Choose analog switch IC - Page 1
Forum section: electronics / beginners

author: Darlington
author_rank: Contributor
timestamp: April 05, 2024, 11:23:46 am
content: Hello everyone,I'm looking for an integrated circuit that allows me to switch 6 pins/inputs of an MCU with 6 others, like an SPDT configuration. I don't have high demands on the switching speed. I have no idea which IC model might be right for me.Also, I don't know if it exists, but I would like a chip that allows me to make the switch via a single command signal.Does anyone have any ideas?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: April 05, 2024, 12:19:15 pm
content: Good Morning KKK, what are the current/loads of each of those 6 'switches'

author: exe
author_rank: Unknown
timestamp: April 05, 2024, 12:21:10 pm
content: Some 4051 switch? E.g. CD4051B .

author: Victorman222
author_rank: Regular Contributor
timestamp: April 05, 2024, 12:35:00 pm
content: Well, the classic SPDT analog switch is the CD4053, that one has 3 switches in one IC so you would need to use 2 of them. Depending on your requirements that IC might not be suitable, for example it has 120 ohm closed switch resistance. To control 6 inputs with one output is harder. Something basic would be a shift register with output enable, but that needs 3 pins (data in, clock and output enable) and takes up processor time.Maybe tell us a bit more about what you are trying to do so we could help you better.

author: pcprogrammer
author_rank: Super Contributor
timestamp: April 05, 2024, 12:35:40 pm
content: Analog or digital signals?Voltage levels?You can search for "2 to 1 multiplexer" and get more useful hits than searching for switch in this case.A 74LVC157 is a quad 2 to 1 multiplexer for digital signals. Or the TS3A27518E-Q1 might be what you want. Has 6 multiplexers (switches) in one chip, but is for low voltages.

author: Zero999
author_rank: Super Contributor
timestamp: April 05, 2024, 12:36:32 pm
content: Firstly, what are you trying to do? There are various multiplexing schemes which allow multiple switches/LEDS to be read/controlled with fewer I/O pins?Secondly, this might be a silly question, but why not simply use a microcontroller with more pins?Thirdly, yes, there are a variety of analogue switches available. The 74HC4053, is an improved version of the CD4053 mentioned above. It has a much lower on resistance and lower capacitance. The only downside is a lower maximum voltage rating, but that doesn't matter, as the MCU is probably limited to 5V anyway. It contains three SPDT switches so you'll need two ICs.

author: ftg
author_rank: Frequent Contributor
timestamp: April 05, 2024, 12:49:41 pm
content: Two 74HC4053's would have been my suggestion as well.Note, 74HC4053, not 74HCT4053, as HCT if meant for 5V supply only, while HC is fine with 3V3.There are also 8 channel SPDT chips available. But 74HC4053 is simple, cheap and common.

author: Darlington
author_rank: Contributor
timestamp: April 05, 2024, 01:51:19 pm
content: First of all, thank you all for your contributions.I have to switch six tach signals with a range between 10-100Hz so I have no special requirements on the load.The signal ( sorry I forgot to write it down earlier) is a digital signal.I checked out the 74HC4053 seems that Ron is compatible with my purpose, what do you think?

author: Victorman222
author_rank: Regular Contributor
timestamp: April 07, 2024, 03:57:46 pm
content: Quote from: KKK on April 05, 2024, 01:51:19 pmFor digital signals generally multiplexers are used, so as pcprogrammer noted you can look for a 2 to 1 multiplexer. Their advantage is faster speed, as they present a high impedance input to the signal and low impedance output to the load. As for analog switch, to the signal it looks like resistor of Ron value so it will be slower (parasitic capacitance of mcu input has to get charged through the Ron resistance).For such a slow signal both will work well i suppose.

author: antercreeper
author_rank: Contributor
timestamp: April 08, 2024, 02:15:53 am
content: You can also use some relays.In fact it depends on the signal itself. The current, voltage, bandwidth, distortion....

author: aliarifat794
author_rank: Regular Contributor
timestamp: April 08, 2024, 07:28:47 am
content: You can take a look at the texas instruments analog switch ICs:https://www.ti.com/switches-multiplexers/analog/overview.html

author: Terry Bites
author_rank: Super Contributor
timestamp: April 08, 2024, 12:01:51 pm
content: For digital line selection applications, not analog I assume.Back in the day, before it was necessary to hide the pcb in your navel fluff...Tristate buffers were the norm, eg HC241s or get smarter and use an HC367 and HC368 pair.They're much cheaper than muxes and are often far easier to route on your pcb.

author: BrianHG
author_rank: Super Contributor
timestamp: April 08, 2024, 05:44:33 pm
content: Quote from: ftg on April 05, 2024, 12:49:41 pmNo, even the HC/HCT variants of the 4051/4052/4053 also support a Vee voltage down to -5v, so the analog inputs will allow a +/-5v swing, eg: a 10v IO range so long as the Vdd is at +5v.The HCTdenotes the threshold voltage at which the digital control inputs will be considered a logic High VS a logic Low.