Voltage Regulation

[Manor_Villages]

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]

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]

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]

There are some sensible concerns over current rating:

1. On poorly regulated supplies the line voltage will be considerably higher at lower currents.
2. 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]

thanks pple!.. Appreciate the help..