Level shifter 3,3V -> 5V

[mike81]

Hello, I need an output only level shifter from 3.3V to 5V (MCU -> IC). Is it possible to use only a pullup resistor or is an additional transistor required? I can't find any information about the protective circuit of the GPIO pins in the datasheets.

[mike81]

Thank you all very much for your support! 

I decided me for a TXB0108 bidirectional level-shifter because it's very small and no additional pull-ups are required.

Regards

Mike

[gpontis]

I suggest using a part from the 74HCT family. Power this part from the 5V supply. It will work reliably with 3.3V CMOS input. Most of these parts have a large footprint with 4, 6, or 8 gates per package, but some new parts like the 74HCT2G34 ( 2 gates ) are smaller.

[xiangjun_rong]

Hi,

As Mr George Pontis pointed out, you can use Open Collective gate such as 74HC05/74HC06 and connect the output pin of 74HC06/74HC06 to pull-up resistor, the pull-up resistor is connected to 5V, it is okay. The MK64 port pins are open drain pins, but on-chip open drain can only be pulled to 3.3V rather than 5V via external pull-up resistor.

Hope it can help you.

BR

Xiangjun Rong.

[Jorge_Gonzalez]

Hello m g:

Please specify the Kinetis part number. Some Kinetis devices have 5V tolerant pins when configured as input only, not output. But then other devices have true open drain pins. All this can be checked in the Datasheet.

So please tell us the part number and if possible the pins you want to pull-up to 5V.

Regards!

Jorge Gonzalez

[mike81]

Hello Jorge Gonzalez,

the Kinetis part number is the MK64FN1M0Vxx12. Pins are PTE3 and from PTC4 to PTC12. If I understand this correctly it is not possible to configure the MCU pins as open drain output with external 5V pull-up?

Thank you very much for your effort.

Regards

Mike

[Jorge_Gonzalez · Accepted solution]

Hi Mike:

In that case you can only pull-up to VDD, which is maximum 3.6 V. Here is an extract from datasheet:

Regards!,
Jorge Gonzalez

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