NHD‐2.8‐25664UCB2 wiring
I've had a bit of trouble getting the NHD‐2.8‐25664UCB2 working. In the process I noticed something strange.
On the PCB, it seems that the VCC supplied (nominally 3V), is connected to pin 25 of the display connector, which is VDD. Table 12-1 of the display datasheet http://www.newhavendisplay.com/app_notes/SSD1322.pdf says the maximum voltage on that pin should be 2.6V. It also indicates pins 24 and 26 should be connected to a voltage which can be up to 3.5V, whereas they are only wired to capacitors on the PCB, not the input VCC.
Figure 8-16 of the datasheet shows VDDIO and VCC both connected to 3.3V and VDD left unconnected as the internal regulator is being used, essentially the other way round to the PCB.
I'm surprised this hasn't caused issues if I'm reading it correctly, but maybe it's ok as clearly other people have the display working!
That datasheet also suggests VLSS and VSS should be connected together, which they don't appear to be.
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Why no responce from NHD?
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For what it's worth, I've since tried wiring everything up as per the datasheet and it works ok.
I don't know why Newhaven wired it differently, or why that still works...0 -
Hi,
This is actually an issue. I burnt my module by applying 3.3 V to it, since VDD has absolute maximum rating of 2.75V.
Though it was working fine at 3.0 V (which is still higher than allowed for SSD1322 by the way).
I have rewired the power supply on the module, but it is already damaged. It is seen how it scans the display if I set a refresh rate to 1 Hz, but the brightness is probably 1/1000 of what was there before.
It is unfortunate that since this is originally reported by different people here on the forum it is still not fixed. I was considering using it in a prototype of my device but I am very unsure now of Newhaven being a liable supplier. Wiring mistakes are so obvious if you take a look on SSD1322 datasheet and compare it to the PCB.0 -
Hi elvisfox,
We apologize for the lack of response on this thread.
The observations described in this thread about this display's circuit design are valid and have been confirmed by our team.
The current schematic configuration has not been reported to cause any issues with the display’s normal functioning or has affected the failure rate of this display.
We are now working on a short term and a long term solution to address this matter.
The short term solution will be to update the display datasheet with a lower recommended input voltage that will be closer to the recommended range of the controller IC.
This solution will be implemented within a week.
The long term solution will be to redesign the display's PCB and we are starting on this project now.
Thank you very much for your feedback and we hope that the steps we're taking to address this matter will be satisfactory for all of our customers.
Best Regards,0
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