Interfacing QE8 3.6v to a 5v PT4115 (LED driver)

[iansmusical]

Hi All,

I'm wanting to interface a QE8 TPM output pin which operates at a 3.6v supply to the DIM input pin of a PT4115 LED driver which is internally pulled to 5v. As far as I can see from the datasheet the QE8 pins are not 5v tolerant. Therefore, I presume I'd need a level converter circuit or have I missed something? The following circuit link looks typical, would this work?

http://www.google.co.uk/imgres?biw=1375&bih=701&tbm=isch&tbnid=7zPWN7a9LiqgkM:&imgrefurl=http://www....

Thank you in advance,

Ian

[pavel_sadek · Accepted solution]

HI

from general point of view - yes, you will need a level shifter for driving 5 V inputs,

however according to the datasheet of the driver - the min input high of the driver is defined as 2.5V , this will allow you to connect them together without level shifting :smileyhappy:

by the way, 5V tolerant means you can feed the pin with 5V level, however output will be allways up to power rail only

Pavel

[iansmusical]

Hi Pavel,

Thank you for your answer, much appreciated. I did wonder about the 2.5v minimum on the PT4115 but I was more worried about destroying the devices should I have tried it without asking first.

Ian