Basically looking for a Switch IC with a enable pin or something like that - Page 1
Forum section: electronics / beginners

author: Villain
author_rank: Regular Contributor
timestamp: September 28, 2016, 03:18:24 pm
content: hey guys i hope you are able to help me..I am looking for an integrated circuit which basically has 8 switches and the switches are controlled via like a enable pin.. So if i have a HIGH on that enable pin all the switches are closed, if there is a LOW on that pin all switches are open. I need 8 switches in one IC if this is possible..I searched on the internet but wasnt able to find the right one.would appreciate all help... thanks in advance(i suck at explaining this i hope youll understand)

author: tszaboo
author_rank: Super Contributor
timestamp: September 28, 2016, 03:26:34 pm
content: Is it switching analog signal, power, or digital signal?If it is analog, please also specify the voltage range of your power supply(s), and your signal.If power, please specify the voltage and maximum current.I think having 8 switches might be difficult (for analog) you need to use 2-3 chip.The search term, that can help is: "SPST", single pole single throw.

author: Villain
author_rank: Regular Contributor
timestamp: September 28, 2016, 03:32:16 pm
content: i only want to switch 3.3volts i guess other voltages arent needed atleast right now.

author: Ian.M
author_rank: Super Contributor
timestamp: September 28, 2016, 03:42:50 pm
content: So power or signal switch? The two are very different as the signal switches have a considerable ON resistance, typically of the order of 100R, and the power switches can only work correctly passing current one way.For power switches we need to know high-side or low-side.High-side: 3.3V---Switch---Load---0VLow-side: 3.3V---Load---Switch---0VFinally, is the 0V of the control circuit connected to the 0V of the load side? If not, its a whole new and far more difficult ballgame.

author: Villain
author_rank: Regular Contributor
timestamp: September 28, 2016, 03:48:06 pm
content: signal switch. on resistance shouldnt matter that much. the 0v of the control circuit are connected to the 0v of the load side.

author: Ian.M
author_rank: Super Contributor
timestamp: September 28, 2016, 04:45:19 pm
content: Difficult. TI have an 3.3V octal analog switch intended for digital applications, but with an application note on using the series for analog switching, but its control input is active low ON.See:http://www.ti.com/product/SN74CBTLV3245A/technicaldocuments(last A.N.)Otherwise, if you've got a MCU to set it up, there are a few serially controlled analog switches with a master inhibit pin that could do what you want autonomously once initialised correctly.

author: KL27x
author_rank: Super Contributor
timestamp: September 28, 2016, 11:12:37 pm
content: You mean flip flop / toggle? Or just straight pass thru?Straight pass thru, I think you want a buffer chip with an EN pin, if such a thing exists. Or just switch the power on/off (with a transistor if necessary, but it sound like simple digital logic hence any digital output pin could power it). But you would probably have to invert the logic... if the signals are default high, which is more often the case. Thus using a second inverting buffer chip if the logic must be preserved. Or maybe you could use a noninverting buffer chip and switch the ground pin.Or you could just use a transistor array with a common source pin. Switch source pin between 3.3V/ground. Signals to the gate, output to the drain with pullups to 3.3V. Open drain style. I'm using FET terminology, but the most common transistor arrays seem to be darlington pairs, for some reason. Again, you could run inputs through an inverting buffer to get the logic correct, if that is important.Flip flop, you want a .... what's the word... JK flip flop with an enable?

author: tszaboo
author_rank: Super Contributor
timestamp: September 29, 2016, 11:34:17 am
content: Two ADG811. Two ADG611. SN74CB3Q3245. SN74CBTLV3861You still did not say the real specification, so it is hard to say.

author: KL27x
author_rank: Super Contributor
timestamp: September 29, 2016, 11:49:28 am
content: I think he means just physical switches... Wild guess from how he is askingIt's been 10 years since I have sourced a buffer IC. Apparently they most all have enable pins, lol. But most of the Enable pins appear to be Low active, opposite of what you specifically asked. (Can invert a signal with a single transistor if you really need to!)Here ya go. I found 647 of them.Buffer/Line Driver IC's (knowing what it's called is 99.9% of the battle.)8 Inputs/8 OutputsSorted by pricehttp://www.mouser.com/Semiconductors/Integrated-Circuits-ICs/Logic-ICs/Buffers-Line-Drivers/_/N-6j78c?P=1yvcyi4Z1yvcyi3Z1z0sn9r&Ns=Pricing|0You might also need pullups for the input sidehttp://www.mouser.com/Passive-Components/Resistors/Resistor-Networks-Arrays/_/N-e89l?P=1yxu8a7Z1yzb07zZ1z0sqtsZ1z0wo6v&Ns=Pricing|0

author: Ian.M
author_rank: Super Contributor
timestamp: September 29, 2016, 12:11:58 pm
content: How does one get from a request for analog signalswitchesto recommending enable gated buffers or line drivers with no further input from the O.P.?

