on the power outputs side on a separate board from the Denkovi board? which would get around the objections above, but it feels like it would be a multi-board wiring fest with all the possible issues that go with that… definitely a last resort!
We don’t use SPI. We use I2C which we personally believe is the ideal solution for these types of devices.