TDA4887PS Datasheet, PDF (11/68 Pages) NXP Semiconductors – 160 MHz bus-controlled monitor video preamplifier

Philips Semiconductors
160 MHz bus-controlled monitor video
preamplifier
Product specification
TDA4887PS
7.9 I²C-bus control
The TDA4887PS contains an I²C-bus receiver for several
control functions:
• Contrast register with control bits BRI, FPOL, DISV and
DISO
• Brightness control with 8-bit DAC
• Contrast control with 8-bit DAC
• OSD contrast control with 4-bit DAC
• Gain control for each channel with 8-bit DAC
• Internal feedback reference and external reference
voltage control for each channel with 8-bit DAC
• Black level for AC coupling with 3-bit DAC
• Depth of pedestal blanking with 2-bit DAC.
After power-up and after internal power-on reset of the
I²C-bus, the registers are set to the following values (for
most applications these settings guarantee a black screen
after power-up):
• Control bit FPOL set to logic 1
• Control bits BRI, DISV and DISO set to logic 0
• All other alignment registers set to logic 0 (minimum
value for control registers).
After an intermediate power dip, all registers are set to
their initial values and an internal Power-on reset bit will be
set with the consequence that the device will give no
acknowledge on the data byte after being first addressed.
The Power-on reset bit will be reset if the control register
is addressed. It is recommended to then refresh all
registers by using the auto-increment function.
7.10 I²C-bus data buffer
7.10.1 BUFFERED MODE
Adjustments via the I²C-bus are synchronized with vertical
blanking pulse at CLI:
• Most significant bit (MSB) of subaddress is set to logic 1
• Only one I²C-bus transmission in buffered mode is
accepted before the start of the vertical blanking pulse;
following transmissions receive no acknowledge
• Received data is stored in one internal 8-bit buffer
• Adjustments will take effect with detection of the first
vertical blanking pulse after the end of the
acknowledged I²C-bus transmission
• Waiting for vertical blanking pulse in buffered mode can
be interrupted by Power-on reset
• Auto-increment is not possible
• Buffered mode should be used for user adjustments
such as contrast, OSD contrast and brightness when a
picture is visible on the monitor.
7.10.2 DIRECT MODE
Adjustments via the I²C-bus take effect immediately:
• Most significant bit (MSB) of subaddress is set to logic 0
• Number of I²C-bus transmissions in direct mode is
unlimited
• Adjustments take effect directly at the end of each
I²C-bus transmission
• Direct mode can be used for all adjustments but large
changes of control values may appear as visual
disturbances in the picture on the monitor
• Auto-increment is possible
• Vertical blanking pulse is not necessary.
2001 Oct 19
11