convert 5V to 3.3V, how?

[sheing3003]

What should I use to reduce the 5V to 3.3V?

 

[Nigel Goodwin]

Your question makes no sense?, what's it for?, is it signal or power?, and what current is required?.

 

[sheing3003]

sorry~~
it's for power, like i have a power source which is 5V for the PIC, but my image sensor is running on 3.3V, and i dunno what's the current, it doesnt say

 

[Nigel Goodwin]

sorry~~
it's for power, like i have a power source which is 5V for the PIC, but my image sensor is running on 3.3V, and i dunno what's the current, it doesnt say

You need to find out, measure it!.

 

[Oznog]

Generally you would use a linear 3.3v regulator. In cases where higher power is involved, perhaps a switching regulator.

There are potential issues in hooking up a 3.3v device to a PIC at 5v. The PIC should be able to read 3.3v as a logical HIGH on its input. However, if the PIC provides a 5v output to the 3.3v device's input this usually causes a major problem. Can damage the device.

 

[sheing3003]

here's the typical application set up given in the datasheet
**broken link removed**
and i read through the datasheet didnt find any current limitation..
so you mean i should apply 3.3V to it and measure the current?
thanks alot for helping

 

[Nigel Goodwin]

Yes, apply power and measure it - hopefully it should be fairly low?, but bear in mind it probably needs to be working to measure it, you also have the problem of converting the I2C bus in order to setup the chip.

Have you considered running the PIC at 3.3V?, and using an LF series PIC.

 

[sheing3003]

3.3 sounds like a good idea, but will this affect my R232 communication with the PC?

 

[Nigel Goodwin]

3.3 sounds like a good idea, but will this affect my R232 communication with the PC?

Yes, but it's probably easier to do the RS232 end than the input (far less connections).

 

[DirtyLude]

Then you'll need a rs232 level shifter that supports 3.3v, like the ST3232. Which isn't hard to find.