5v to 3.3v

hi, im doing my own arduino in a pcb, im using an ftdi chip ft232rl to be precise, i am going to use a 3.3v sensor, can i use both voltages from the ftdi, the 5v for the arduino and 3.3v for the sensor? or do i have to use a regulator? step down i believe? never used one before, how do they work?

You can use both. The 3V3OUT is able to provide 50mA according to the datasheet. The 5V is from the USB 5V line.

The FTDI already has a regulator so you can use that output, and Erdin is correct, it's good for 50mA.

The other thing to look at is the signal coming from this sensor, will the 3v3 output be OK for your Arduino input. What sensor is it?


Rob

If you need more than 50mA current for your sensor(s)... it's not that hard to add a SMD LM1117-3.3 to your PCB, right? Everything you need to know about the regulator is in the datasheet.

http://pdf.datasheetcatalog.com/datasheet/nationalsemiconductor/LM1117.pdf

thx for your info, it was pretty late last night when i posted this, I said a sensor but it is a nrf24l01 wireless module, ill check if 50mA is enough, i donĀ“t think so, so ill check a regulator,

is the LM1117 the same as a lm317 but smd? im already using a lm317, im asking so i can change both to smd.

I would not consider the LM1117 to be the same as an LM317... it is a Low Drop Out (LDO) regulator that comes in fixed voltages (3.3V as an example) though there does appear to be an ADJ version so it would be pin compatible with LM317. (Likely by design) You could of course use an existing LM317 and create a 3.3V fixed output with it.

ohh, i see, its just cause i searched for the lm1117 on sparkfun and they only have the adj version, where can i find the fixed one?

digikey.com mouser.com

Taydaelectronics.com also. Many options.