Multiple Voltage regulator in single IC

[emhawkable]

I am designing a circuit that forces me to use multiple 7805 to regulate voltage. Is their any IC that has multiple 7805 in a single IC with multiple inputs and outputs!!! Kindly HELP!!

 

[FoxyRick]

Not that I'm aware of.

Why exactly do you need multiple, regulated outputs? Do they need to be isolated from each other (so you also need isolated unregulated supplies if that's the case)?

There's probably another way around the problem.

 

[keith1200rs]

There are double & triple output switching regulators but I am not sure if there are multiple output linear ones. Have a look at maxim-ic.com and try their regulator selection guide.

Keith

 

[emhawkable]

Actually I am taking input from different sensors and feeding them into Ports of 8051 Microcontroller. Some of the input are around 12 v. so i have to regulate it into 5 v to be fed into port of 8051. lets suppose i am taking 6 inputs from 6 different sensors and all of then has voltage around 12 v!! I just want to avoid using six 7805 on my pcb board. Please help me out in this case.

 

[keith1200rs]

From what you describe you don't need a regulator. Are the signals analogue or digital? You need a level converter but how you do it depends on the signal levels and whether they are analogue or digital.

Keith

 

[FoxyRick]

That's not what a regulator is used for. Regulators are used for supplying power, not for dropping signal levels to an input.

If the signals you need to read are simply 12V DC, relatively low impedance, and can share the same ground as the 8051 circuit, then all you need is to use are resistor dividers to drop the voltage. At 12V, I guess that the signals meet these requirements, but you can tell us exactly what they are if you want more help.

Anyway, do something like this:



The top resistor is 4.7KΩ, the bottom one is 6.8KΩ. They will drop the voltage in the ratio 4.7/(4.7+6.8)

That will drop the 12V down to about 5V

Edit: Wow - did it really take me that long to do a quick diagram and post? lol!

 

[emhawkable]

well the signals that will be given to my 8051 from outside will be from different sensors that will be running on a car battery. I am working on interactive dash board for car usin microcontroller. The voltage will be pretty much around 12 volt. Well a simple potential driver will do it . I dont knw why was i thinking so complexx! When it could be done with a simple potential divider. Thanks FoxyRick and u too Keith for helping me out .

 

[FoxyRick]

If it's in a car, remember that the voltage will be more around 14V with the engine running.

Increasing the bottom resistor to 9.1KΩ would allow for that, and should still work at 12V when alternator is not running.

 

[emhawkable]

Well yes that i am worried about that the voltage might be a varying one from the engine dynamo which i am going to use to indicate whether engine is running or not. The voltage signal from engine dynamo increases with acceleration. What do i have to do in that case?? In case of varying voltage i cant use a fix potential divider to keep giving me 5 v ??? The voltage might vary b/w 10 to 12 or 14 v.