NHD-C12864WC-FSW-FBW-3V3 booster

[taf]

Hi!

I’m trying to make the NHD-C12864WC-FSW-FBW-3V3 display work and I’m having some problems with the booster. The thing is that after several trials with the 4x booster network that is suggested in the datasheet I never saw anything in the screen, however, I plugged the Vout directly with 10.5 V (typical value acording with the datasheet) and screen worked perfectly. It must be some problem with the screen or booster since the voltage value monitored in Vout when it is working with the internal voltage is about 6V. I am doing something wrong or I should give the display back?

Finally I would like to point out a mistake in the datasheet of this product, the schema depicted in page 5 has capacitors missasigned, e.g. CAP3+ is tagged as C3-.

Thanks for yout time!

[Saurabh_B]

HI, is that 6V what you're seeing at Vout?

Also what type and values of capacitors are you using?

[taf]

Hi Saurabh!

Yes, i'm seeing 6V at Vout with booster 4X.  I have checked both, polyester and ceramic 1uF capacitors. I also tested 2x and 3x booster capacitor configurations and in two cases the Vout was 6V. 

Thanks!

[Saurabh_B]

I was wondering if you could confirm the number of capacitors you have in the circuit along with the values you are using for the following commands:

Power Control Set
Electronic Volume
Booster Ratio Set
Voltage Regulator internal ratio Set

[taf]

Hi Saurabh_B:
Thank you for the reply.

We have 4 capacitors of 1uF value (4x booster circuit: Vout, Vcap3P, Vcap1P, Vcap2P), and 5 capacitors of 1uF value (for V0, V1, V2, V3 and V4).
For the 2x and 3x configuration tests, we changed the capacitors according to the datasheet.

Command values:
Power Control Set
     0x2F
Electronic Volume
     Both: 0x2F and 0x3F
Booster Ratio Set
     0x00
Voltage Regulator internal ratio Set
     0x27

[cacio]

Have similar problem so I post as reply:

just got started, we built right away a number of units with NHD-C12864LZ-FSW-FBW-3V3 wired as per datasheet, see picture attached (all 1 uF caps, power is 3.1 V)

Problem is that I get no display and VOUT is 2.59 V.

I verified both schematic and layout (also attached), and actual circuit matches, so what am I doing wrong?

Is it wired wrong way around?
do I have to send any specific commands to make it (VOUT to begin with) work?

I am using (trying to) SPI 3 wire and I see clock on pin 12 and data on pin 13 and A0 toggling fine on A3, have GND on 1 and 3V on 2. I put GND on 4 and 3V on 5, in case that matters.

I could put 12 V on VOUT if that does not break it.

Finally, am I missing information? I have Rev 54 (3/17/2015) of 13 pages spec sheet (www.newhavendisplay.com%2Fspecs%2FNHD-C12864LZ-FSW-FBW-3V3.pdf) and www.newhavendisplay.com/app_notes/ST7565R.pdf chip datasheet.

thank you for helping, will return code... developing on TI MSP430i2040

finally, I cannot read those letters to post, please guys...

cacio


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[Paul_B]

Morning Cacio,

I’m sorry to hear about the trouble you are having with NHD-C12864LZ-FSW-FBW-3V3. All displays are tested before they leave our facility, chances that it is DOA is fairly low.

I looked over your schematic and found a couple issues that need to be addressed, please see the photo attached.







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[cacio]

Hallo Paul:

thank you for your prompt advise.

I did as told and put Vcc where it belongs.

Still, no success: I see no more than 2.6 V on VOUT and nothing on the LCD.

I verified with scope that the SPI clock and data are sent, as per code attached.

What should I do now?

Is it safe to place 12 V on VOUT and then keep trying to send commands till something happens?

I have been rotating some 5 units we had built, all behave the same, meaning, display does nothing except back-lights get on

Thank you again for your time and patience

Marco





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