hd66789 Renesas Electronics Corporation., hd66789 Datasheet - Page 86

• Manufacturer Part Number: hd66789
• Description: 528-channel, One-chip Driver For Amorphous Tft Panels With 262,144-color Display Ram, Power Supply Circuit, And Gate Circuit
• Manufacturer: Renesas Electronics Corporation.

HD66789
Notes to the VSYNC interface
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Rev.0.12, May 09 2003, page 86 of 156
The aforementioned example of calculation is just a result of calculation. In the actual settings, causes
for the fluctuations of internal clocks and so on should be taken into consideration. It is necessary to
make a setting for the RAM write speed with enough margins.
The aforementioned example of calculation is the value in case of writing over the entire screen.
Limiting the area for the moving picture display will create more margins for the RAM write speed.
A front porch period continues after the completion of 1 frame display and until the next input of
VSYNC.
The transition between the internal clock operation mode (DM1-0 = 00) and the VSYNC interface
mode becomes effective after displaying one frame made during instruction setting.
In the VSYNC interface mode, the partial display, vertical scroll, and interlaced drive functions are not
available.
In the VSYNC interface mode, set AM to 0 to transmit display data in the aforementioned method.
In the VSYNC interface mode, write display data to RAM in the high speed write mode (HWM = 1)
VSYNC
VSYNC
Moving picture area
(14 raster-rows)
(200 raster-rows)
(14 raster-rows)
(240 raster-rows)
(20 raster-rows)
Blanking period
(20 raster-rows)
(2 raster-rows)
(2 raster-rows)
Front porch
Back porch
Front porch
Back porch
Display
RAM write
Operation through VSYNC interface
Limiting moving picture display area
Display
operation
VSYNC
VSYNC
Raster-row
Raster-row
240
240
220
Back-porch 14H
20
Back-porch 14H
0
0
RAM write
at 3.15 MHz
4.22
4.22
RAM write at 10MHz
44240 times
RAM write
at 3.15 MHz
11.17
operation
operation
Display
Display
13.41
13.55
13.55
R-C oscillation
R-C oscillation
10%
10%
13.52
16.74
16.74
60Hz
60Hz
Display operation
Display operation
[ms]
[ms]
Preliminary