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.

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).

Manor_Villages said:

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

Click to expand...

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.

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.

thanks pple!.. Appreciate the help..