LM1236 National Semiconductor Corporation, LM1236 Datasheet - Page 17

• Manufacturer Part Number: LM1236
• Description: 150 Mhz I2c Compatible Rgb Preamplifier With Internal 254 Character Osd Rom, 512 Character Ram And 4 Dacs
• Manufacturer: National Semiconductor Corporation

Programmable Horizontal Blank
The leading edge position of the internal horizontal blank can
be programmed with respect to the horizontal flyback zero
crossing leading edge in steps of 4 OSD pixels up to a
maximum of 16 steps as shown below in Figure 12. This
start position of the horizontal blanking pulse is only pro-
grammable to occur before the horizontal flyback zero cross-
ing edge, and cannot be programmed in the opposite direc-
tion. The trailing edge of the horizontal blanking pulse is
independent of the programmable leading edge, and its
relativity to the Horizontal flyback trailing edge remains un-
FIGURE 12. Programmable Internal H. Blank
17
changed. To use this feature, Horizontal Blanking (0x843A[0]
which is enabled by default) and Programmable Horizontal
Blanking (0x843A[2]) must be enabled. The number of steps
is programmed with the bits in 0x843A[6:3]. When this fea-
ture is disabled, please refer to the H-Blank Time Delay - On
specification (+ Zero Crossing of I
blanking end) listed under the System Interface Signal Char-
acteristic section.
HFB
20075752
to 50% of output
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