Analog Multiplexer-Demultiplexer Switch Vs Input Voltage - Page 1
Forum section: electronics / beginners

author: 2X
author_rank: Frequent Contributor
timestamp: April 25, 2024, 09:55:07 pm
content: Hello,I saw at the datasheet of the 74HCT4052 Multiplexer-Demultiplexer two parameters that seems similar to me but have different values. The parameters are the VI (input voltage) and the VSW (switch voltage). Why the range of the VI voltage isn't between VCC-VEE like VSW voltage? As I understand this analog Multiplexer can have on his selected input a signal/voltage between VCC-VEE and if the output will enabled the input will pass on the output (little smaller because of the RdsON of the switch) or am I wrong?Page 6https://assets.nexperia.com/documents/data-sheet/74HC_HCT4052.pdf

author: tggzzz
author_rank: Super Contributor
timestamp: April 25, 2024, 11:02:45 pm
content: That nexperia datasheet is poor: the PSU pins are inconsistenly labelled. TI's datasheet is at least consistent.I suspect you are missing the key point: there are logic level translators inside the device.The logic select controls are defined by Vih and vary with different Vcc voltage.The analogue inputs can be between Vcc and Vee. Possible values are Vcc=+5V and Vee=-5V, but others within the limits stated are possible, e.g. Vee=0V

author: thm_w
author_rank: Super Contributor
timestamp: April 26, 2024, 12:10:54 am
content: To clarify point above, that test circuit does not match the specs you are referring to, which is causing the confusion.VI is not Vis on the diagram as you've drawn.VI is from GND to Sn pin.QuoteVis range = Vos range = Vee to Vcc.

author: 2X
author_rank: Frequent Contributor
timestamp: April 26, 2024, 07:49:14 pm
content: Vis range could be the same thing with the Vsw range?Also, as I know the logic level conversion is when a chip takes for instance a CMOS voltage 12V and converted into a TTL voltage 5V or vice versa. At this chip whatever voltage will be applied between the range of Vcc-Vee will go out the same theoretically (practically little smaller because of the RDSon of the switch), so what have about to do the logic level conversion block inside the chip?

author: BrianHG
author_rank: Super Contributor
timestamp: April 26, 2024, 07:53:10 pm
content: Please read TI's or On Semiconductor's datasheet.

author: BrianHG
author_rank: Super Contributor
timestamp: April 26, 2024, 08:28:48 pm
content: https://www.ti.com/lit/gpn/cd74hc4052https://www.onsemi.com/pdf/datasheet/mc74hc4051a-d.pdf

author: 2X
author_rank: Frequent Contributor
timestamp: April 27, 2024, 09:56:23 am
content: For my opinion the ON Semiconductor’s datasheet is the most detailed. It clearly writes at the first table on the page 4 that Vis is the analog input voltage of the switches and the Vin voltage it corresponds to digital voltage (in respect to GND) and more precisely to control pins.At page 10 the datasheet describes with an example the functionality of the chip. As I understand the logic level converter is referred in the function that with a positive digital signal (e.g. 0-5V) can controlled a Vp-p analog signal (e.g. +5 - -5V; with negative values). The logic level converter takes as input a digital positive signal and then creates on his output a proper signal in order to drive the gates of the mosfets/switches that are between each analog input/output.Also, a very good detailed datasheet where is similar to 4052 is the 14052 datasheet.P.S. If anyone understand the reason that at Nexperia's datasheet referred the term Vsw (or the Vsw is the same thing with Vis in essence?) and if there is any practical purpose of it... please tell it.Thanks all of you for your replies and the help.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2024, 10:17:43 am
content: Quote from: 2X on April 27, 2024, 09:56:23 amSloppyness is a sufficient explanation. The Nexperia datasheet also uses Vcc and Vdd interchangeably. That's sufficient for me to avoid Nexperia where possible.The onsemi datasheet is better than the TI datasheet which is in turn better than the Nexperia datasheet.Onsemi is American; was Motorola.Nexperia is Chinese; was Philips.TI is American, and always was TI.