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74LV4052 Dual 4-channel analog multiplexer/demultiplexer

I currently am using a multiplexor to connected to one analog channel from my Arduino. The multiplexor is connected to 4 pressure sensors that draw approximately 100mA while in use.

Because I don't want to keep my pressure sensors powered on all the time, I want to use a NPN transistor to complete the circuit.

However I want to complete the circuit by using the same combinations of GPIO's high and low that I am using for the multiplexor.

My current design is using a demux to help me bring the proper transistors high or low. I would tie in the same GPIO's that I use for the multiplexor to keep the sensors powered on and readings acquired in sync.

I just stumbled upon a IC that is a multiplexor/demultiplexer (dual)

I am not familiar with the component, would I be able to simplify my project by using the component listed above?

I understand I need the transistors to complete the circuit because I can not achieve enough current with the demultiplexer.

I appreciate your help in advanced, please let me know if you would like further clarification.

Thanks!

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  • \$\begingroup\$ 1.**Are your pressure sensors switches or transducers? **2. Can you post a data sheet or a link to one, please? \$\endgroup\$ – EM Fields Nov 7 '16 at 1:09
  • \$\begingroup\$ I used pressure sensors as an example. My focus was more on the solution needing the transistors. \$\endgroup\$ – ADL Nov 7 '16 at 1:13
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    \$\begingroup\$ The question still remains: "Are the sensors you referred to pressure transducers or pressure switches?", and the reason I asked for the data sheet was to determine whether the sensors' outputs would be adversely affected by the pass transistor's output saturation resistance. Can/will you please either post the sensor's data sheet or a link to it? \$\endgroup\$ – EM Fields Nov 7 '16 at 1:41
  • \$\begingroup\$ Okay for example, te.com/usa-en/product-CAT-PTT0058.html \$\endgroup\$ – ADL Nov 7 '16 at 4:14
  • \$\begingroup\$ Another example would be a LED. Or for example something like the DHT22 adafruit.com/product/385. \$\endgroup\$ – ADL Nov 7 '16 at 4:21
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Yes, you could use half the chip to select the analog signal and half to control the power, provided the sensors are powered from Vcc, which must be 5V or less (5.5V abs max).

For example, use 4x P-channel MOSFETs with gate-to-source resistors and ground the common so only one is on at once.

schematic

simulate this circuit – Schematic created using CircuitLab

If your sensors require a higher voltage then the circuit will have to be somewhat more complex, but the same chip can be used.

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  • \$\begingroup\$ Everything is powered by a 3.3v regulator. \$\endgroup\$ – ADL Nov 7 '16 at 0:57
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    \$\begingroup\$ Then you're fine, but be sure to use a MOSFET that turns on fully with 3V such as the one I show above. Note that you can use the INH input to turn all the sensors off to save even more power. \$\endgroup\$ – Spehro Pefhany Nov 7 '16 at 1:26
  • \$\begingroup\$ Hi, so the 74LV4052 is no good? Or are you talking about the transistors? \$\endgroup\$ – ADL Nov 7 '16 at 2:19
  • \$\begingroup\$ The MOSFETs. The chip is just fine. \$\endgroup\$ – Spehro Pefhany Nov 7 '16 at 2:20
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    \$\begingroup\$ Consider these instead. They will drop almost nothing at 100mA, require fewer resistors and there is less worry about the variation in switch on resistance than you'd have with a BJT such as the 2N3904. \$\endgroup\$ – Spehro Pefhany Nov 7 '16 at 2:33

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