Voltage Regulation - Electronic Circuits Projects Diagrams Free

Manor_Villages · 8th December 2008, 08:57 PM

I dont have much knowledge about electronic devices but I am working on a project.

I have a bluetooth module which needs an supply voltage of 3.3 V and the minimum of 150mA supply current. I have bought a voltage regulator that has a maximum output of 800 mA and output voltage of 3.3V so that it converts the 5 V ouput from the pic board to 3.3V to drive the bluetooth module.

My question is how would i reduce the 800mA to 150 mA as it would damage the module if more current passes through it.

**Nigel Goodwin** · 8th December 2008, 09:56 PM

You don't, it will only take the current it needs - the capacity of the supply makes no difference (as long as it's big enough).

crutschow · 8th December 2008, 11:11 PM

Quote:

Originally Posted by Manor_Villages

My question is how would i reduce the 800mA to 150 mA as it would damage the module if more current passes through it.

That concern about current seems to be a common misconception about voltage regulated power supplies. A voltage regulator supply regulates the voltage, not the current. The current rating is just the maximum current it can safely deliver to a load, not the amount of current it delivers all the time (that would make it a current regulator, not a voltage regulator). As Nigel stated, if you apply the correct voltage to the module, then it will draw just the current it needs.

Hero999 · 8th December 2008, 11:48 PM

There are some sensible concerns over current rating:

On poorly regulated supplies the line voltage will be considerably higher at lower currents.
If the supply is protected by a circuit breaker, intended to protect the device or cable attached to it, a higher rated supply would offer insufficient protection.

#1 can be solved by adding a voltage regulator and #2 by adding a fuse or PTC resistor.

A classic example of: #1 is using an oversized wall plug and #2 is using a car battery to power a small radio.

Manor_Villages · 9th December 2008, 04:09 AM

thanks pple!.. Appreciate the help..

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8th December 2008, 08:57 PM	#1
Manor_Villages	Voltage Regulation I dont have much knowledge about electronic devices but I am working on a project. I have a bluetooth module which needs an supply voltage of 3.3 V and the minimum of 150mA supply current. I have bought a voltage regulator that has a maximum output of 800 mA and output voltage of 3.3V so that it converts the 5 V ouput from the pic board to 3.3V to drive the bluetooth module. My question is how would i reduce the 800mA to 150 mA as it would damage the module if more current passes through it.

8th December 2008, 09:56 PM	#2
Nigel Goodwin	You don't, it will only take the current it needs - the capacity of the supply makes no difference (as long as it's big enough). __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

8th December 2008, 11:48 PM	#4
Hero999	There are some sensible concerns over current rating: On poorly regulated supplies the line voltage will be considerably higher at lower currents. If the supply is protected by a circuit breaker, intended to protect the device or cable attached to it, a higher rated supply would offer insufficient protection. #1 can be solved by adding a voltage regulator and #2 by adding a fuse or PTC resistor. A classic example of: #1 is using an oversized wall plug and #2 is using a car battery to power a small radio. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

9th December 2008, 04:09 AM	#5
Manor_Villages	thanks pple!.. Appreciate the help..