Author Topic: NHD-0108CZ-FSW-GBW-33V3 contrast voltage  (Read 2420 times)

perky

  • Newbie
  • *
  • Posts: 7
  • Karma: 0
    • View Profile
NHD-0108CZ-FSW-GBW-33V3 contrast voltage
« on: January 28, 2016, 03:48:12 PM »
Hi,
I'm trying to design a temperature compensation circuit for the 3.3V NHD-0108CZ-FSW-GBW-33V3 module to be used in a commercial product. This is a 'wide' temperature range module, so I presume I have to generate a negative VEE voltage and use your app note using an NTC resistor and PNP transistor in order to temperature compensate across the full range (-20 to +70 deg C).

What would be a good VEE voltage to use for this? Do you have any recommended compensation circuits for this 3.3V module? Your application notes all appear to be for 5V modules, and this module has a VO pin instead of VL, so I'm unsure exactly how to proceed.

Thanks,
Mark.

perky

  • Newbie
  • *
  • Posts: 7
  • Karma: 0
    • View Profile
Re: NHD-0108CZ-FSW-GBW-33V3 contrast voltage
« Reply #1 on: February 07, 2016, 04:49:37 PM »
Anyone?

Saurabh_B

  • Administrator
  • Hero Member
  • *****
  • Posts: 355
  • Karma: 10
    • View Profile
Re: NHD-0108CZ-FSW-GBW-33V3 contrast voltage
« Reply #2 on: February 11, 2016, 08:05:02 AM »
Mark,

You should not need to use a negative voltage input.
You would tie one end of the Temp comp circuit to the +3.3V, and the other end to 0V.

The V0 will be the same pin as VL.
« Last Edit: February 11, 2016, 08:49:40 AM by Saurabh_B »

perky

  • Newbie
  • *
  • Posts: 7
  • Karma: 0
    • View Profile
Re: NHD-0108CZ-FSW-GBW-33V3 contrast voltage
« Reply #3 on: February 12, 2016, 04:01:29 PM »
Thanks, but I'm a little confused as there is a base-emitter diode drop between VO and VEE of the PNP transistor (about 0.65V) in the temperature compensation circuits. Also VDD-VO is specified as 3.3V typical (no minimum or maximum given), presumably typical is at typical temperature and VDD voltage, so VO would be typically 0V and we need at least -0.65V for VEE just for that case. Lowering the temperature to -20degC is going to require a more negative voltage than 0V on VO so this requires even more negative voltage on VEE. Or have I misunderstood something?

Mark.
« Last Edit: February 16, 2016, 09:01:11 AM by perky »

 

NHD‐C0220AA‐FSW‐FTW Contrast

Started by mhathawayBoard Character LCDs

Replies: 1
Views: 1879
Last post March 03, 2015, 11:53:43 AM
by Retheesh_M
Adjusting NHD‐C0220BiZ‐FSW‐FBW‐3V3M contrast

Started by OBergeronBoard Character LCDs

Replies: 1
Views: 1942
Last post April 25, 2016, 03:38:21 PM
by Saurabh_B
NHD‐0216HZ‐FL‐YBW‐C adjusting contrast with manufacturer disabled pin

Started by 8510LeoBoard Character LCDs

Replies: 3
Views: 2260
Last post February 27, 2016, 09:13:09 AM
by 8510Leo
Contrast supply for NHD‐24064WG‐ATFH‐VZ#

Started by Shaun_CarawayBoard Graphic LCDs

Replies: 2
Views: 3810
Last post May 19, 2014, 10:01:31 AM
by Shaun_Caraway
NHD‐0420CW‐AG3 Contrast question

Started by RichardRBoard OLEDs

Replies: 2
Views: 2143
Last post January 16, 2016, 09:52:02 AM
by RichardR