author: tszaboo
author_rank: Super Contributor
timestamp: September 29, 2016, 12:43:28 pm
content: Quote from: Ian.M on September 29, 2016, 12:11:58 pmThe 3,3V signal level is usually used for digital stuff, not analog. Analog is usually 5V, +/-12V +/-15V or something, because opamps and such work on those levels. So we assume it is digital.

author: Ian.M
author_rank: Super Contributor
timestamp: September 29, 2016, 02:04:13 pm
content: Quote from: NANDBlog on September 29, 2016, 12:43:28 pmThere's a fair few OPAMPs that will work down to 3V. e.g Dave uses a LMV321AS running from a coin cell for his uCurrent.*ASS*U*ME*ing stuff leaves both of us looking stupid if/when the O.P. gets back to this. I've already recommended a part for digital or analog switching with 3.3V Vdd, and IMHO unless one has a better 3.3VSWITCHto offer with active high enable, its best to wait for further input from the O.P.

author: KL27x
author_rank: Super Contributor
timestamp: September 29, 2016, 08:09:12 pm
content: Yeah, you are right.When he responded to AC or Digital, power or signal, et al with "only 3.3V for now" and the "switch IC or something like that" I assumed he doesn't know what is even being asked.If he knows he needs analog switch IC that can handle a whopping 3.3V and can't find it, that is the more curious thing. Switch IC's have their own categories in Mouser, et al, too...Anyhow, more options better. If he buys 5,000 and it's the wrong part.... I can assume he didn't bother reading the datasheet.I suppose since he is so specific about the enable pin logic, maybe he is trying to hack or fix something or identify a specific part? Dunno why the specifics matter so much, and sounds like he doesn't, either. I doubt we are going to hear back from him, either way.I read your reply and it is great. It's spot on if the guy already knows enough to find what he is looking for, himself. I was just betting he didn't really need a switch, and it was late. None of this makes YOU look dumb... But thanks for looking out for OP and calling out ME.Looking back at my responses, I agree it looks pretty dumb.I might have had a mini manic episode. Filter...thx.

author: langwadt
author_rank: Super Contributor
timestamp: September 29, 2016, 08:41:57 pm
content: http://xyproblem.info/

author: tszaboo
author_rank: Super Contributor
timestamp: September 30, 2016, 12:03:02 pm
content: Quote from: Ian.M on September 29, 2016, 02:04:13 pmOMG, chill out. I asked 3 questions, he answered one. Now he is either unable to answer it, in which case, ordering the buffer or the wrong chip will result an error, debugging it he will actually understand what the issue is, and learn. That is why I told him to look for SPST, or at least google the part number (more than 0 effort).Or he just doesn't care enough to answer it, in that case, I dont care if he messes it up. You know, forums are: garbage in- > garbage out.

author: Villain
author_rank: Regular Contributor
timestamp: October 02, 2016, 05:01:49 pm
content: sorry for not replying i was on vacation. i know i was really unspecific. But i was looking for a octal bus switch and because of your help i found everything i needed.thanks yall especially NANDBlog and Ianedit: i am kind of amused(?) on how the thread got so out of hand so quick..

author: tszaboo
author_rank: Super Contributor
timestamp: October 03, 2016, 10:38:57 am
content: Quote from: Villain on October 02, 2016, 05:01:49 pmDont worry, its better to have a heated argument online, than in real life. Except in the pub, about cars/women/politics/switching mode power supply topologies.

author: Ian.M
author_rank: Super Contributor
timestamp: October 03, 2016, 11:22:46 am
content: So what beers does this near-mythical pub that has patrons who argue SMPSU topologies have on tap? And where do we find it?

author: Ammar
author_rank: Regular Contributor
timestamp: October 03, 2016, 11:27:28 am
content: There are a heap of ways to solve this problem depending on the signals involved, as has been pointed out.You could have a microcontroller with at least 16 I/O pins and write a loop that reads the states on the input and sets the output...You could do the same with an FPGA/CPLD...You could connect 8 MOSFET gates together...Are you able to describe your application? It may turn out that you don't need a chip to do this at all.

author: tszaboo
author_rank: Super Contributor
timestamp: October 03, 2016, 12:02:00 pm
content: Quote from: Ian.M on October 03, 2016, 11:22:46 amIDK. I remember after university, to go to a pub called "Popcorner" (you get popcorn with your beer. it is on the corner), which was close to the university. I remember at least Staropramen (CZ) and Paulaner (DE). We were definitely discussing SMPS and/or/nand digital logic there.