THS8083T Datasheet, PDF (33/61 Pages) Texas Instruments – Triple 8-Bit, 80 MSPS, 3.3-V Video and Graphics Digitizer With Digital PLL

3.2.16 Register Name: PLL_CTRL
Subaddress: 0F (R/W)
MSB
X
X
DISABLE_PFD SEL_ADCCLK
INV2
DIV2
INV3
LSB
DIV3
DISABLE_PFD:
Disables updating of the DTO increment (i.e., keeps DTO output frequency constant and independent of the
incoming HS frequency). This effect is similar as opening the PLL loop.
0 = PFD enabled
1 = PFD disabled (default): the DTO runs at a constant frequency, as determined by NOM_INC. This means
the output frequency returns to the nominal value and further updating of the DTO output frequency is
avoided (the PLL loop is open). This is chosen as the default mode to avoid false random frequency changes
by the DTO caused by noise on the HS input. In normal operation the microprocessor will periodically check
the SYNC_DETECT register. If sync is present/absent, then the PFD is enabled/disabled so, frequency drift
is avoided when no input signal is present. Still the panel can be driven then by data with a nominal pixel
frequency.
SEL_ADCCLK:
INV2 :
Selects the PLL clock or the clock signal on the EXT_ADCCLK pin, as the clock source for the ADC channels
0: internal clock selected (default)
1: external clock selected
DIV2:
Selects inverting or noninverting clock output on ADCCLK2 output pin
0: the output is not inverted (default) with respect to the internal ADCCLK1 clock
1: the output is inverted with respect to the internal ADCCLK1 clock
INV3:
Enables divide-by-2 function on the clock output of ADCCLK2
0: divide by 2 mechanism is disabled (default)
1: divide by 2 mechanism is enabled
Selects inverting or noninverting output on DTOCLK3, with respect to the internal DTOCLK3 clock
0: the output is not inverted (default)
1: the output is inverted
DIV3:
Enables divide-by-2 function on the clock output of DTOCLK3
0: divided by 2 mechanism is disabled (default)
1: divided by 2 mechanism is enabled
3.2.17 Register Name: HS_COUNT_0
Subaddress: 10 (R)
MSB
HS_COUNT7 HS_COUNT6 HS_COUNT5 HS_COUNT4 HS_COUNT3 HS_COUNT2
LSB
HS_COUNT1 HS_COUNT0
HS_COUNT[7..0]
HS_COUNT[11..0] holds the last horizontal sync period number (i.e., the number of pixel clock cycles
between the last two HS occurrences). The device updates the value at each active edge of HS. Internal
arbitration logic avoids potential read errors between the register contents and the asynchronous I²C bus.
This value can be read by the microcontroller to derive the line frequency of the incoming video/graphics
format.
Default: (changed during operation)
3–9