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Messages - PJoyce

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Character LCDs / Re: Understanding the Vih specification driving a 5V character LCD with 3.3V logic
« on: December 11, 2014, 05:52:05 AM »
The part numbers in the original post ( NHD-0216PZ-FL-YBW &  NHD‐0216T2Z‐FSY‐YBW‐P) were taken from the data sheets and are believed to be complete numbers.  I am not using either yet; I need to be sure that the Vih spec will not change from batch to batch in production.

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Character LCDs / Understanding the Vih specification driving a 5V character LCD with 3.3V logic
« on: December 09, 2014, 09:43:55 AM »
I am powering a 2x16 LCD with 5V but interfacing it to a processor powered by 3.3V.  The pins on the processor are 5V tolerant so the D0-D7 lines are safe to interface the processor to the display.

My question is the Vih specification, on some data sheets (ex.  NHD-0216PZ-FL-YBW) the Vih min. specification is 2.2V so driving it with 3.3V logic should be fine.  On another (ex. NHD‐0216T2Z‐FSY‐YBW‐P) the Vih min specification is 0.7*Vdd = 3.5V so not OK.  The data sheets for both reference either the SPLC780D driver (2.2Vih min) and ST7066U (0.7*Vdd).

Is there a way to know if a particular build has the SPLC780D driver chip?  The main page for all of the 2x16 character LCDs state that the controller is the ST7066U for all of the modules, so I run the risk of bad operation with 3.3V logic?

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