NHD-0420CW-AB3 Operating Voltage

John DeCesare

• February 12, 2021 07:27

Hi, I'd like to run this display at 3.3V.  The datasheet of the display states 2.8V or 5.5V yet the datasheet of the controller (US2066) specifies 2.4V -3.6V.  So question number 1) Can I run it at 3.3V?  And if so,  I believe I connected REGVdd (pin 3) to ground to select the low power 3.3V mode, correct? If I can do this, do I need to enable or disable the internal VDD regulator (Function Select register 0x71)?  Or do I enable it and it boosts the 3.3V to 5V.  The description of the power architecture is a little confusing!

The processor I am using is limited on pins and I think if I run in  6800 mode, I can strap the CS# low and it will still function properly as it seems like the data is latched on the falling edge of E. 

Thanks!!!!
John

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  Ted M.

  NHD Staff

  • February 12, 2021 15:35

  Hi John,
  
  It is acceptable to run the display with 3.3v for VDD on Pin 2.  In this case, Pin 3 for REGVDD needs to be low or connected to ground. This will disable the 5V I/O regulator.
  
  Function Select register 0x71 is used when VDD Pin 2 is at 5V and REGVDD Pin3 is at 5V.  This allows you to disable the 5v I/O regulator by command while in 5V mode only.
  
  CS# can be tied low and the display will still function correctly.
  
  Regards,

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  John DeCesare

  • February 15, 2021 15:35

  Thanks Ted! Most appreciated!

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