Discussion in "Project Help" started by    sakibnaz    Jul 28, 2019.
Sun Jul 28 2019, 12:10 pm
#1
Hi All.

I need to connect my MCU with an external SPI device which have Logic levels of HIGH 3V and LOW 2V. From the Device to MCU Logic shift I can convert the Voltage 3V/2V to 5V/0V respectively using LM339. But I am facing problem in the other direction conversion of 5V/0V to 3V/2V.

Can anyone advice any comparative Circuit or IC which I can use to make the LOW Output a Positive Voltage (i.e. 2V)? It will be great if there any Quad Differential Comparator available.

Thank you in advance.

Regards.


[ Edited Mon Jul 29 2019, 04:02 am ]
Mon Jul 29 2019, 02:25 am
#2
An LM339 may not be fast enough for reliable SPI operation.
Logic shifting is often done with FET transistors.
Search ebay for "Logic Level Converter" for ready made packages.





[ Edited Mon Jul 29 2019, 02:28 am ]

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