ade3800 STMicroelectronics, ade3800 Datasheet - Page 29

• Manufacturer Part Number: ade3800
• Description: Analog Lcd Display Engine For Xga And Sxga Resolutions With Embedded Lvds And Rsds Transmitters
• Manufacturer: STMicroelectronics

ADE3800
4.4 Analog Dithering (ADTH)
Note:
4.4.1
4.4.2
Note:
4.4.3
4.4.4
The ADTH block generates a 3-bit dither pattern ADTH_OUT[2:0] to tune the 10-bit resolution of the
ADC block.
ADTH_OUT[2:0] is not a register but the generated 3-bit dither output of the ADTH block.
Function
The ADTH block consists of a 32x32x3 bit look up table (LUT). It represents one dither matrix, which
can be read using a programmable addressing technique as well as a programmable output
amplitude control. When ADTH_MAT_CTRL[0] is zero or during the clamp pulse ADTH_OUT[2:0] =
3. During vertical blanking ADTH_OUT[2:0] is set to ADTH_TEST_DITHER[2:0] to provide a
feedback mechanism for calibration.
Addressing Technique
The ADTH block offers a programmable addressing technique to generate various temporal dither
patterns.
displacement of the dither matrix from frame to frame (precisely at rising edge of CLAMP_IN and at
falling edge of VENAB).
After (
will be reset to zero/zero, only when
To set the frame accumulator to zero, program
ADTH_FRAME_CTRL [3:0]
horizontal and vertical dimensions using
respectively.
Output Amplitude Control
The 3-bit LUT output value can be scaled to a reduced dither amplitude using ADTH_MAT_CTRL
[5:4]. After adding the ADTH_MAT_CTRL [7:6] to the (reduced) dither amplitude the final 3-bit
amplitude is output as ADTH_OUT[2:0].
Miscellaneous
During the ADC clamp pulse, the output of the ADTH block is muted; that is the output value is set
to 3 (ADTH_OUT[2:0] = 3). In addition, ADTH_CLAMP_CTRL[7:4] delays the clamp pulse by 0 to
15 clock cycles while muting, and ADTH_CLAMP_CTRL[3:0] adds 0 to 15 clock cycles of muting
after the falling edge of the clamp pulse.
For AFE dither calibration, ADTH_OUT[2:0] can be programmed via ADTH_TEST_DITHER to a
static value during vertical blanking.
ADTH_FRAME_CTRL [3:0]
ADTH_FRAME_CTRL [7:4]
to 1.
ADTH_FRAME_CTRL [7:4]
+ 1) number of frames the horizontal/vertical displacement position
is a 4-bit increment value, which defines the horizontal/vertical
ADTH_FRAME_CTRL [3:0]
ADTH_MAT_CTRL [2]
ADTH_FRAME_CTRL [7:4]
can be independently activated in the
> 0.
and
Register Description by Block
ADTH_MAT_CTRL [3]
to zero and program
,
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