Those old tiny LCDs

I have a pair of tiny (maybe 1” diameter) LCDs and backlights I bought years ago and forgot about.

The LCD has MCLO712A03 on the flat cable. Googling that turned up a huge and largely irrelevant site for the Cybermaxx virtual reality helmet hacking from the late 90s. I gleaned what I could from there and reproduced it here.

Connectors

Molex makes a suitable connector for the LCD. Its base number is 52745 and they have various options for finish, mounting, etc. Molex also makes a suitable connector for the backlight connector, which is 51021-0300.

LCD Datasheet

I can’t get the datasheet itself, but they supplied the relevant data which I’ve duplicated here.

Pinout

Pin Symbol Description
1 VDDV V-driver supply voltage
2 VSSV V-driver supply voltage
3 VCOM Common voltage
4 Go Video signal (G)
5 Bo Video signal (B)
6 Ro Video signal (R)
7 VSSH H-driver supply voltage
8 VDDH H-driver supply voltage
9 HDATA H-shift regis. data pulse
10 /HCP4 H-shift regis. clock
11 HCP4 H-shift regis.clock
12 /HCP3 H-shift regis. clock
13 HCP3 H-shift regis. clock
14 /HCP2 H-shift regis. clock
15 HCP2 H-shift regis. clock
16 /HCP1 H-shift regis. clock
17 HCP1 H-shift regis. clock
18 VDATA V-shift regis. data pulse
19 /VCP V-shift regis. clock
20 VCP V-shift regis. clock

Timing Parameters

Input Signal (HDATA, HCPN (N=1-4), VDATA, VCP, VCP)

Parameter Symbol Min. Typ. Max. Unit
1 HCPN, /HCPN rise time tr1 50 ns
2 HCPN, /HCPN decay time tf1 50 ns
3 HCPN, HCPN + 1 phase difference td1 -50 50 ns
4 HDATA rise time tr2 50 ns
5 HDATA decay time tf2 50 ns
6 HCP1 / H CP1 (to and from ) HDATA delay td2 -50 50 ns
7 VCP, /VCP rise time tr3 50 ns
8 VCP, /VCP decay time tf3 -50 50 ns
9 VCP, /VCP phase difference td3 -50 50 ns
10 VDATA rise time tr4 50 ns
11 VDATA decay time tr4 50 ns
12 VCP, /VCP (to and from ) VDATA delay td4 -50 50 ns

Absolute Maximum Ratings

Parameter Symbol Min. Max. Unit
H-driver supply voltage VDDH-VSSH -1.0 20.0 V
V-driver supply voltage VDDV-VSSV -1.0 20.0 V
H/V driver ground-voltage difference VSSV-VSSH -3.0 2.0 V
H-driver input voltage VIH-VSSH -1.0 20.0 V
V-driver input voltage VIV-VSSV -1.0 20.0 V
Operation temperature TOPR -10 50 degrees C
Storage temperature Tstg -30 70 degrees C

Operation Ratings

Parameter Symbol Min. Typ. Max. Unit
H-driver supply voltage VDDH-VSSH 17.5 18.0 18.5 V
V-driver supply voltage VDDV-VSSV 17.5 18.0 18.5 V
H-driver input low voltage VIHL VSSH VSSH + 0.4 V
H-driver input high voltage VIHH VDDH - 0.4 VDDH V
V-driver input low voltage VIVL VSSV VSSV + 0.4 V
V-driver input high voltage VIVH VDDV - 0.4 VDDV V
Video signal center voltage VOC 6.8 7.0 7.7 V
Video signal range Vo(R,G,B) VOC +/- 6.0 V
COM voltage COM VOC - 1.9 VOC - 1.7 VOC - 1.5 V

Driving the LCD

They were largely concerned with using Sharp’s parts to drive the display, and did a lot of camcorder schematic hacking and research to do it. I figure I’d just drive it directly. The original Cybermaxx design used a Matsushita MN83803A for driving the LCD and a Sharp IR3Y05Y for the analog video processing.

It appears that the LCD signals are biased at +7VDC, and that the driver must invert the video signals to maintain a net 0VDC on any of the signals. The main supply voltage (VDD) for the LCD is 18V. The COM voltage must be between -1.5 and -1.9V from the center voltage of 7V, so it is typically 5.3V.

The PDF for the driver is attached here, and an image of the internals of the driver chip is shown here:

I’ve also archived http://home.gwi.net/~pstewart/lcdneeds.html as lcdrpoject.zip. Not much else is useful from that site.

PVD7054C.JPG (128 KB) Andrew Kohlsmith, 10/25/2012 11:19 AM

lcdproject.zip (211 KB) Andrew Kohlsmith, 10/25/2012 11:19 AM

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