5V tolerant inputs

pasini · Joined: 12 Dec 2005 Posts: 50 Location: Curitiba - Brazil

Hi all,
I am using PIC18F87J50 at 3.3V
When you say that digital pins are 5V tolerant are UART/I2C/SPI pins included ?
If so, I can connect MCU at 3.6V to a I2C peripheral working at 5V, correct ? Do I need anything else to make them work together ?
Thanks in advance,
Pasini

Ttelmah · Guest

Hint:
'We', are a user group. 'We' do not say anything about the abilities of the pins on the 18F87J50... Smile

Now, read the data sheet. Look at section 28.3
Now, remember this tolerance, _only_ applies to _inputs_. However for I2C, then look at section 10.1.4 'open drain outputs', and the example shown. Look also at table 10-1, for what pins the tolerances apply on. Note that 5.5v tolerance is present on the inputs used for the SSP, and the UART.

So, I2C connection is fine.

However use of SPI and UART connection, will depend on what input voltage levels the other device requires. The 87J, will handle the higher voltages on _it's_ inputs, but wll only drive it's outputs up to typically 2.4v. Is this high enough for the inputs of the other device?. You need to look at the data sheet for the other device.

Best Wishes