Newhaven Display Forum

Newhaven Products => Graphic LCDs => Topic started by: andresmdn on October 14, 2014, 12:39:17 PM

Title: Backlight current limiting resistor
Post by: andresmdn on October 14, 2014, 12:39:17 PM
Are they integrated into the display? I didn't see any reference to it in the datasheet of the following display, and just wanted to be certain before completing PCB layout.

http://www.digikey.com/product-detail/en/NHD-C0216CZ-FSW-FBW-3V3/NHD-C0216CZ-FSW-FBW-3V3-ND/2059234
Title: Re: Backlight current limiting resistor
Post by: Michael_L on October 16, 2014, 08:25:14 AM
No, that display is a Chip-On-Glass LCD, and contains no electronic components except for the controller IC bonded to the glass.
Title: Re: Backlight current limiting resistor
Post by: andresmdn on October 16, 2014, 10:32:16 AM
Appreciate it Michael. Any recommended values? Suppose I can grab a unit and calculate a sample forward voltage myself, but are there any standard values that work well, independent of manufacturing tolerances?
Title: Re: Backlight current limiting resistor
Post by: Michael_L on October 17, 2014, 08:18:02 AM
It really depends on how bright you want the backlight to be.  I'd say around 100Ω.
Title: Re: Backlight current limiting resistor
Post by: JB on April 27, 2015, 05:54:39 PM
Please can you confirm that being COG does not in itself imply that a display has no current limiting resistors for the backlight? I'm looking at NHD-C12864A1Z-FS(RGB)-FBW-HT1, and it appears to show some in the "Mechanical Drawing" LED circuit, but now I'm not quite sure. Thanks.
Title: Re: Backlight current limiting resistor
Post by: Paul_B on April 28, 2015, 08:20:38 AM
Hello,

NHD-C12864A1Z-FS(RGB)-FBW-HT1 is a COG display, however the glass is attached to a pcb which contains current limiting resistors, please see page 3 in the displays datasheet.

http://www.newhavendisplay.com/specs/NHD-C12864A1Z-FSRGB-FBW-HT1.pdf



Title: Re: Backlight current limiting resistor
Post by: JB on April 28, 2015, 03:54:13 PM
Thats good, thanks.