#1829 MAX338 Analog Switch Multiplexer

all right chip of the day what's uh what's the chip of the day it is a Max uh 338 ese um got these in a grab bag at the store so had to have them uh haven't had one of these before so what is a Max 338 well it's an 8 channel low leid seos analog multiplexer now I did a video on multiplexers before and there's a whole bunch of standard multiplexers and analog switches and stuff in the DG series okay so this claims it is a direct replacement for the dg508 and 509 depending if it's a 338 or 339 so we have the 338 so we're our direct replacement for a dg508 so it's just a better part it's better specs lower leakage uh you know that all that kind of stuff so uh they're great for what does it say great for data acquisition test equipment military radios sampling holds it's got really good leakage so it sampling holds uh heads up displays all kinds of stuff right so multiplexes are used a lot I I used these uh quite a bit when I was doing um instrumentation design where I had one a to d like a big Master expensive addd and then I routed all the signals over to to Ed to the add um through through multiplexers uh 8 channel 16 channel multiplexors and stuff like that so they were very very handy um and let's see here also one of the things I was sort of proud of on one of the instruments that I did was there was a chain of processing and for troubleshooting reasons I I brought off different points in the chain and brought them to a multiplexer so I could in software interrogate each piece across the uh the chain of circuit and it could do a self test you know is the signal here yes is the signal here yes is the signal here no well then this part must be bad and then you could tell the user what was bad so yeah multiple are great they're cheap and just put sprinkle them in um so what's the claim to them of this guy uh about 220 ohms of resistance so that's another thing you need to be aware of it's not like a relay where you have almost zero ohms or you think well it's a fet and they're like really really low ohm fets 04 ohm fets or something now these are fairly High Resistance but if you're measuring voltages you don't care an extra 200 ohms doesn't doesn't matter uh so yeah so these are 220 ohms uh let's see here leakage currents 40 namps uh leakage currents yeah 40 nanoamps that's pretty small let's see here oh wait a minute oh no no no no it's much much better than that I'm sorry I'm sorry 0.005 nanoamps yeah there we go there we go at room temperature um 0.005 nanoamps yeah that's uh that's pretty small right that's five Pico amps uh yeah pretty small pretty small all right uh other thing to know um here's something to know so in order to make this video worthwhile um one of the things you should be aware of is the supply voltages on an analog switch now if an analog switch is being run from 0 to 12 volts then your signals that you're using have to be within that range right and uh usually like for this one here uh they're giving you a graph of the on Resistance versus what what the rails are what the what the voltage rails are so if you're running at at plus or minus 20 volts it's it's the best if you're operating at at plus or minus 5 volts it's not too good and in fact it changes depending on what the input voltage is and stuff so if you want to use these um switches really well use the largest Supply uh voltages that you have so in a typical circuit plus orus 15 volts would be really really good with this with this part right um plusus 5 Vols not so much right it'll work but you need to be aware of what's going on and there's a bunch of other other graphs for um different voltage conditions all right let's uh let's hook one up uh these are so 16 Parts 16 pin yeah so 16s and so I have a little uh adapter board here that I've put apart on so I can put it in my red board and uh let's hook up some power to it yeah all right I'm going to be supplying plus or minus 15 volts let's turn that on so those that's our that's our voltage rails and I'm going to be using uh a ohm meter so we're going to go directly across one of those switches and we're going to measure its ohage all right there we go so I'm look I'm reading the uh resistance across a switch that's open and this metor won't even measure it it's too high of Mega ohms that this meter won't even measure it we'll change to another meter that can measure and see what that actually is but if I turn the switch on I have a little button here I put turn switch on 185 ohms right so uh that's certainly within the within the specification and uh yeah so there you go you can measure these things directly it was such a high uh High open that we will use my keithly uh meter here and let's see what it thinks is going on I'll go across the same two pins here what does a what does the Keith Le say the Keith Le says uh 15 megga OHS yeah 15 Meg ohms is pretty good let me push the button there we go 210 uh kilohms um yeah all right a little bit different uh different measurement probably different burden voltage and stuff this is this is sourcing a particular current and the other meter sourcing a different current you're going to get slightly different readings in a in an active circuit um there you go all right so what we're going to do we're going to be using my new uh Toy which is my uh SG 503 um [Applause] sine wave generator so let's hook him up let's see here all right so I have the function generator coming in to the switch and we're going to be monitoring the input of the switch with Channel One the output with channel two and there we go so we're getting some leakage through uh the device um so it's not entirely isolated there is some uh AC coupling through the device um probably due to capacitance and stuff let's change the uh about the same so this is a 4 mahz 10 mahz 16 mahz I got about the same amount of leakage through let me turn on the switch so now the uh input and the output are the same and let's go up this is a 2 megahertz 4.7 9.6 18 megahertz oh 44 MHz it doesn't like so 18 megahertz let's go down uh there's a little bit of dip right there if you can see that the uh oops we get a little dip so there's probably some capacitance in there we get a little bit of resonance on that little capacitor in there right around the MHz I go up here's another one right around 16 MH oh and then there's a really bad one here at 23 MHz so when you use these things you have to worry about the these capacitances and inductances and stuff you'll get some resonances and um you know just be aware of that so they're not going to be perfectly flat you should characterize them they're going to be pretty flat up to you know 10 MHz or so but then uh be wary that uh it will it will kind of of uh do weirdness there let me pan down so you can see my number down number down there 23 mahz uh let's go up one 36 mahz so it can run high in frequency here uh that's completely dying at 40 yeah at uh above 40 mahz it's completely dead so yeah interesting but I'd say it's completely usable up to yeah up probably up to 20 MHz something like that all right quick uh chip of the day the max 338 so if you're using a dg508 and you want to make it better use one of [Music] these

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Keywords: s100, s-100, cpm, cp/m, cpm80, intel 8080, 8080, 8085, zilog z80, vintage computer, vintage computing, IMSAI, IMSAI 8080, ALTAIRTTL CPU, cpu design, eagle cad, eagle pcb, 8-bit CPU, 8bit CPU, diy cpu, 74181, 74381, 74382, ALUZeta, Zeta2, ROMWBW, Zeta SBCelectronic test equipment, vintage electronics, DIY electronics, electrical engineering, electronic engineering, electronics, PCB design, Circuit design

Id: bw3TWgDzX-8

Length: 10min 4sec (604 seconds)

Published: Wed Apr 10 2024